Publications by authors named "Encarna Guillén-Navarro"

60 Publications

Health impact of acute intermittent porphyria in latent and non-recurrent attacks patients.

Orphanet J Rare Dis 2021 02 27;16(1):106. Epub 2021 Feb 27.

Instituto Murciano de Investigación Biosanitaria Virgen de la Arrixaca (IMIB-Arrixaca), Murcia, Spain.

Background: Acute intermittent porphyria (AIP) is a genetic disease characterized by acute neurovisceral attacks. Long-term clinical conditions, chronic symptoms and impaired health related quality of life (HRQoL) have been reported during non-attack periods but mainly in patients with recurrent attacks. Our aim was to investigate these aspects in sporadic AIP (SA-AIP) and latent AIP (L-AIP) patients. Fifty-five participants, 27 SA-AIP (< 4 attacks/year) and 28 L-AIP patients with a prevalent founder mutation from Spain were included. Medical records were reviewed, and individual interviews, physical examinations, biochemical analyses, and abdominal ultrasound scans were conducted. HRQoL was assessed through an EQ-5D-5L questionnaire. A comparative study was made between SA-AIP and L-AIP patients.

Results: The earliest long-term clinical condition associated with SA-AIP was chronic kidney disease. Chronic symptoms were reported in 85.2 % of SA-AIP and 46.4 % of L-AIP patients. Unspecific abdominal pain, fatigue, muscle pain and insomnia were significantly more frequent in SA-AIP than in L-AIP patients. The EQ-5D-5L index was lower in SA-AIP (0.809 vs. 0.926, p = 0.0497), and the impact of "pain", "anxiety-depression" and "mobility" was more intense in the EQ-5D-5L domains in SA-AIP than in L-AIP subjects and the general Spanish population.

Conclusions: AIP remains a chronically symptomatic disease that adversely affects health and quality of life, even in patients with low rate of acute attacks. We suggest a regular monitoring of patients with symptomatic AIP regardless of their attack rate or the time since their last attack, with proper pain management and careful attention to kidney function.
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http://dx.doi.org/10.1186/s13023-021-01742-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7913433PMC
February 2021

[Participant-funded clinical trials on rare diseases].

An Pediatr (Barc) 2020 Oct 1;93(4):267.e1-267.e9. Epub 2020 Jun 1.

CIBER de Enfermedades Raras (CIBERER), ISCIII, Madrid, España; Departamento de Genética y Genómica, Instituto de Investigación Sanitaria, Hospital Universitario Fundación Jiménez Díaz, IIS-UAM, Universidad Autónoma de Madrid, Madrid, España.

The development of medicines for certain rare diseases can be frustrated by lack of funding. In certain cases the patients themselves, or their relatives, occasionally fund the clinical trial in which they will be treated with the investigational medicine. There are 3models of self-funded research: 2of them, "pay to try" and "pay to participate", have already been put into practice. The third, the "plutocratic" proposal, which has been recently put forward is still a theoretical model. In this work the scientific, social and ethical benefits and risks of the 2clinical research models, "pay to participate" and the "plutocratic" proposal, are reviewed. Patient-funded clinical trials are frequently performed through crowdfunding. The most controversial aspects of this funding modality are also addressed in this article from several perspectives. Finally, a future scenario that would allow the launching of self-funded clinical trials in Spain by the "plutocratic" proposal is proposed.
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http://dx.doi.org/10.1016/j.anpedi.2020.03.019DOI Listing
October 2020

Novel CYP4F22 mutations associated with autosomal recessive congenital ichthyosis (ARCI). Study of the CYP4F22 c.1303C>T founder mutation.

PLoS One 2020 18;15(2):e0229025. Epub 2020 Feb 18.

Fundación Pública Galega de Medicina Xenómica-SERGAS, Grupo de Medicina Xenómica-USC, CIBERER, IDIS, Santiago de Compostela, Spain.

Mutations in CYP4F22 cause autosomal recessive congenital ichthyosis (ARCI). However, less than 10% of all ARCI patients carry a mutation in CYP4F22. In order to identify the molecular basis of ARCI among our patients (a cohort of ninety-two Spanish individuals) we performed a mutational analysis using direct Sanger sequencing in combination with a multigene targeted NGS panel. From these, eight ARCI families (three of them with Moroccan origin) were found to carry five different CYP4F22 mutations, of which two were novel. Computational analysis showed that the mutations found were present in highly conserved residues of the protein and may affect its structure and function. Seven of the eight families were carriers of a highly recurrent CYP4F22 variant, c.1303C>T; p.(His435Tyr). A 12Mb haplotype was reconstructed in all c.1303C>T carriers by genotyping ten microsatellite markers flanking the CYP4F22 gene. A prevalent 2.52Mb haplotype was observed among Spanish carrier patients suggesting a recent common ancestor. A smaller core haplotype of 1.2Mb was shared by Spanish and Moroccan families. Different approaches were applied to estimate the time to the most recent common ancestor (TMRCA) of carrier patients with Spanish origin. The age of the mutation was calculated by using DMLE and BDMC2. The algorithms estimated that the c.1303C>T variant arose approximately 2925 to 4925 years ago, while Spanish carrier families derived from a common ancestor who lived in the XIII century. The present study reports five CYP4F22 mutations, two of them novel, increasing the number of CYP4F22 mutations currently listed. Additionally, our results suggest that the recurrent c.1303C>T change has a founder effect in Spanish population and c.1303C>T carrier families originated from a single ancestor with probable African ancestry.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0229025PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7028276PMC
May 2020

EDA, EDAR, EDARADD and WNT10A allelic variants in patients with ectodermal derivative impairment in the Spanish population.

Orphanet J Rare Dis 2019 12 3;14(1):281. Epub 2019 Dec 3.

Departamento de Cirugía, Pediatría, Obstetricia y Ginecología. Facultad de Medicina, Universidad de Murcia, Murcia, Spain.

