Publications by authors named "Annet M Bosch"

74 Publications

Monitoring phenylalanine concentrations in the follow-up of phenylketonuria patients: An inventory of pre-analytical and analytical variation.

JIMD Rep 2021 Mar 22;58(1):70-79. Epub 2020 Nov 22.

Translational Metabolic Laboratory, Department of Laboratory Medicine Radboud University Medical Centre Nijmegen The Netherlands.

Background: Reliable measurement of phenylalanine (Phe) is a prerequisite for adequate follow-up of phenylketonuria (PKU) patients. However, previous studies have raised concerns on the intercomparability of plasma and dried blood spot (DBS) Phe results. In this study, we made an inventory of differences in (pre-)analytical methodology used for Phe determination across Dutch laboratories, and compared DBS and plasma results.

Methods: Through an online questionnaire, we assessed (pre-)analytical Phe measurement procedures of seven Dutch metabolic laboratories. To investigate the difference between plasma and DBS Phe, participating laboratories received simultaneously collected plasma-DBS sets from 23 PKU patients. In parallel, 40 sample sets of DBS spotted from either venous blood or capillary fingerprick were analyzed.

Results: Our data show that there is no consistency on standard operating procedures for Phe measurement. The association of DBS to plasma Phe concentration exhibits substantial inter-laboratory variation, ranging from a mean difference of -15.5% to +30.6% between plasma and DBS Phe concentrations. In addition, we found a mean difference of +5.8% in Phe concentration between capillary DBS and DBS prepared from venous blood.

Conclusions: The results of our study point to substantial (pre-)analytical variation in Phe measurements, implicating that bloodspot Phe results should be interpreted with caution, especially when no correction factor is applied. To minimize variation, we advocate pre-analytical standardization and analytical harmonization of Phe measurements, including consensus on application of a correction factor to adjust DBS Phe to plasma concentrations.
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http://dx.doi.org/10.1002/jmd2.12186DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7932865PMC
March 2021

Gray and white matter are both affected in classical galactosemia: An explorative study on the association between neuroimaging and clinical outcome.

Mol Genet Metab 2020 12 6;131(4):370-379. Epub 2020 Nov 6.

Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands. Electronic address:

Background: Classical Galactosemia (CG) is an inherited disorder of galactose metabolism caused by a deficiency of the galactose-1-phosphate uridylyltransferase (GALT) enzyme resulting in neurocognitive complications. As in many Inborn Errors of Metabolism, the metabolic pathway of CG is well-defined, but the pathophysiology and high variability in clinical outcome are poorly understood. The aim of this study was to investigate structural changes of the brain of CG patients on MRI and their association with clinical outcome.

Methods: In this prospective cohort study an MRI protocol was developed to evaluate gray matter (GM) and white matter (WM) volume of the cerebrum and cerebellum, WM hyperintensity volume, WM microstructure and myelin content with the use of conventional MRI techniques, diffusion tensor imaging (DTI) and quantitative T1 mapping. The association between several neuroimaging parameters and both neurological and intellectual outcome was investigated.

Results: Twenty-one patients with CG (median age 22 years, range 8-47) and 24 controls (median age 30, range 16-52) were included. Compared to controls, the WM of CG patients was lower in volume and the microstructure of WM was impaired both in the whole brain and corticospinal tract (CST) and the lower R1 values of WM, GM and the CST were indicative of less myelin. The volume of WM lesions were comparable between patients and controls. The 9/16 patients with a poor neurological outcome (defined as the presence of a tremor and/or dystonia), demonstrated a lower WM volume, an impaired WM microstructure and lower R1 values of the WM indicative of less myelin content compared to 7/16 patients without movement disorders. In 15/21 patients with a poor intellectual outcome (defined as an IQ < 85) both GM and WM were affected with a lower cerebral and cerebellar WM and GM volume compared to 6/21 patients with an IQ ≥ 85. Both the severity of the tremor (as indicated by the Tremor Rating Scale) and IQ (as continuous measure) were associated with several neuroimaging parameters such as GM volume, WM volume, CSF volume, WM microstructure parameters and R1 values of GM and WM.

Conclusion: In this explorative study performed in patients with Classical Galactosemia, not only WM but also GM pathology was found, with more severe brain abnormalities on MRI in patients with a poor neurological and intellectual outcome. The finding that structural changes of the brain were associated with the severity of long-term complications indicates that quantitative MRI techniques could be of use to explain neurological and cognitive dysfunction as part of the disease spectrum. Based on the clinical outcome of patients, the absence of widespread WM lesions and the finding that both GM and WM are affected, CG could be primarily a GM disease with secondary damage to the WM as a result of neuronal degeneration. To investigate this further the course of GM and WM should be evaluated in longitudinal research, which could also clarify if CG is a neurodegenerative disease.
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http://dx.doi.org/10.1016/j.ymgme.2020.11.001DOI Listing
December 2020

Deep phenotyping classical galactosemia: clinical outcomes and biochemical markers.

Brain Commun 2020 29;2(1):fcaa006. Epub 2020 Jan 29.

Division of Metabolic Disorders, Department of Pediatrics, Emma Children's Hospital, Amsterdam, UMC, University of Amsterdam, Amsterdam, the Netherlands.

Early diagnosis and dietary treatment do not prevent long-term complications, which mostly affect the central nervous system in classical galactosemia patients. The clinical outcome of patients is highly variable, and there is an urgent need for prognostic biomarkers. The aim of this study was first to increase knowledge on the natural history of classical galactosemia by studying a cohort of patients with varying geno- and phenotypes and second to study the association between clinical outcomes and two possible prognostic biomarkers. In addition, the association between abnormalities on brain MRI and clinical outcomes was investigated. Classical galactosemia patients visiting the galactosemia expertise outpatient clinic of the Amsterdam University Medical Centre were evaluated according to the International Classical Galactosemia guideline with the addition of an examination by a neurologist, serum immunoglobulin G -glycan profiling and a brain MRI. The biomarkers of interest were galactose-1-phosphate levels and -glycan profiles, and the clinical outcomes studied were intellectual outcome and the presence or absence of movement disorders and/or primary ovarian insufficiency. Data of 56 classical galactosemia patients are reported. The intellectual outcome ranged from 45 to 103 (mean 77 ± 14) and was <85 in 62%. Movement disorders were found in 17 (47%) of the 36 tested patients. In females aged 12 years and older, primary ovarian insufficiency was diagnosed in 12 (71%) of the 17 patients. Significant differences in -glycan peaks were found between controls and patients. However, no significant differences in either -glycans or galactose-1-phosphate levels were found between patients with a poor (intellectual outcome < 85) and normal intellectual outcome (intellectual outcome ≥ 85), and with or without movement disorders or primary ovarian insufficiency. The variant patients detected by newborn screening, with previously unknown geno- and phenotypes and currently no long-term complications, demonstrated significantly lower galactose-1-phospate levels than classical patients ( < 0.0005). Qualitative analysis of the MRI's demonstrated brain abnormalities in 18 of the 21 patients, more severely in patients with a lower intellectual outcome and/or with movement disorders. This study demonstrates a large variability in clinical outcome, which varies from a below average intelligence, movement disorders and in females primary ovarian insufficiency to a normal clinical outcome. In our cohort of classical galactosemia patients, galactose-1-phosphate levels and -glycan variations were not associated with clinical outcomes, but galactose-1-phosphate levels did differentiate between classical and variant patients detected by newborn screening. The correlation between brain abnormalities and clinical outcome should be further investigated by quantitative analysis of the MR images. The variability in clinical outcome necessitates individual and standardized evaluation of all classical galactosemia patients.
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http://dx.doi.org/10.1093/braincomms/fcaa006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7425409PMC
January 2020