Background: Ectodermal dysplasias (ED) are a group of genetic conditions affecting the development and/or homeostasis of two or more ectodermal derivatives. An attenuated phenotype is considered a non-syndromic trait when the patient is affected by only one impaired ectodermal structure, such as in non-syndromic tooth agenesis (NSTA) disorder. Hypohidrotic ectodermal dysplasia (HED) is the most highly represented ED. X-linked hypohidrotic ectodermal dysplasia (XLHED) is the most common subtype, with an incidence of 1/50,000-100,000 males, and is associated with the EDA gene (Xq12-q13.1); the dominant and recessive subtypes involve the EDAR (2q13) and EDARADD (1q42.3) genes, respectively. The WNT10A gene (2q35) is associated more frequently with NSTA. Our goal was to determine the mutational spectrum in a cohort of 72 Spanish patients affected by one or more ectodermal derivative impairments referred to as HED (63/72) or NSTA (9 /72) to establish the prevalence of the allelic variants of the four most frequently associated genes. Sanger sequencing of the EDA, EDAR, EDARADD and WNT10A genes and multiplex ligation-dependent probe amplification (MLPA) were performed.

Results: A total of 61 children and 11 adults, comprising 50 males and 22 females, were included. The average ages were 5.4 and 40.2 years for children and adults, respectively. A molecular basis was identified in 51/72 patients, including 47/63 HED patients, for whom EDA was the most frequently involved gene, and 4/9 NSTA patients, most of whom had variants of WNT10A. Among all the patients, 37/51 had variants of EDA, 8/51 had variants of the WNT10A gene, 4/51 had variants of EDAR and 5/51 had variants of EDARADD. In 42/51 of cases, the variants were inherited according to an X-linked pattern (27/42), with the remaining showing an autosomal dominant (10/42) or autosomal recessive (5/42) pattern. Among the NSTA patients, 3/9 carried pathogenic variants of WNT10A and 1/9 carried EDA variants. A total of 60 variants were detected in 51 patients, 46 of which were different, and out of these 46 variants, 12 were novel.

Conclusions: This is the only molecular study conducted to date in the Spanish population affected by ED. The EDA, EDAR, EDARADD and WNT10A genes constitute the molecular basis in 70.8% of patients with a 74.6% yield in HED and 44.4% in NSTA. Twelve novel variants were identified. The WNT10A gene has been confirmed as the second molecular candidate that has been identified and accounts for one-half of non-EDA patients and one-third of NSTA patients. Further studies using next generation sequencing (NGS) will help to identify other contributory genes in the remaining uncharacterized Spanish patients.
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http://dx.doi.org/10.1186/s13023-019-1251-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6892193PMC
December 2019

Heterozygous pathogenic variants in GLI1 are a common finding in isolated postaxial polydactyly A/B.

Hum Mutat 2020 01 6;41(1):265-276. Epub 2019 Nov 6.

Instituto de Investigaciones Biomédicas "Alberto Sols", CSIC-UAM, Madrid, Spain.

Postaxial polydactyly (PAP) is a frequent limb malformation consisting in the duplication of the fifth digit of the hand or foot. Morphologically, this condition is divided into type A and B, with PAP-B corresponding to a more rudimentary extra-digit. Recently, biallelic truncating variants in the transcription factor GLI1 were reported to be associated with a recessive disorder, which in addition to PAP-A, may include syndromic features. Moreover, two heterozygous subjects carrying only one inactive copy of GLI1 were also identified with PAP. Herein, we aimed to determine the level of involvement of GLI1 in isolated PAP, a condition previously established to be autosomal dominantly inherited with incomplete penetrance. We analyzed the coding region of GLI1 in 95 independent probands with nonsyndromic PAP and found 11.57% of these subjects with single heterozygous pathogenic variants in this gene. The detected variants lead to premature termination codons or result in amino acid changes in the DNA-binding domain of GLI1 that diminish its transactivation activity. Family segregation analysis of these variants was consistent with dominant inheritance with incomplete penetrance. We conclude that heterozygous changes in GLI1 underlie a significant proportion of sporadic or familial cases of isolated PAP-A/B.
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http://dx.doi.org/10.1002/humu.23921DOI Listing
January 2020

[Assessment of psychomotor development of Spanish children up to 3 years of age conceived by assisted reproductive techniques: Prospective matched cohort study].

An Pediatr (Barc) 2020 Apr 2;92(4):200-207. Epub 2019 Sep 2.

Genética Médica, Servicio de Pediatría, Hospital Clínico Universitario Virgen de la Arrixaca (HCUVA), Instituto Murciano de Investigación Biosanitaria (IMIB)-Arrixaca, Murcia, España; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, España.

Introduction: More than five million children have been conceived by assisted reproductive techniques (ART) around the world. Most authors agree that there are no differences in psychomotor development in comparison to naturally conceived children. However, these results are still contradictory.

Objective: To determine whether children born from a cohort of ART-clinical gestations have a higher risk of suffering neurodevelopmental disorders in comparison to a control group. The potential associated ART-factors associated were also determined.

Material And Methods: The study included the assessment of children up to 3 years old conceived by ART, and born from a cohort of women treated by the reproduction unit of a public hospital from May 2012 to May 2014. A simultaneous assessment was made of matched controls, by following the newborn naturally conceived after the ART-case, of the same group of maternal age, gestational age, and type of gestation.

Results: There were 243 clinical gestations and 267 ART-newborns, of which 231 were assessed (87%). A simultaneous assessment was carried out in 208/230 controls (90%). There were no differences in neurodevelopmental disorders (global developmental delay, autism spectrum or language delay). Multivariate analysis of potential ART factors only showed an association between transfer of frozen embryos with language delay that has not been previously described.

Conclusions: There were no differences between groups after adjusting the results according to maternal age, multiple pregnancy, and other possible confounding factors, supporting that the role of these factors may be more relevant than the ART itself. The association between frozen embryo transfer and language delay has not been previously described. Thus, more studies are needed to confirm or refute this relationship.
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http://dx.doi.org/10.1016/j.anpedi.2019.07.006DOI Listing
April 2020

[First Spanish case of syndromic intellectual disability with dysmorphic facies, seizures, and distal limb anomalies caused by balletic mutations in the OTUD6B gene].