Correction to: Classical galactosemia: neuropsychological and psychosocial functioning beyond intellectual abilities.

Orphanet J Rare Dis 2020 09 7;15(1):238. Epub 2020 Sep 7.

Department of Pediatrics, room H7-270, Amsterdam University Medical Centre, MC, PO BOX 22660, 1100 DD, Amsterdam, The Netherlands.

An amendment to this paper has been published and can be accessed via the original article.
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http://dx.doi.org/10.1186/s13023-020-01447-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7487470PMC
September 2020

Galactokinase deficiency: lessons from the GalNet registry.

Genet Med 2021 Jan 18;23(1):202-210. Epub 2020 Aug 18.

Manton Center for Orphan Disease Research, Division of Genetics and Genomics, Boston Children's Hospital, Harvard Medical School, Boston, MA, USA.

Purpose: Galactokinase (GALK1) deficiency is a rare hereditary galactose metabolism disorder. Beyond cataract, the phenotypic spectrum is questionable. Data from affected patients included in the Galactosemias Network registry were collected to better characterize the phenotype.

Methods: Observational study collecting medical data of 53 not previously reported GALK1 deficient patients from 17 centers in 11 countries from December 2014 to April 2020.

Results: Neonatal or childhood cataract was reported in 15 and 4 patients respectively. The occurrence of neonatal hypoglycemia and infection were comparable with the general population, whereas bleeding diathesis (8.1% versus 2.17-5.9%) and encephalopathy (3.9% versus 0.3%) were reported more often. Elevated transaminases were seen in 25.5%. Cognitive delay was reported in 5 patients. Urinary galactitol was elevated in all patients at diagnosis; five showed unexpected Gal-1-P increase. Most patients showed enzyme activities ≤1%. Eleven different genotypes were described, including six unpublished variants. The majority was homozygous for NM_000154.1:c.82C>A (p.Pro28Thr). Thirty-five patients were diagnosed following newborn screening, which was clearly beneficial.

Conclusion: The phenotype of GALK1 deficiency may include neonatal elevation of transaminases, bleeding diathesis, and encephalopathy in addition to cataract. Potential complications beyond the neonatal period are not systematically surveyed and a better delineation is needed.
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http://dx.doi.org/10.1038/s41436-020-00942-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7790741PMC
January 2021

Evaluation of 11 years of newborn screening for maple syrup urine disease in the Netherlands and a systematic review of the literature: Strategies for optimization.

JIMD Rep 2020 Jul 13;54(1):68-78. Epub 2020 May 13.

Department of Pediatrics, Division of Metabolic Disorders Amsterdam UMC, University of Amsterdam Amsterdam The Netherlands.

Maple syrup urine disease (MSUD) leads to severe neurological deterioration unless diagnosed early and treated immediately. We have evaluated the effectiveness of 11 years of MSUD newborn screening (NBS) in the Netherlands (screening >72 hours, referral if both total leucine (Xle) and valine ≥400 μmol/L blood) and have explored possibilities for improvement by combining our data with a systematic literature review and data from Collaborative Laboratory Integrated Reports (CLIR). Dutch MSUD NBS characteristics and accuracy were determined. The hypothetical referral numbers in the Dutch population of additional screening markers suggested by CLIR were calculated. In a systematic review, articles reporting NBS leucine concentrations of confirmed patients were included. Our data showed that NBS of 1 963 465 newborns identified 4 MSUD patients and led to 118 false-positive referrals (PPV 3.28%; incidence 1:491 000 newborns). In literature, leucine is the preferred NBS parameter. Total leucine (Xle) concentrations (mass-spectrometry) of 53 detected and 8 false-negative patients (sampling age within 25 hours in 3 patients) reported in literature ranged from 288 to 3376 (median 900) and 42 to 325 (median 209) μmol/L blood respectively. CLIR showed increasing Xle concentrations with sampling age and early NBS sampling and milder variant MSUD phenotypes with (nearly) normal biochemical profiles are causes of false-negative NBS results. We evaluated the effect of additional screening markers and established the Xle/phenylalanine ratio as a promising additional marker ratio for increasing the PPV, while maintaining high sensitivity in the Dutch MSUD NBS.
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http://dx.doi.org/10.1002/jmd2.12124DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7358668PMC
July 2020

Critical evaluation of the newborn screening for congenital hypothyroidism in the Netherlands.

Eur J Endocrinol 2020 Sep;183(3):265-273

Endocrinology Laboratory, Department of Clinical Chemistry, Amsterdam Gastroenterology & Metabolism, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands.

Objective: Congenital hypothyroidism (CH) is defined as thyroid hormone deficiency at birth due to disorders of the thyroid gland (thyroidal CH, CH-T), or the hypothalamus or pituitary (central CH, CH-C). The Dutch Newborn Screening (NBS) strategy is primarily based on determination of thyroxine (T4) concentrations in dried blood spots followed, if necessary, by thyroid-stimulating hormone (TSH) and thyroxine-binding globulin (TBG) measurement enabling detection of both CH-T and CH-C. A calculated T4/TBG ratio serves as an indirect measure for free T4. A T4/TBG ratio ≤ 17 in a second heel puncture is suggestive of CH-C.

Design And Methods: In the present study, we evaluated 11 years of Dutch CH NBS using a database of referred cases by assessing the contribution of each criterion in the unique stepwise T4-TSH-TBG NBS algorithm.

Results: Between 2007 and the end of 2017, 1 963 465 newborns were screened in the Netherlands. Use of the stepwise algorithm led to 3044 referrals and the identification of 612 CH cases, consisting of 496 CH-T, 86 CH-C, and 30 CH of unknown origin diagnoses. We detected 62.8% of CH-C cases by the T4/TBG ratio in the second heel puncture. The positive predictive value (PPV) of the stepwise T4-TSH-TBG NBS algorithm was 21.0%.

Conclusion: This evaluation shows that the Dutch stepwise T4-TSH-TBG NBS algorithm with a calculated T4/TBG ratio is of great value for the detection of both CH-T and CH-C in the Netherlands, at the cost of a lower PPV compared to TSH-based NBS strategies.
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http://dx.doi.org/10.1530/EJE-19-1048DOI Listing
September 2020

Classical galactosemia: neuropsychological and psychosocial functioning beyond intellectual abilities.

Orphanet J Rare Dis 2020 02 7;15(1):42. Epub 2020 Feb 7.

Department of Pediatrics, room H7-270, Amsterdam University Medical Centre, MC, PO BOX 22660, 1100 DD, Amsterdam, The Netherlands.

Background: Despite early diagnosis and treatment, Classical Galactosemia (CG) patients frequently develop long-term complications, such as cognitive impairment. Available literature primarily reports on general intellectual abilities and shows a substantially lower Full Scale Intelligence Quotient (FSIQ) in CG patients than in the general population. Both problems in social functioning as well as internalizing problems are often reported in CG patients. The combination of intelligence, cognitive functioning, behavior and social functioning has not been studied systematically in CG patients.

Methods: To determine if CG patients demonstrate a specific neuropsychological and psychosocial profile, we investigated intelligence, functioning on multiple cognitive domains, behavior and social functioning with a comprehensive neuropsychological test battery and questionnaires (self- and proxy-reported).

Results: The data of 48 patients, aged 4-47 years are reported. FSIQ ranged from 45 to 103 (mean 77 ± 14). A negative correlation between age and FSIQ was demonstrated (p = 0.037) which resulted directly from the inclusion of four young 'milder' patients detected by newborn screening (NBS) with an expected better clinical outcome. Compared to normative data, patients had significantly lower but highly variable scores on all cognitive domains, especially on tests requiring mental speed. In the context of the FSIQ, 43% of the cognitive test results exceeded IQ based expectations. Overall, the patients' scores on social functioning were in the normal range but internalizing problems were frequently reported. In our cohort, an early initiation of dietary treatment due to NBS or family screening did not result in a more favorable neuropsychological outcome.

Conclusions: In this study, we demonstrated that as a cohort, CG patients have a below average intelligence and impaired cognitive functioning without a distinctive neuropsychological profile. The effect of age on neurocognitive functioning should be assessed in longitudinal studies. Social functioning was not impaired, but patients may be at risk for internalizing problems. Considering the large variability in cognitive, behavioral and social functioning and the finding that cognitive outcomes may exceed IQ based expectations, an individual evaluation and follow-up is warranted in all CG patients to ensure timely support if needed.
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http://dx.doi.org/10.1186/s13023-019-1277-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7007688PMC
February 2020

The Galactose Index measured in fibroblasts of GALT deficient patients distinguishes variant patients detected by newborn screening from patients with classical phenotypes.

Mol Genet Metab 2020 03 9;129(3):171-176. Epub 2020 Jan 9.

Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, the Netherlands. Electronic address:

Background: The high variability in clinical outcome of patients with Classical Galactosemia (CG) is poorly understood and underlines the importance of prognostic biomarkers, which are currently lacking. The aim of this study was to investigate if residual galactose metabolism capacity is associated with clinical and biochemical outcomes in CG patients with varying geno- and phenotypes.

Methods: Galactose Metabolite Profiling (GMP) was used to determine residual galactose metabolism in fibroblasts of CG patients. The association between the galactose index (GI) defined as the ratio of the measured metabolites [UC]Gal-1-P/ [C]UDP-galactose, and both intellectual and neurological outcome and galactose-1-phosphate (Gal-1-P) levels was investigated.

Results: GMP was performed in fibroblasts of 28 patients and 3 control subjects. The GI of the classical phenotype patients (n = 22) was significantly higher than the GI of four variant patients detected by newborn screening (NBS) (p = .002), two homozygous p.Ser135Leu patients (p = .022) and three controls (p = .006). In the classical phenotype patients, 13/18 (72%) had a poor intellectual outcome (IQ < 85) and 6/12 (50%) had a movement disorder. All the NBS detected variant patients (n = 4) had a normal intellectual outcome (IQ ≥ 85) and none of them has a movement disorder. In the classical phenotype patients, there was no significant difference in GI between patients with a poor and normal clinical outcome. The NBS detected variant patients had significantly lower GI levels and thus higher residual galactose metabolism than patients with classical phenotypes. There was a clear correlation between Gal-1-P levels in erythrocytes and the GI (p = .001).

Conclusions: The GI was able to distinguish CG patients with varying geno- and phenotypes and correlated with Gal-1-P. The data of the NBS detected variant patients demonstrated that a higher residual galactose metabolism may result in a more favourable clinical outcome. Further research is needed to enable individual prognostication and treatment in all CG patients.
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http://dx.doi.org/10.1016/j.ymgme.2020.01.002DOI Listing
March 2020

The 1- C galactose breath test in GALT deficient patients distinguishes NBS detected variant patients but does not predict outcome in classical phenotypes.

J Inherit Metab Dis 2020 05 22;43(3):507-517. Epub 2020 Jan 22.

Department of Pediatrics, Division of Metabolic Disorders, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Amsterdam, The Netherlands.

Classical galactosemia (CG) patients frequently develop long-term complications despite early dietary treatment. The highly variable clinical outcome is poorly understood and a lack of prognostic biomarkers hampers individual prognostication and treatment. The aim of this study was to investigate the association between residual galactose oxidation capacity and clinical and biochemical outcomes in CG patients with varying geno- and phenotypes. The noninvasive 1- C galactose breath test was used to assess whole body galactose oxidation capacity. Participants received a 7 mg/kg oral dose of 1- C labelled galactose. The galactose oxidation capacity was determined by calculating the cumulative percentage dose of the administered galactose (CUMPCD) recovered as CO in exhaled air. Forty-one CG patients (5-47 years) and four adult controls were included. The median galactose oxidation capacity after 120 minutes (CUMPCDT120) of 34 classical patients (0.29; 0.08-7.51) was significantly lower when compared to two homozygous p.Ser135Leu patients (9.44; 8.66-10.22), one heterozygous p.Ser135Leu patient 18.59, four NBS detected variant patients (13.79; 12.73-14.87) and four controls (9.29; 8.94-10.02). There was a clear correlation between Gal-1-P levels and CUMPCDT120 (P < .0005). In the classical patients, the differences in CUMPCDT120 were small and did not distinguish between patients with poor and normal clinical outcomes. The galactose breath test distinguished classical patients from homo- and heterozygous p.Ser135Leu and NBS detected variant patients, but was not able to predict clinical outcomes in classical patients. Future studies are warranted to enable individualised prognostication and treatment, especially in NBS variants with galactose oxidation capacities in the control range.
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http://dx.doi.org/10.1002/jimd.12207DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317391PMC
May 2020

Retrospective evaluation of the Dutch pre-newborn screening cohort for propionic acidemia and isolated methylmalonic acidemia: What to aim, expect, and evaluate from newborn screening?