An Pediatr (Barc) 2020 Mar 27;92(3):169-171. Epub 2019 May 27.

Sección de Genética Médica, Servicio de Pediatría, Hospital Clínico Universitario Virgen de la Arrixaca (HCUVA), IMIB-Arrixaca, El Palmar, Murcia, España; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Madrid, España.

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http://dx.doi.org/10.1016/j.anpedi.2019.03.010DOI Listing
March 2020

High penetrance of acute intermittent porphyria in a Spanish founder mutation population and CYP2D6 genotype as a susceptibility factor.

Orphanet J Rare Dis 2019 02 26;14(1):59. Epub 2019 Feb 26.

CIBERER-ISCIII, Madrid, Spain.

Background: Acute intermittent porphyria (AIP) is a low-penetrant genetic metabolic disease caused by a deficiency of hydroxymethylbilane synthase (HMBS) in the haem biosynthesis. Manifest AIP (MAIP) is considered when carriers develop typical acute neurovisceral attacks with elevation of porphyrin precursors, while the absence of attacks is referred to as latent AIP (LAIP). Attacks are often triggered by drugs, endocrine factors, fasting or stress. Although AIP penetrance is traditionally considered to be around 10-20%, it has been estimated to be below 1% in general population studies and a higher figure has been found in specific AIP populations. Genetic susceptibility factors underlying penetrance are still unknown. Drug-metabolizing cytochrome P450 enzymes (CYP) are polymorphic haem-dependent proteins which play a role in haem demand, so they might modulate the occurrence of AIP attacks. Our aim was to determine the prevalence and penetrance of AIP in our population and analyse the main hepatic CYP genes to assess their association with acute attacks. For this, CYP2C9*2, *3; CYP2C19*2; CYP2D6*4, *5; CYP3A4*1B and CYP3A5*3 defective alleles were genotyped in fifty AIP carriers from the Region of Murcia, a Spanish population with a high frequency of the HMBS founder mutation c.669_698del30.

Results: AIP penetrance was 52%, and prevalence was estimated as 17.7 cases/million inhabitants. The frequency of defective CYP2D6 alleles was 3.5 times higher in LAIP than in MAIP. MAIP was less frequent among CYP2D6*4 and *5 carriers (p < 0.05). The urine porphobilinogen (PBG)-to-creatinine ratio was lower in these individuals, although it was associated with a lower prevalence of attacks (p < 0.05) rather than with the CYP2D6 genotype.

Conclusions: AIP prevalence in our region is almost 3 times higher than that estimated for the rest of Spain. The penetrance was high, and similar to other founder mutation AIP populations. This is very relevant for genetic counselling and effective health care. CYP2D6*4 and *5 alleles may be protective factors for acute attacks, and CYP2D6 may constitute a penetrance-modifying gene. Further studies are needed to confirm these findings, which would allow a further progress in clinical risk profile assessment based on the CYP genotype, leading to predictive personalized medicine for each AIP carrier in the future.
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http://dx.doi.org/10.1186/s13023-019-1031-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390611PMC
February 2019

Elosulfase alfa for mucopolysaccharidosis type IVA: Real-world experience in 7 patients from the Spanish Morquio-A early access program.

Mol Genet Metab Rep 2018 Jun 5;15:116-120. Epub 2018 Apr 5.

Pediatric Neurology Unit, Hospital Universitari Vall d'Hebron, Barcelona, Spain.

There is a growing interest in evaluating the effectiveness of enzyme replacement therapy (ERT) with elosulfase alfa in patients with mucopolysaccharidosis type IVA (MPS-IVA) under real-world conditions. We present the experience of seven pediatric MPS-IVA patients from the Spanish Morquio-A Early Access Program. Efficacy was evaluated based on the distance walked in the 6-min walking test (6-MWT) and the 3-min-stair-climb-test (3-MSCT) at baseline and after 8 months of ERT treatment. Additionally, urinary glycosaminoglycans were measured, and a molecular analysis of a GALNS mutation was performed. The health-related quality of life was evaluated using the EuroQoL (EQ)-5D-5 L. The distance walked according to the 6-MWT ranged from 0 to 325 m at baseline and increased to 12-300 m after 8 months with elosulfase alfa (the walked distance improved in all patients except one). An increase was observed for the two patients who had to use a wheelchair. Improvements were also observed for the 3-MSCT in four patients, whereas two patients showed no changes. Three patients showed an improvement in the EQ-VAS score, whereas the scores of three patients remained stable. Regarding urinary glycosaminoglycans measurements, an irregular response was observed. Our results showed overall improvement in endurance and functionality after 8 months of elosulfase alfa treatment in a heterogeneous subset of MPS IVA patients with severe clinical manifestations managed in a real-world setting.
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http://dx.doi.org/10.1016/j.ymgmr.2018.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6047108PMC
June 2018

Comprehensive long-term efficacy and safety of recombinant human alpha-mannosidase (velmanase alfa) treatment in patients with alpha-mannosidosis.

J Inherit Metab Dis 2018 11 3;41(6):1225-1233. Epub 2018 May 3.

Centre de Référence des Maladies Héréditaires du Métabolisme, Hôpital Femme Mère Enfant, Lyon, France.

Introduction: Long-term outcome data provide important insights into the clinical utility of enzyme replacement therapies. Such data are presented for velmanase alfa in the treatment of alpha-mannosidosis (AM).

Methods: Patient data (n = 33; 14 adults, 19 paediatric) from the clinical development programme for velmanase alfa were integrated in this prospectively-designed analysis of long-term efficacy and safety. Patients who participated in the phase I/II or phase III trials and were continuing to receive treatment after completion of the trials were invited to participate in a comprehensive evaluation visit to assess long-term outcomes. Primary endpoints were changes in serum oligosaccharide and the 3-minute stair climb test (3MSCT).