J Inherit Metab Dis 2020 05 22;43(3):424-437. Epub 2019 Dec 22.

Section Metabolic Diseases, Department of Child Health, Wilhelmina Children's Hospital, University Medical Centre Utrecht, Utrecht University, Utrecht, The Netherlands.

Evidence for effectiveness of newborn screening (NBS) for propionic acidemia (PA) and isolated methylmalonic acidemia (MMA) is scarce. Prior to implementation in the Netherlands, we aim to estimate the expected health gain of NBS for PA and MMA. In this national retrospective cohort study, the clinical course of 76/83 Dutch PA and MMA patients, diagnosed between January 1979 and July 2019, was evaluated. Five clinical outcome parameters were defined: adverse outcome of the first symptomatic phase, frequency of acute metabolic decompensations (AMD), cognitive function, mitochondrial complications, and treatment-related complications. Outcomes of patients identified by family testing were compared with the outcomes of their index siblings. An adverse outcome due to the first symptomatic phase was recorded in 46% of the clinically diagnosed patients. Outcome of the first symptomatic phase was similar in 5/9 sibling pairs and better in 4/9 pairs. Based on the day of diagnosis of the clinically diagnosed patients and sibling pair analysis, a preliminary estimated reduction of adverse outcome due to the first symptomatic phase from 46% to 36%-38% was calculated. Among the sibling pairs, AMD frequency, cognitive function, mitochondrial, and treatment-related complications were comparable. These results suggest that the health gain of NBS for PA and MMA in overall outcome may be limited, as only a modest decrease of adverse outcomes due to the first symptomatic phase is expected. With current clinical practice, no reduced AMD frequency, improved cognitive function, or reduced frequency of mitochondrial or treatment-related complications can be expected.
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http://dx.doi.org/10.1002/jimd.12193DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317354PMC
May 2020

Reducing complexity: explaining inborn errors of metabolism and their treatment to children and adolescents.

Orphanet J Rare Dis 2019 11 8;14(1):248. Epub 2019 Nov 8.

Division of Metabolism, University Children's Hospital Zurich, Zurich, Switzerland.

Background: Inborn errors of metabolism (IEM) are a group of rare, heterogeneous and complex genetic conditions. Clinically, IEM often affect the central nervous system and other organs. Some carry the risk of progression and / or potentially life-threatening crises. Many patients have to adhere to lifelong dietary or drug treatment. The complexity of IEM makes it difficult for patients and caregivers to understand their pathophysiology, inheritance and therapy rationale. Especially patients reaching adolescence may have only limited knowledge of their condition since medical care has often entirely been handled by their parents. Knowledge about disease and treatment, however, constitute pillars of self-responsible disease management. Not many standardized patient education materials on IEM are available and their comprehensibility has not been systematically investigated.

Methods: We developed and tested patient education materials for school-aged children and adolescents with IEM. Informative texts and illustrations in paper form and as videos were developed by an international network of metabolic care professionals together with a graphic artist and experts for easy-to-read language. The materials were presented in standardized single or group training sessions to 111 individuals; first, to 74 healthy children and adolescents (recruited via public schools) and consecutively to 37 paediatric patients with IEM (phenylketonuria, galactosemia, urea cycle defects, lysosomal storage disorders) from six metabolic centres. Knowledge-gain was assessed by pre- and post-testing.

Results: Knowledge-gain was significant in healthy children and adolescents as well as in patients (p < .001, r =. -77 /. -70). Effect sizes were large in both groups (r = -.77 / -.70). This result was independent from family language and teacher-rated concentration or cognitive capacity in healthy children.

Conclusion: The newly developed patient education materials are a powerful tool to improve disease- and treatment-related knowledge. They facilitate communication between the medical team and children and adolescents with IEM and their caregivers.
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http://dx.doi.org/10.1186/s13023-019-1236-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6842257PMC
November 2019

Cognitive functioning in patients with classical galactosemia: a systematic review.

Orphanet J Rare Dis 2019 10 18;14(1):226. Epub 2019 Oct 18.

Department of Medical Psychology, Amsterdam UMC - location AMC, P.O. Box 22660, 1100 DD, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands.

Background: Patients with the metabolic disorder classical galactosemia suffer from long-term complications despite a galactose-restricted diet, including a below average intelligence level. The aim of the current review was to investigate the incidence and profile of cognitive impairments in patients with classical galactosemia.

Method: MEDLINE, EMBASE and PsychINFO were searched up to 23 October 2018 for studies examining information processing speed, attention, memory, language, visuospatial functioning, executive functioning and social cognition in patients with confirmed classical galactosemia utilizing standardized neuropsychological tests. Data synthesis followed a narrative approach, since the planned meta-analysis was not possible due to large variability between the neuropsychological assessments.

Results: Eleven studies were included, including case-studies. The quality of most studies was moderate to low. As a group, patients with classical galactosemia exhibit below average to low scores on all cognitive domains. A large proportion of the patients perform on an impaired level on attention, memory and vocabulary. Evidence for impairments in information processing speed, language, visuospatial functioning and aspects of executive functioning was limited due to the small number of studies investigating these cognitive functions. Social cognition was not examined at all.

Conclusions: Given the moderate to low quality of the included studies and the limited evidence in many cognitive domains, the incidence of cognitive impairment in patients with classical galactosemia is not yet clear. Both clinicians and researchers encountering patients with classical galactosemia need to be aware of possible cognitive impairments. Future well-designed studies are needed to determine the cognitive profile of classical galactosemia. This can be the basis for the development of intervention strategies.
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http://dx.doi.org/10.1186/s13023-019-1215-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6798502PMC
October 2019

Bone mineral density is within normal range in most adult phenylketonuria patients.

J Inherit Metab Dis 2020 03 6;43(2):251-258. Epub 2020 Feb 6.

Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC - Location AMC, Amsterdam, The Netherlands.

Low bone mineral density (BMD) as a risk factor for fractures has been a long-standing concern in phenylketonuria (PKU). It is hypothesised that the disease itself or the dietary treatment might lead to a low BMD. Previous studies show conflicting results of BMD in PKU due to differences in age, techniques to assess BMD and criteria used. To assess the prevalence of low BMD and define possible risk factors in a large number of adult, early treated PKU (ETPKU) patients. European centres were invited for a survey, collecting retrospective data including results of dual-energy X-ray absorptiometry (DXA) scans of adult ETPKU patients. BMD of 183 adult ETPKU patients aged 18-46 (median age 28, all females premenopausal) years was lower than in the general population at most skeletal sites but the frequency of low BMD (Z-score <-2) was at maximum 5.5%. No risk factors for low BMD in PKU patients could be identified. Low BMD occurs only in a small subset of PKU patients. DXA scans should be considered for well controlled patients from age 35-40 years and up and on indication in those PKU patients considered to be at increased risk for fractures.
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http://dx.doi.org/10.1002/jimd.12177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7078943PMC
March 2020

Prediction of disease severity in multiple acyl-CoA dehydrogenase deficiency: A retrospective and laboratory cohort study.