Results: Mean (SD) treatment exposure was 29.3 (15.2) months. Serum oligosaccharide levels were significantly reduced in the overall population at 12 months (mean change: -72.7%, P < 0.001) and remained statistically significant at last observation (-62.8%, P < 0.001). A mean improvement of +9.3% in 3MSCT was observed at 12 months (P = 0.013), which also remained statistically significant at last observation (+13.8%, P = 0.004), with a more pronounced improvement detected in the paediatric subgroup. No treatment-emergent adverse events were reported leading to permanent treatment discontinuation.

Conclusions: Patients treated with velmanase alfa experienced improvements in biochemical and functional measures that were maintained for up to 4 years. Long term follow-up is important and further supports the use of velmanase alfa as an effective and well-tolerated treatment for AM. Based on the currently available data set, no baseline characteristic can be predictive of treatment outcome. Early treatment during paediatric age showed better outcome in functional endpoints.
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http://dx.doi.org/10.1007/s10545-018-0175-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6326957PMC
November 2018

Genetic predisposition to fetal alcohol syndrome: association with congenital disorders of N-glycosylation.

Pediatr Res 2018 01 20;83(1-1):119-127. Epub 2017 Sep 20.

Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Centro Regional de Hemodonación, Universidad de Murcia, IMIB-Arrixaca, CIBERER, Murcia, Spain.

BackgroundFetal alcohol syndrome (FAS) is caused by maternal alcohol consumption during pregnancy; although additional factors might be involved, as development and severity are not directly related to alcohol intake. The abnormal glycosylation caused by alcohol might play a role in FAS according to the clinical similarities shared with congenital disorders of glycosylation (CDG). Thus, mutations underlying CDG, affecting genes involved in glycosylation, could also be involved in FAS.MethodsA panel of 74 genes involved in N-glycosylation was sequenced in 25 FAS patients and 20 controls with prenatal alcohol exposure. Transferrin glycoforms were evaluated by HPLC.ResultsRare (minor allele frequency<0.009) missense/splice site variants were more frequent in FAS than controls (84% vs. 50%; P=0.034, odds ratio: 5.25, 95% confidence interval: 1.3-20.9). Remarkably, three patients, but no controls, carried variants with functional effects identified in CDG patients. Moreover, the patient with the most severe clinical phenotype was the only one carrying two variants with functional effects. Family studies support that the combination of a genetic defect and alcohol consumption during pregnancy might have a role in FAS development.ConclusionsOur study supports that the rare variants of genes involved in N-glycosylation could play a role in the development and severity of FAS under prenatal alcohol exposure.
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http://dx.doi.org/10.1038/pr.2017.201DOI Listing
January 2018

Molecular spectrum and differential diagnosis in patients referred with sporadic or autosomal recessive osteogenesis imperfecta.

Mol Genet Genomic Med 2017 Jan 20;5(1):28-39. Epub 2016 Dec 20.

Instituto de Investigaciones BiomédicasConsejo Superior de Investigaciones Científicas-Universidad Autónoma de MadridMadridSpain; CIBER de enfermedades Raras (CIBERER)MadridSpain; Skeletal Dysplasia Multidisciplinary Unit (UMDE)Hospital Universitario La PazMadridSpain.

Background: Osteogenesis imperfecta (OI) is a heterogeneous bone disorder characterized by recurrent fractures. Although most cases of OI have heterozygous mutations in or and show autosomal dominant inheritance, during the last years there has been an explosion in the number of genes responsible for both recessive and dominant forms of this condition. Herein, we have analyzed a cohort of patients with OI, all offspring of unaffected parents, to determine the spectrum of variants accounting for these cases. Twenty patients had nonrelated parents and were sporadic, and 21 were born to consanguineous relationships.

Methods: Mutation analysis was performed using a next-generation sequencing gene panel, homozygosity mapping, and whole exome sequencing (WES).

Results: Patients offspring of nonconsanguineous parents were mostly identified with or heterozygous changes, although there were also a few cases with and heterozygous mutations. Only one sporadic patient was a compound heterozygote for two recessive mutations. Patients offspring of consanguineous parents showed homozygous changes in a variety of genes including ,,,,,,, and . In addition, two patients born to consanguineous parents were found to have de novo heterozygous mutations demonstrating that causative variants in the collagen I structural genes cannot be overlooked in affected children from consanguineous couples. Further to this, WES analysis in probands lacking mutations in OI genes revealed deleterious variants in ,, and , which are associated with congenital indifference to pain (CIP) and Fanconi-Bickel syndrome (FBS).

Conclusion: This work provides useful information for clinical and genetic diagnosis of OI patients with no positive family history of this disease. Our data also indicate that CIP and FBS are conditions to be considered in the differential diagnosis of OI and suggest a positive role of and in bone development.
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http://dx.doi.org/10.1002/mgg3.257DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5241205PMC
January 2017

Small 6q16.1 Deletions Encompassing POU3F2 Cause Susceptibility to Obesity and Variable Developmental Delay with Intellectual Disability.

Am J Hum Genet 2016 Feb 28;98(2):363-72. Epub 2016 Jan 28.

Manchester Centre for Genomic Medicine, Institute of Human Development, Faculty of Medical and Human Sciences, University of Manchester, Manchester M13 9WL, UK; Manchester Centre for Genomic Medicine, St Mary's Hospital, Central Manchester University Hospitals NHS Foundation Trust, Manchester Academic Health Science Centre (MAHSC), Manchester M13 9WL, UK. Electronic address:

Genetic studies of intellectual disability and identification of monogenic causes of obesity in humans have made immense contribution toward the understanding of the brain and control of body mass. The leptin > melanocortin > SIM1 pathway is dysregulated in multiple monogenic human obesity syndromes but its downstream targets are still unknown. In ten individuals from six families, with overlapping 6q16.1 deletions, we describe a disorder of variable developmental delay, intellectual disability, and susceptibility to obesity and hyperphagia. The 6q16.1 deletions segregated with the phenotype in multiplex families and were shown to be de novo in four families, and there was dramatic phenotypic overlap among affected individuals who were independently ascertained without bias from clinical features. Analysis of the deletions revealed a ∼350 kb critical region on chromosome 6q16.1 that encompasses a gene for proneuronal transcription factor POU3F2, which is important for hypothalamic development and function. Using morpholino and mutant zebrafish models, we show that POU3F2 lies downstream of SIM1 and controls oxytocin expression in the hypothalamic neuroendocrine preoptic area. We show that this finding is consistent with the expression patterns of POU3F2 and related genes in the human brain. Our work helps to further delineate the neuro-endocrine control of energy balance/body mass and demonstrates that this molecular pathway is conserved across multiple species.
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http://dx.doi.org/10.1016/j.ajhg.2015.12.014DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4746363PMC
February 2016

Lack of IL7Rα expression in T cells is a hallmark of T-cell immunodeficiency in Schimke immuno-osseous dysplasia (SIOD).

Clin Immunol 2015 Dec 21;161(2):355-65. Epub 2015 Oct 21.

Pediatric Multidisciplinary Unit, AP-HM Timone Enfant, Aix-Marseille University, Marseille, France.

Schimke immuno-osseous dysplasia (SIOD) is an autosomal recessive, fatal childhood disorder associated with skeletal dysplasia, renal dysfunction, and T-cell immunodeficiency. This disease is linked to biallelic loss-of-function mutations of the SMARCAL1 gene. Although recurrent infection, due to T-cell deficiency, is a leading cause of morbidity and mortality, the etiology of the T-cell immunodeficiency is unclear. Here, we demonstrate that the T cells of SIOD patients have undetectable levels of protein and mRNA for the IL-7 receptor alpha chain (IL7Rα) and are unresponsive to stimulation with IL-7, indicating a loss of functional receptor. No pathogenic mutations were detected in the exons of IL7R in these patients; however, CpG sites in the IL7R promoter were hypermethylated in SIOD T cells. We propose therefore that the lack of IL7Rα expression, associated with hypermethylation of the IL7R promoter, in T cells and possibly their earlier progenitors, restricts T-cell development in SIOD patients.
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http://dx.doi.org/10.1016/j.clim.2015.10.005DOI Listing
December 2015

Two novel POC1A mutations in the primordial dwarfism, SOFT syndrome: Clinical homogeneity but also unreported malformations.

Am J Med Genet A 2016 Jan 16;170A(1):210-6. Epub 2015 Sep 16.

Institute of Medical & Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain.

Primordial dwarfism encompasses rare conditions characterized by severe intrauterine growth retardation and growth deficiency throughout life. Recently, three POC1A mutations have been reported in six families with the primordial dwarfism, SOFT syndrome (Short stature, Onychodysplasia, Facial dysmorphism, and hypoTrichosis). Using a custom-designed Next-generation sequencing skeletal dysplasia panel, we have identified two novel homozygous POC1A mutations in two individuals with primordial dwarfism. The severe growth retardation and the facial profiles are strikingly similar between our patients and those described previously. However, one of our patients was diagnosed with severe foramen magnum stenosis and subglottic tracheal stenosis, malformations not previously associated with this syndrome. Our findings confirm that POC1A mutations cause SOFT syndrome and that mutations in this gene should be considered in patients with severe pre- and postnatal short stature, symmetric shortening of long bones, triangular facies, sparse hair and short, thickened distal phalanges.
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http://dx.doi.org/10.1002/ajmg.a.37393DOI Listing
January 2016

Larger aggregates of mutant seipin in Celia's Encephalopathy, a new protein misfolding neurodegenerative disease.

Neurobiol Dis 2015 Nov 15;83:44-53. Epub 2015 Aug 15.

CIMUS Biomedical Research Institute, University of Santiago de Compostela-IDIS, 15782 Santiago de Compostela, Spain; Department of Medicine, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain. Electronic address:

Celia's Encephalopathy (MIM #615924) is a recently discovered fatal neurodegenerative syndrome associated with a new BSCL2 mutation (c.985C>T) that results in an aberrant isoform of seipin (Celia seipin). This mutation is lethal in both homozygosity and compounded heterozygosity with a lipodystrophic BSCL2 mutation, resulting in a progressive encephalopathy with fatal outcomes at ages 6-8. Strikingly, heterozygous carriers are asymptomatic, conflicting with the gain of toxic function attributed to this mutation. Here we report new key insights about the molecular pathogenic mechanism of this new syndrome. Intranuclear inclusions containing mutant seipin were found in brain tissue from a homozygous patient suggesting a pathogenic mechanism similar to other neurodegenerative diseases featuring brain accumulation of aggregated, misfolded proteins. Sucrose gradient distribution showed that mutant seipin forms much larger aggregates as compared with wild type (wt) seipin, indicating an impaired oligomerization. On the other hand, the interaction between wt and Celia seipin confirmed by coimmunoprecipitation (CoIP) assays, together with the identification of mixed oligomers in sucrose gradient fractionation experiments can explain the lack of symptoms in heterozygous carriers. We propose that the increased aggregation and subsequent impaired oligomerization of Celia seipin leads to cell death. In heterozygous carriers, wt seipin might prevent the damage caused by mutant seipin through its sequestration into harmless mixed oligomers.
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http://dx.doi.org/10.1016/j.nbd.2015.08.006DOI Listing
November 2015

Exome sequencing unravels unexpected differential diagnoses in individuals with the tentative diagnosis of Coffin-Siris and Nicolaides-Baraitser syndromes.

Hum Genet 2015 Jun 28;134(6):553-68. Epub 2015 Feb 28.