J Inherit Metab Dis 2019 09 17;42(5):878-889. Epub 2019 Jul 17.

Division of Metabolic Diseases, Beatrix Children's Hospital, University Medical Center Groningen, University of Groningen, Groningen, the Netherlands.

Multiple acyl-CoA dehydrogenase deficiency (MADD) is an ultra-rare inborn error of mitochondrial fatty acid oxidation (FAO) and amino acid metabolism. Individual phenotypes and treatment response can vary markedly. We aimed to identify markers that predict MADD phenotypes. We performed a retrospective nationwide cohort study; then developed an MADD-disease severity scoring system (MADD-DS3) based on signs and symptoms with weighed expert opinions; and finally correlated phenotypes and MADD-DS3 scores to FAO flux (oleate and myristate oxidation rates) and acylcarnitine profiles after palmitate loading in fibroblasts. Eighteen patients, diagnosed between 1989 and 2014, were identified. The MADD-DS3 entails enumeration of eight domain scores, which are calculated by averaging the relevant symptom scores. Lifetime MADD-DS3 scores of patients in our cohort ranged from 0 to 29. FAO flux and [U- C]C2-, C5-, and [U- C]C16-acylcarnitines were identified as key variables that discriminated neonatal from later onset patients (all P < .05) and strongly correlated to MADD-DS3 scores (oleate: r = -.86; myristate: r = -.91; [U- C]C2-acylcarnitine: r = -.96; C5-acylcarnitine: r = .97; [U- C]C16-acylcarnitine: r = .98, all P < .01). Functional studies in fibroblasts were found to differentiate between neonatal and later onset MADD-patients and were correlated to MADD-DS3 scores. Our data may improve early prediction of disease severity in order to start (preventive) and follow-up treatment appropriately. This is especially relevant in view of the inclusion of MADD in population newborn screening programs.
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http://dx.doi.org/10.1002/jimd.12147DOI Listing
September 2019

Limited data to evaluate real-world effectiveness of enzyme replacement therapy for mucopolysaccharidosis type I.

J Inherit Metab Dis 2019 09 16;42(5):762-775. Epub 2019 May 16.

Amsterdam UMC, University of Amsterdam, Pediatric Metabolic Diseases, Emma Children's Hospital, Meibergdreef 9, Amsterdam, Netherlands.

Orphan medicinal products (OMPs) are often authorized based on pivotal phase II and III trials that do not always meet high quality criteria. Laronidase is an example of an OMP used for treatment of mucopolysaccharidosis I (MPS I). One randomized controlled trial demonstrated efficacy on several somatic symptoms. However, effectiveness in the real-world setting remains to be determined. We performed a systematic review to evaluate the effectiveness of enzyme replacement therapy (ERT) on clinically relevant outcomes in MPS I. A search in OVID MEDLINE and OVID EMBASE was performed. Postmarketing studies including MPS I patients treated with ERT and reporting data on any of 19 predefined clinical outcome measures obtained before the start of ERT and at follow-up were eligible. Three scenarios were used to define effectiveness of ERT. The first scenario (A) assumes that improvement is essential, while the second scenario (B) also includes stabilization of signs and symptoms. The third scenario (C) defines failure of therapy. Twenty case series were included. The criteria indicating effectiveness (A), were met for four of 19 outcome measures while the criteria, indicating unclear effectiveness (B) were met for five of 19. For one of 19 nonverifiable data were reported and for nine of 19 no overall conclusions could be drawn (ambiguous results). Real-world effectiveness of laronidase is extremely difficult to assess, 15 years after marketing authorization. This is partially due to insufficient natural history data. We recommend the conduct of rigorous and independent postmarketing studies including core outcome sets for OMPs, enforced by marketing and/or reimbursing authorities aiming to demonstrate real-world effectiveness within a reasonable time frame.
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http://dx.doi.org/10.1002/jimd.12103DOI Listing
September 2019

A nationwide retrospective observational study of population newborn screening for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency in the Netherlands.

J Inherit Metab Dis 2019 09 16;42(5):890-897. Epub 2019 May 16.

Section of Metabolic Diseases, Beatrix Children's Hospital, University Medical Centre Groningen, University of Groningen, Groningen, The Netherlands.

To evaluate the Dutch newborn screening (NBS) for medium-chain acyl-CoA dehydrogenase (MCAD) deficiency since 2007, a nationwide retrospective, observational study was performed of clinical, laboratory and epidemiological parameters of patients with MCAD deficiency born between 2007 and 2015. Severe MCAD deficiency was defined by ACADM genotypes associated with clinical ascertainment, or variant ACADM genotypes with a residual MCAD enzyme activity <10%. Mild MCAD deficiency was defined by variant ACADM genotypes with a residual MCAD enzyme activity ≥10%. The prevalence of MCAD deficiency was 1/8300 (95% CI: 1/7300-1/9600). Sensitivity of the Dutch NBS was 99% and specificity ~100%, with a positive predictive value of 86%. Thirteen newborns with MCAD deficiency suffered from neonatal symptoms, three of them died. Of the 189 identified neonates, 24% had mild MCAD deficiency. The acylcarnitine ratio octanoylcarnitine (C8)/decanoylcarnitine (C10) was superior to C8 in discriminating between mild and severe cases and more stable in the first days of life. NBS for MCAD deficiency has a high sensitivity, specificity, and positive predictive value. In the absence of a golden standard to confirm the diagnosis, the combination of acylcarnitine (ratios), molecular and enzymatic studies allows risk stratification. To improve evaluation of NBS protocols and clinical guidelines, additional use of acylcarnitine ratios and multivariate pattern-recognition software may be reappraised in the Dutch situation. Prospective recording of NBS and follow-up data is warranted covering the entire health care chain of preventive and curative medicine.
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http://dx.doi.org/10.1002/jimd.12102DOI Listing
September 2019

Movement disorders and nonmotor neuropsychological symptoms in children and adults with classical galactosemia.

J Inherit Metab Dis 2019 05 27;42(3):451-458. Epub 2019 Feb 27.

Department of Neurology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.