Institut für Humangenetik, Universitätsklinikum Essen, Universität Duisburg-Essen, Hufelandstr. 55, 45122, Essen, Germany,

Coffin-Siris syndrome (CSS) and Nicolaides-Baraitser syndrome (NCBRS) are rare intellectual disability/congenital malformation syndromes that represent distinct entities but show considerable clinical overlap. They are caused by mutations in genes encoding members of the BRG1- and BRM-associated factor (BAF) complex. However, there are a number of patients with the clinical diagnosis of CSS or NCBRS in whom the causative mutation has not been identified. In this study, we performed trio-based whole-exome sequencing (WES) in ten previously described but unsolved individuals with the tentative diagnosis of CSS or NCBRS and found causative mutations in nine out of ten individuals. Interestingly, our WES analysis disclosed overlapping differential diagnoses including Wiedemann-Steiner, Kabuki, and Adams-Oliver syndromes. In addition, most likely causative de novo mutations were identified in GRIN2A and SHANK3. Moreover, trio-based WES detected SMARCA2 and SMARCA4 deletions, which had not been annotated in a previous Haloplex target enrichment and next-generation sequencing of known CSS/NCBRS genes emphasizing the advantages of WES as a diagnostic tool. In summary, we discuss the phenotypic and diagnostic challenges in clinical genetics, establish important differential diagnoses, and emphasize the cardinal features and the broad clinical spectrum of BAF complex disorders and other disorders caused by mutations in epigenetic landscapers.
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http://dx.doi.org/10.1007/s00439-015-1535-8DOI Listing
June 2015

Identification of the fourth duplication of upstream IHH regulatory elements, in a family with craniosynostosis Philadelphia type, helps to define the phenotypic characterization of these regulatory elements.

Am J Med Genet A 2015 Apr 18;167A(4):902-6. Epub 2015 Feb 18.

Institute of Medical and Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain; Centro de Investigación Biomédica en Enfermedades Raras (CIBERER), Instituto Carlos, Madrid, Spain.

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http://dx.doi.org/10.1002/ajmg.a.36811DOI Listing
April 2015

Clinical comparison of 10q26 overlapping deletions: delineating the critical region for urogenital anomalies.

Am J Med Genet A 2015 Apr 5;167A(4):786-90. Epub 2015 Feb 5.

Sección de Citogenética, Centro de Bioquímica y Genética Clínica, Hospital Clínico Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain; Instituto Murciano de Investigación Biosanitaria-Arrixaca (IMIB-Arrixaca); Centro de Investigación Biomédica de Red de Enfermedades Raras (CIBERER), Instituto de, Salud Carlos III (ISCIII), Madrid, Spain.

The 10q26 deletion syndrome is a clinically heterogeneous disorder. The most common phenotypic characteristics include pre- and/or postnatal growth retardation, microcephaly, developmental delay/intellectual disability and a facial appearance consisting of a broad nasal bridge with a prominent nose, low-set malformed ears, strabismus, and a thin vermilion of the upper lip. In addition, limb and cardiac anomalies as well as urogenital anomalies are occasionally observed. In this report, we describe three unrelated females with 10q26 terminal deletions who shared clinical features of the syndrome, including urogenital defects. Cytogenetic studies showed an apparently de novo isolated deletion of the long arm of chromosome 10, with breakpoints in 10q26.1, and subsequent oligo array-CGH analysis confirmed the terminal location and defined the size of the overlapping deletions as ∼ 13.46, ∼ 9.31 and ∼ 9.17 Mb. We compared the phenotypic characteristics of the present patients with others reported to have isolated deletions and we suggest that small 10q26.2 terminal deletions may be associated with growth retardation, developmental delay/intellectual disability, craniofacial features and external genital anomalies whereas longer terminal deletions affecting the 10q26.12 and/or 10q26.13 regions may be responsible for renal/urinary tract anomalies. We propose that the haploinsufficiency of one or several genes located in the 10q26.12-q26.13 region may contribute to the renal or urinary tract pathogenesis and we highlight the importance of FGFR2 and probably of CTBP2 as candidate genes.
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http://dx.doi.org/10.1002/ajmg.a.36949DOI Listing
April 2015

Recombinant human leptin treatment in genetic lipodystrophic syndromes: the long-term Spanish experience.

Endocrine 2015 May 4;49(1):139-47. Epub 2014 Nov 4.

Division of Endocrinology and Nutrition, University Clinical Hospital of Santiago de Compostela, Santiago de Compostela, Spain,

Lipodystrophies are a group of diseases mainly characterized by a loss of adipose tissue and frequently associated with insulin resistance, hypertriglyceridemia, and hepatic steatosis. In uncommon lipodystrophies, these complications frequently are difficult to control with conventional therapeutic approaches. This retrospective study addressed the effectiveness of recombinant methionyl leptin (metreleptin) for improving glucose metabolism, lipid profile, and hepatic steatosis in patients with genetic lipodystrophic syndromes. We studied nine patients (five females and four males) with genetic lipodystrophies [seven with Berardinelli-Seip syndrome, one with atypical progeroid syndrome, and one with type 2 familial partial lipodystrophy (FPLD)]. Six patients were children under age 9 years, and all patients had baseline triglycerides levels >2.26 mmol/L and hepatic steatosis; six had poorly controlled diabetes mellitus. Metreleptin was self-administered subcutaneously daily at a final dose that ranged between 0.05 and 0.24 mg/(kg day) [median: 0.08 mg/(kg day)] according to the body weight. The duration of treatment ranged from 9 months to 5 years, 9 months (median: 3 years). Plasma glucose, hemoglobin A1c (Hb A1c), lipid profile, plasma insulin and leptin, and hepatic enzymes were evaluated at baseline and at least every 6 months. Except for the patient with FPLD, metreleptin replacement significantly improved metabolic control (Hb A1c: from 10.4 to 7.1 %, p < 0.05). Plasma triglycerides were reduced 76 % on average, and hepatic enzymes decreased more than 65 %. This study extends knowledge about metreleptin replacement in genetic lipodystrophies, bearing out its effectiveness for long periods of time.
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http://dx.doi.org/10.1007/s12020-014-0450-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4412649PMC
May 2015

Expanding the mutation spectrum in 182 Spanish probands with craniosynostosis: identification and characterization of novel TCF12 variants.