Although movement disorders (MDs) are known complications, the exact frequency and severity remains uncertain in patients with classical galactosemia, especially in children. We determined the frequency, classification and severity of MDs in a cohort of pediatric and adult galactosemia patients, and assessed the association with nonmotor neuropsychological symptoms and daily functioning. Patients from seven centers in the United Kingdom and the Netherlands with a confirmed galactosemia diagnosis were invited to participate. A videotaped neurological examination was performed and an expert panel scored the presence, classification and severity of MDs. Disease characteristics, nonmotor neuropsychological symptoms, and daily functioning were evaluated with structured interviews and validated questionnaires (Achenbach, Vineland, Health Assessment Questionnaire, SIP68). We recruited 37 patients; 19 adults (mean age 32.6 years) and 18 children (mean age 10.7 years). Subjective self-reports revealed motor symptoms in 19/37 (51.4%), similar to the objective (video) assessment, with MDs in 18/37 patients (48.6%). The objective severity scores were moderate to severe in one third (6/37). Dystonia was the overall major feature, with additional tremor in adults, and myoclonus in children. Behavioral or psychiatric problems were present in 47.2%, mostly internalizing problems, and associated with MDs. Daily functioning was significantly impaired in the majority of patients. Only one patient received symptomatic treatment for MDs. We show that MDs and nonmotor neuropsychological symptoms are frequent in both children and adults with classical galactosemia.
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http://dx.doi.org/10.1002/jimd.12054DOI Listing
May 2019

An update on the genetics, clinical presentation, and pathomechanisms of human riboflavin transporter deficiency.

J Inherit Metab Dis 2019 07 21;42(4):598-607. Epub 2019 Feb 21.

MRC Centre for Neuromuscular Diseases, Department of Neuromuscular Diseases, UCL Queen Square Institute of Neurology and National Hospital for Neurology and Neurosurgery, London, UK.

Riboflavin transporter deficiency (RTD) is a rare neurological condition that encompasses the Brown-Vialetto-Van Laere and Fazio-Londe syndromes since the discovery of pathogenic mutations in the SLC52A2 and SLC52A3 genes that encode human riboflavin transporters RFVT2 and RFVT3. Patients present with a deteriorating progression of peripheral and cranial neuropathy that causes muscle weakness, vision loss, deafness, sensory ataxia, and respiratory compromise which when left untreated can be fatal. Considerable progress in the clinical and genetic diagnosis of RTDs has been made in recent years and has permitted the successful lifesaving treatment of many patients with high dose riboflavin supplementation. In this review, we first outline the importance of riboflavin and its efficient transmembrane transport in human physiology. Reports on 109 patients with a genetically confirmed diagnosis of RTD are then summarized in order to highlight commonly presenting clinical features and possible differences between patients with pathogenic SLC52A2 (RTD2) or SLC52A3 (RTD3) mutations. Finally, we focus attention on recent work with different models of RTD that have revealed possible pathomechanisms contributing to neurodegeneration in patients.
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http://dx.doi.org/10.1002/jimd.12053DOI Listing
July 2019

Impact of newborn screening for very-long-chain acyl-CoA dehydrogenase deficiency on genetic, enzymatic, and clinical outcomes.

J Inherit Metab Dis 2019 05 8;42(3):414-423. Epub 2019 Apr 8.

Department of Metabolic Diseases, Dutch Fatty Acid Oxidation Expertise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht, Utrecht, The Netherlands.

Most infants with very-long-chain acyl-CoA dehydrogenase deficiency (VLCADD) identified by newborn screening (NBS) are asymptomatic at the time of diagnosis and remain asymptomatic. If this outcome is due to prompt diagnosis and initiation of therapy, or because of identification of individuals with biochemical abnormalities who will never develop symptoms, is unclear. Therefore, a 10-year longitudinal national cohort study of genetically confirmed VLCADD patients born before and after introduction of NBS was conducted. Main outcome measures were clinical outcome parameters, acyl-CoA dehydrogenase very long chain gene analysis, VLCAD activity, and overall capacity of long-chain fatty acid oxidation (LC-FAO flux) in lymphocytes and cultured skin fibroblasts. Median VLCAD activity in lymphocytes of 54 patients, 21 diagnosed pre-NBS and 33 by NBS was, respectively, 5.4% (95% confidence interval [CI]: 4.0-8.3) and 12.6% (95% CI: 10.7-17.7; P < 0.001) of the reference mean. The median LC-FAO flux was 33.2% (95% CI: 22.8-48.3) and 41% (95% CI: 40.8-68; P < 0.05) of the control mean, respectively. Clinical characteristics in 23 pre-NBS and 37 NBS patients revealed hypoglycemic events in 12 vs 2 patients, cardiomyopathy in 5 vs 4 patients and myopathy in 14 vs 3 patients. All patients with LC-FAO flux <10% developed symptoms. Of the patients with LC-FAO flux >10% 7 out of 12 diagnosed pre-NBS vs none by NBS experienced hypoglycemic events. NBS has a clear beneficial effect on the prevention of hypoglycemic events in patients with some residual enzyme activity, but does not prevent hypoglycemia nor cardiac complications in patients with very low residual enzyme activity. The effect of NBS on prevalence and prevention of myopathy-related complications remains unclear.
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http://dx.doi.org/10.1002/jimd.12075DOI Listing
May 2019

Proposal for an individualized dietary strategy in patients with very long-chain acyl-CoA dehydrogenase deficiency.

J Inherit Metab Dis 2019 01;42(1):159-168

Department of Metabolic Diseases, Dutch Fatty Acid Oxidation Expertise Center, Wilhelmina Children's Hospital (UMCU), University Medical Center Utrecht, Internal Mail KE 04.306.0, PO Box 85090 3508 AB, Utrecht, Netherlands.

Background: Patients with very long chain acyl-CoA dehydrogenase deficiency (VLCADD), a long chain fatty acid oxidation disorder, are traditionally treated with a long chain triglyceride (LCT) restricted and medium chain triglyceride (MCT) supplemented diet. Introduction of VLCADD in newborn screening (NBS) programs has led to the identification of asymptomatic newborns with VLCADD, who may have a more attenuated phenotype and may not need dietary adjustments.

Objective: To define dietary strategies for individuals with VLCADD based on the predicted phenotype.

Method: We evaluated long-term dietary histories of a cohort of individuals diagnosed with VLCADD identified before the introduction of VLCADD in NBS and their beta-oxidation (LC-FAO) flux score (rate of oleate oxidation) in cultured skin fibroblasts in relation to the clinical outcome. Based on these results a dietary strategy is proposed.

Results: Sixteen individuals with VLCADD were included. One had an LC-FAO flux score >90%, was not on a restricted diet and is asymptomatic to date. Four patients had an LC-FAO flux score <10%, and significant VLCADD related symptoms despite the use of strict diets including LCT restriction, MCT supplementation and nocturnal gastric drip feeding. Patients with an LC-FAO flux score between 10 and 90% (n = 11) showed a more heterogeneous phenotype.