Eur J Hum Genet 2015 Jul 1;23(7):907-14. Epub 2014 Oct 1.

1] Institute of Medical and Molecular Genetics (INGEMM), Hospital Universitario La Paz, Universidad Autónoma de Madrid, IdiPAZ, Madrid, Spain [2] Centro de Investigación Biomédica en Enfermedades Raras (CIBERER), Instituto Carlos III, Madrid, Spain.

Craniosynostosis, caused by the premature fusion of one or more of the cranial sutures, can be classified into non-syndromic or syndromic and by which sutures are affected. Clinical assignment is a difficult challenge due to the high phenotypic variability observed between syndromes. During routine diagnostics, we screened 182 Spanish craniosynostosis probands, implementing a four-tiered cascade screening of FGFR2, FGFR3, FGFR1, TWIST1 and EFNB1. A total of 43 variants, eight novel, were identified in 113 (62%) patients: 104 (92%) detected in level 1; eight (7%) in level 2 and one (1%) in level 3. We subsequently screened additional genes in the probands with no detected mutation: one duplication of the IHH regulatory region was identified in a patient with craniosynostosis Philadelphia type and five variants, four novel, were identified in the recently described TCF12, in probands with coronal or multisuture affectation. In the 19 Saethre-Chotzen syndrome (SCS) individuals in whom a variant was detected, 15 (79%) carried a TWIST1 variant, whereas four (21%) had a TCF12 variant. Thus, we propose that TCF12 screening should be included for TWIST1 negative SCS patients and in patients where the coronal suture is affected. In summary, a molecular diagnosis was obtained in a total of 119/182 patients (65%), allowing the correct craniosynostosis syndrome classification, aiding genetic counselling and in some cases provided a better planning on how and when surgical intervention should take place and, subsequently the appropriate clinical follow up.
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http://dx.doi.org/10.1038/ejhg.2014.205DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4463497PMC
July 2015

A new overgrowth syndrome is due to mutations in RNF125.

Hum Mutat 2014 Dec;35(12):1436-41

CIBERER, Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Madrid, Spain; Molecular Endocrinology Unit - Overgrowth Syndromes Laboratory, INGEMM, Instituto de Genética Médica y Molecular, IdiPAZ, Hospital Universitario La Paz, Universidad Autónoma de Madrid (UAM), Madrid, Spain.

Overgrowth syndromes (OGS) are a group of disorders in which all parameters of growth and physical development are above the mean for age and sex. We evaluated a series of 270 families from the Spanish Overgrowth Syndrome Registry with no known OGS. We identified one de novo deletion and three missense mutations in RNF125 in six patients from four families with overgrowth, macrocephaly, intellectual disability, mild hydrocephaly, hypoglycemia, and inflammatory diseases resembling Sjögren syndrome. RNF125 encodes an E3 ubiquitin ligase and is a novel gene of OGS. Our studies of the RNF125 pathway point to upregulation of RIG-I-IPS1-MDA5 and/or disruption of the PI3K-AKT and interferon signaling pathways as the putative final effectors.
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http://dx.doi.org/10.1002/humu.22689DOI Listing
December 2014

[Cardiofaciocutaneous syndrome, a Noonan syndrome related disorder: clinical and molecular findings in 11 patients].

Med Clin (Barc) 2015 Jan 4;144(2):67-72. Epub 2014 Sep 4.

Centro de Investigación Biomédica en Red en enfermedades raras (CIBERER); Laboratorio Diagnóstico Molecular, Servicio de Bioquímica, Instituto de Investigación Sanitaria Gregorio Marañón (IiSGM), Madrid, España.

Objectives: To describe 11 patients with cardiofaciocutaneous syndrome (CFC) and compare them with 130 patients with other RAS-MAPK syndromes (111 Noonan syndrome patients [NS] and 19 patients with LEOPARD syndrome).

Patients And Methods: Clinical data from patients submitted for genetic analysis were collected. Bidirectional sequencing analysis of PTPN11, SOS1, RAF1, BRAF, and MAP2K1 focused on exons carrying recurrent mutations, and of all KRAS exons were performed.

Results: Six different mutations in BRAF were identified in 9 patients, as well as 2 MAP2K1 mutations. Short stature, developmental delay, language difficulties and ectodermal anomalies were more frequent in CFC patients when compared with other neuro-cardio-faciocutaneous syndromes (P<.05). In at least 2 cases molecular testing helped reconsider the diagnosis.

Discussion: CFC patients showed a rather severe phenotype but at least one patient with BRAF mutation showed no developmental delay, which illustrates the variability of the phenotypic spectrum caused by BRAF mutations. Molecular genetic testing is a valuable tool for differential diagnosis of CFC and NS related disorders.
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http://dx.doi.org/10.1016/j.medcli.2014.06.009DOI Listing
January 2015

LEOPARD syndrome: a variant of Noonan syndrome strongly associated with hypertrophic cardiomyopathy.

Rev Esp Cardiol (Engl Ed) 2013 May 11;66(5):350-6. Epub 2013 Jan 11.

Laboratorio de Genética Molecular, Hospital General Universitario Gregorio Marañón, Instituto de Investigación Sanitaria Gregorio Marañón, Madrid, Spain.

Introduction And Objectives: LEOPARD syndrome is an autosomal dominant condition related to Noonan syndrome, although it occurs less frequently. The aim of this study was to characterize the clinical and molecular features of a large series of LEOPARD syndrome patients.

Methods: We collected clinical data from 19 patients in 10 hospitals. Bidirectional sequencing analysis of PTPN11, RAF1, and BRAF focused on exons carrying recurrent mutations.