Conclusions: This study shows that a strict diet cannot prevent poor clinical outcome in severely affected patients and that the LC-FAO flux is a good predictor of clinical outcome in individuals with VLCADD identified before its introduction in NBS. Hereby, we propose an individualized dietary strategy based on the LC-FAO flux score.
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http://dx.doi.org/10.1002/jimd.12037DOI Listing
January 2019

Screening for lysosomal acid lipase deficiency: A retrospective data mining study and evaluation of screening criteria.

Atherosclerosis 2018 11 19;278:174-179. Epub 2018 Sep 19.

Department of Pediatric Gastroenterology and Nutrition, Amsterdam University Medical Centers, Location Academic Medical Center/Emma Children's Hospital, the Netherlands.

Background And Aims: Lysosomal acid lipase deficiency (LAL-D) is a lysosomal storage disorder. In severe cases, it can cause life-threatening organ failure due to lipid substrates accumulation. However, mild phenotypes of this disorder are increasingly recognized. The aim of this study is to determine the number of missed LAL-D patients in a large pediatric hospital population.

Methods: In a retrospective data mining study, the medical files of children, who visited the outpatient clinic at a university hospital between 2000 and 2016, with high plasma low density lipoprotein cholesterol (LDL-C) levels, were evaluated. Previously developed LAL-D screening criteria, with lipid and alanine aminotransferase (ALT) values adjusted for children, were used to analyze which children are suspect for LAL-D. For suspicion of LAL-D, at least 3 out of 5 screening criteria had to be met. Subsequently data on presentation and follow-up were collected to determine if the clinical picture was compatible with LAL-D.

Results: We identified 2037 children with high LDL-C levels. Of those, 36 children complied with ≥3 screening criteria. Thirty-one of those had an underlying disorder other than LAL-D that explained the abnormalities and, in the 5 remaining children, ALT and lipid levels normalized spontaneously, thus excluding LAL-D.

Conclusions: This study shows that retrospective data mining is unlikely to yield a significant number of LAL-D cases in children. The screening algorithm adjusted for children seems useful and accurate in the selection of children for further testing, suggesting it can be applied prospectively, although further validation is warranted.
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http://dx.doi.org/10.1016/j.atherosclerosis.2018.09.023DOI Listing
November 2018

Galactosaemia - should it be screened in newborns?

Authors:
Annet M Bosch

Dev Period Med 2018;22(3):221-224

Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Department of Pediatric Metabolic Disorders, Amsterdam, the Netherlands.

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September 2019

Fertility in classical galactosaemia, a study of N-glycan, hormonal and inflammatory gene interactions.

Orphanet J Rare Dis 2018 09 19;13(1):164. Epub 2018 Sep 19.

Department of Paediatrics, Trinity College, Dublin, Ireland.

Background: Classical Galactosaemia (CG) (OMIM #230400) is a rare inborn error of galactose metabolism caused by deficiency of the enzyme galactose-1-phosphate uridylyltransferase (GALT). Long-term complications persist in treated patients despite dietary galactose restriction with significant variations in outcomes suggesting epigenetic glycosylation influences. Primary Ovarian Insufficiency (POI) is a very significant complication affecting females with follicular depletion noted in early life. We studied specific glycan synthesis, leptin system and inflammatory gene expression in white blood cells as potential biomarkers of infertility in 54 adults with CG adults (27 females and 27 males) (age range 17-51 yr) on a galactose-restricted diet in a multi-site Irish and Dutch study. Gene expression profiles were tested for correlation with a serum Ultra-high Performance Liquid Chromatography (UPLC)-Immunoglobulin (IgG)-N-glycan galactose incorporation assay and endocrine measurements.

Results: Twenty five CG females (93%) had clinical and biochemical evidence of POI. As expected, the CG female patients, influenced by hormone replacement therapy, and the healthy controls of both genders showed a positive correlation between log leptin and BMI but this correlation was not apparent in CG males. The strongest correlations between serum leptin levels, hormones, G-ratio (galactose incorporation assay) and gene expression data were observed between leptin, its gene and G-Ratios data (r = - 0.68) and (r = - 0.94) respectively with lower circulating leptin in CG patients with reduced IgG galactosylation. In CG patients (males and females analysed as one group), the key glycan synthesis modifier genes MGAT3 and FUT8, which influence glycan chain bisecting and fucosylation and subsequent cell signalling and adhesion, were found to be significantly upregulated (p < 0.01 and p < 0.05) and also the glycan synthesis gene ALG9 (p < 0.01). Both leptin signalling genes LEP and LEPR were found to be upregulated (p < 0.01) as was the inflammatory genes ANXA1 and ICAM1 and the apoptosis gene SEPT4 (p < 0.01).

Conclusions: These results validate our previous findings and provide novel experimental evidence for dysregulation of genes LEP, LEPR, ANXA1, ICAM1 and SEPT4 for CG patients and combined with our findings of abnormalities of IgG glycosylation, hormonal and leptin analyses elaborate on the systemic glycosylation and cell signalling abnormalities evident in CG which likely influence the pathophysiology of POI.
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http://dx.doi.org/10.1186/s13023-018-0906-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6146524PMC
September 2018

Coenzyme Q10 deficiency due to a COQ4 gene defect causes childhood-onset spinocerebellar ataxia and stroke-like episodes.

Mol Genet Metab Rep 2018 Dec 13;17:19-21. Epub 2018 Sep 13.

Department of Pediatrics, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, the Netherlands.

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http://dx.doi.org/10.1016/j.ymgmr.2018.09.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138878PMC
December 2018

Profiling of intracellular metabolites produced from galactose and its potential for galactosemia research.

Orphanet J Rare Dis 2018 08 24;13(1):146. Epub 2018 Aug 24.

Department of Pediatrics, Emma Children's Hospital, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105, AZ, Amsterdam, The Netherlands.

Background: Clinical outcome of patients with a classical presentation of galactosemia (classical patients) varies substantially, even between patients with the same genotype. With current biomarkers, it is not possible to predict clinical outcome early in life. The aim of this study was to develop a method to provide more insight into galactose metabolism, which allows quantitative assessment of residual galactose metabolism in galactosemia patients. We therefore developed a method for galactose metabolite profiling (GMP) in fibroblasts using [U-C]-labeled galactose.

Methods: GMP analysis was performed in fibroblasts of three classical patients, three variant patients and three healthy controls. The following metabolites were analyzed: [UC]-galactose, [UC]-galactose-1-phosphate (Gal-1-P) and [C]- uridine diphosphate(UDP)-galactose. The ratio of [UC]-Gal-1-P/ [C]-UDP-galactose was defined as the galactose index (GI).

Results: All patient cell lines could be distinguished from the control cell lines and there was a clear difference between variant and classical patients. Variant patients had lower levels of [UC]-galactose and [UC]-Gal-1-P than classical patients (though substantially higher than healthy controls) and higher levels of [C]-UDP-galactose than classical patients (though substantially lower than healthy controls) resulting in a different GI in all groups.

Conclusions: GMP in fibroblasts is a sensitive method to determine residual galactose metabolism capacity, which can discriminate between patients with a classical presentation of galactosemia, patients with a variant presentation and healthy controls. GMP may be a useful method for early prognostication after further validation in a larger cohort of patients representing the full phenotypic spectrum of galactosemia.
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http://dx.doi.org/10.1186/s13023-018-0888-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6109347PMC
August 2018

The impact of metabolic control and tetrahydrobiopterin treatment on health related quality of life of patients with early-treated phenylketonuria: A PKU-COBESO study.

Mol Genet Metab 2018 09 7;125(1-2):96-103. Epub 2018 Jul 7.

Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, the Netherlands.

The aim of this study was to examine Health-Related Quality of Life (HRQoL) of patients with Phenylketonuria (PKU) in three different age groups and to investigate the impact of metabolic control and tetrahydrobiopterin (BH4) treatment on HRQoL of these patients. Participants were 90 early-treated patients aged 7 to 40 years (M = 21.0, SD = 10.1) and 109 controls aged 7 to 40.8 years (M = 19.4, SD = 8.6). HRQoL was assessed with the (generic) TNO-AZL questionnaires. Overall, good HRQoL was reported for children below 12 years of age, although they were judged to be less autonomic than their healthy counterparts. Adolescents aged 12-15 years showed poorer HRQoL in the domain "cognitive functioning" compared to controls. For adults ≥16 years, poorer age-controlled HRQoL was found for the domains cognition, depressive moods, and anger, with a further trend for the domain "pain". With respect to metabolic control, only for adult PKU-patients robust associations were observed, indicating poorer functioning, most notably in the domains cognition, sleep, pain, sexuality and anger, with higher historical and concurrent Phe-levels. With respect to BH4-use, effects on HRQoL were again only observed for adult PKU-patients. After controlling for age and historical Phe-levels, small but significant differences in favor of adult BH4-users compared to non-users were observed for HRQoL-categories happiness, anger, and social functioning. Together, these results show that, particularly for adult PKU-patients, HRQoL-problems are evident and that many of these problems are related to (history of) metabolic control. Beneficial effects of BH4-use appear to be limited to those associated with relief from the practical burdens related to the strict dietary treatment regimen, i.e. general mood and sociability, whereas metabolic control is more strongly related to basic physical and cognitive functioning.
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http://dx.doi.org/10.1016/j.ymgme.2018.07.002DOI Listing
September 2018

The need for additional care in patients with classical galactosaemia.

Disabil Rehabil 2019 11 31;41(22):2663-2668. Epub 2018 May 31.

Department of Pediatrics, Academic Medical Center , Amsterdam , The Netherlands.

Classical galactosaemia is an inborn error of galactose metabolism which may lead to impairments in body functions and accordingly, need for additional care. The primary aim of this study was to establish the type and intensity of this additional care. Patients with classical galactosaemia aged ≥2 years were evaluated with the Capacity Profile, a standardised method to classify additional care needs according to type and intensity. Based on a semi-structured interview, current impairments in five domains of body functions were determined. The intensity of additional care was assessed (from 0, usual care, to 5, total dependence). Forty-four patients with classical galactosaemia, 18 males and 26 females (median age 15 years, range 2-49 years), were included. There was a wide spectrum of impairments in mental functions. Motor function impairments were present in four patients, and mild speech impairments in eight patients. Additional care for sensory functions was uncommon. All patients needed a diet, which care is scored in the physical health domain. Apart from the diet all patients need, classical galactosaemia leads to the need for additional care mainly in the domains of mental functions and speech and voice functions. Implications for rehabilitation The Capacity Profile is a useful tool to demonstrate additional care needs in classical galactosaemia. In classical galactosaemia additional care is mostly indicated by mental impairments and speech and voice functions. One-fifth of patients have impairment of speech and voice functions at time of the study, and half of all patients had received speech therapy in childhood. Over 70% of patients need additional care/help due to impairment of mental functions, ranging from coaching due to social vulnerability to full day care.
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http://dx.doi.org/10.1080/09638288.2018.1475514DOI Listing
November 2019

Recommendations for newborn screening for galactokinase deficiency: A systematic review and evaluation of Dutch newborn screening data.

Mol Genet Metab 2018 05 21;124(1):50-56. Epub 2018 Mar 21.

Department of Pediatrics, Division of Metabolic Disorders, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. Electronic address:

Introduction: Galactokinase (GALK) deficiency causes cataract leading to severe developmental consequences unless treated early. Because of the easy prevention and rapid reversibility of cataract with treatment, the Dutch Health Council advised to include GALK deficiency in the Dutch newborn screening program. The aim of this study is to establish the optimal screening method and cut-off value (COV) for GALK deficiency screening by performing a systematic review of the literature of screening strategies and total galactose (TGAL) values and by evaluating TGAL values in the first week of life in a cohort of screened newborns in the Netherlands.

Methods: Systematic literature search strategies in OVID MEDLINE and OVID EMBASE were developed and study selection, data collection and analyses were performed by two independent investigators. A range of TGAL values measured by the Quantase Neonatal Total Galactose screening assay in a cohort of Dutch newborns in 2007 was evaluated.

Results: Eight publications were included in the systematic review. All four studies describing screening strategies used TGAL as the primary screening marker combined with galactose-1-phosphate uridyltransferase (GALT) measurement that is used for classical galactosemia screening. TGAL COVs of 2200 μmol/L, 1665 μmol/L and 1110 μmol/L blood resulted in positive predictive values (PPV) of 100%, 82% and 10% respectively. TGAL values measured in the newborn period were reported for 39 GALK deficiency patients with individual values ranging from 3963 to 8159 μmol/L blood and 2 group values with mean 8892 μmol/L blood (SD ± 5243) and 4856 μmol/L blood (SD ± 461). Dutch newborn screening data of 72,786 newborns from 2007 provided a median TGAL value of 110 μmol/L blood with a range of 30-2431 μmol/L blood.

Conclusion: Based on TGAL values measured in GALK deficiency patients reported in the literature and TGAL measurements in the Dutch cohort by newborn screening we suggest to perform the GALK screening with TGAL as a primary marker with a COV of 2500 μmol/L blood, combined with GALT enzyme activity measurement as used in the classical galactosemia screening, to ensure detection of GALK deficiency patients and minimize false positive referrals.
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http://dx.doi.org/10.1016/j.ymgme.2018.03.008DOI Listing
May 2018

Response to the Letter to the Editor Regarding "Micronutrients, Essential Fatty Acids and Bone Health in Phenylketonuria".

Ann Nutr Metab 2018 16;72(1):80-81. Epub 2018 Jan 16.

Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands.

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http://dx.doi.org/10.1159/000486185DOI Listing
August 2019