Results: After facial dysmorphism, structural heart defects (88%) were the most common feature described. Hypertrophic cardiomyopathy (71%) was diagnosed more often than pulmonary valve stenosis (35%). Multiple lentigines or café au lait spots were found in 84% of the series, and deafness was diagnosed in 3 patients. Mutations in PTPN11 were identified in 16 (84%) patients (10 patients had the recurrent LEOPARD syndrome mutation, p.Thr468Met) (NP_002825.3T468M). Two other patients had a mutation in RAF, and 1 patient had a mutation in BRAF. When compared with other neurocardiofaciocutaneous syndromes, LEOPARD syndrome patients showed a higher prevalence of hypertrophic cardiomyopathy and cutaneous abnormalities, and a lower prevalence of pulmonary valve stenosis and short stature.

Conclusions: LEOPARD syndrome patients display distinctive features apart from multiple lentigines, such as a higher prevalence of hypertrophic cardiomyopathy and lower prevalence of short stature. Given its clinical implications, active search for hypertrophic cardiomyopathy is warranted in Noonan syndrome spectrum patients, especially in LEOPARD syndrome patients.
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http://dx.doi.org/10.1016/j.rec.2012.09.015DOI Listing
May 2013

Comprehensive clinical evaluation of a large Spanish family with Anderson-Fabry disease, novel GLA mutation and severe cardiac phenotype.

Med Clin (Barc) 2014 Jun 26;142(11):497-504. Epub 2014 Mar 26.

Servicio de Cardiología, Hospital Clínico Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain; Facultad de Medicina, Universidad de Murcia, Spain.

Background And Objective: Fabry disease is an X-linked multisystemic lysosomal-storage condition. We describe a large family with a novel GLA mutation: p.M187R/g7219 T>G.

Patients And Methods: Anamnesis/physical-exam, blood/urine analysis, α-Gal-A activity and/or genetic study of at-risk individuals and multidisciplinary evaluation in confirmed cases.

Results: 4 males and 13 heterozygous-females displayed the mutation. Cardiac/renal/neurological disease was diagnosed at a mean age of 41/29/39 years in males and 51/56/46 years in females. Onset mean age was 20 years versus 42 years. 9/15 had cardiomyopathy. Delta wave suggestive of accessory pathway was identified in 1 male and 2 females. 1 female had cardiac arrest (ventricular fibrillation, 61 years). 2 females and 1 male died suddenly (63, 64 and 57 years). Cardiac-subscore of Mainz Severity-Score-Index was severe for males and females over 40 years. 4/15(26%) developed early renal disease. 2 males needed dialysis. 1 male died at 69 years in spite of kidney-heart transplant.

Conclusion: We describe the largest genetically confirmed Spanish family using multidisciplinary evaluation and MSSI calculation. The novel mutation p.M187R/g7219 T>G is associated with a particularly malignant cardiac phenotype in males and females over 40 years. Severity was higher than that of the largest Spanish FOS-cohort. Short-PR with delta is being reported for the first time.
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http://dx.doi.org/10.1016/j.medcli.2014.01.032DOI Listing
June 2014

Array CGH detection of a novel cryptic deletion at 3q13 in a complex chromosome rearrangement.

Genomics 2014 Apr 4;103(4):288-91. Epub 2014 Mar 4.

Unidad de Genética Médica, Servicio de Pediatría, Hospital Clínico Universitario "Virgen de la Arrixaca", El Palmar, Murcia, Spain; Centro de Investigación Biomédica de Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain; Cátedra de Genética Médica, Universidad Católica de San Antonio (UCAM), Murcia, Spain.

Complex chromosome rearrangements (CCRs) are extremely rare in humans. About 20% of the apparently balanced CCRs have an abnormal phenotype and the degree of severity correlates with a higher number of breakpoints. Several studies using FISH and microarray technologies have shown that deletions in the breakpoints are common although duplications, insertions and inversions have also been detected. We report a patient with two simultaneous reciprocal translocations, t(3;4) and t(2;14;18), involving five chromosomes and six breakpoints. He showed dysmorphic features, preaxial polydactyly in the left hand, brachydactyly, postnatal growth retardation and developmental delay. The rearrangement was characterized by FISH analysis which detected an interstitial segment from chromosome 14 inserted in the derivative chromosome 2, and by whole genome array which revealed an interstitial deletion of approximately 4.5 Mb at the breakpoint site on chromosome 3. To our knowledge this microdeletion has not been previously reported and includes ~12 genes. The haploinsufficiency of one or several of these genes is likely to have contributed to the clinical phenotype of the patient.
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http://dx.doi.org/10.1016/j.ygeno.2014.02.008DOI Listing
April 2014

Two mutations in IFITM5 causing distinct forms of osteogenesis imperfecta.

Am J Med Genet A 2014 May 29;164A(5):1136-42. Epub 2014 Jan 29.

Unidad de Genética Médica, Servicio de Pediatría, Hospital Clínico Universitario Virgen de la Arrixaca, El Palmar, Murcia, Spain; Cátedra de Genética Médica, Universidad Católica de San Antonio (UCAM), Murcia, Spain; Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III (ISCIII), Madrid, Spain.

The IFITM5 gene has recently been found to be mutated in patients with autosomal dominant osteogenesis imperfecta (OI) type V. This form of OI is characterized by distinctive clinical manifestations, including hyperplastic callus formation at the site of fractures, calcification of the interosseous membrane of the forearm, and dislocation of the head of the radius. Notably, in spite of the fact that a considerable number of patients with IFITM5 mutations have been identified, to date all of them have been shown to have the same heterozygous mutation (c.-14C>T). Herein, we describe one patient with a de novo c.119C>T heterozygous mutation in IFITM5, which predicts p.Ser40Leu, and another with the recurrent c.-14C>T transition that was also apparently de novo. While the patient with the p.Ser40Leu mutation had none of the typical signs of OI type V and was diagnosed with limb shortening at prenatal stages, the patient with the c.-14C>T mutation developed hyperplastic calluses and had calcification of the forearm interosseous membrane. This study challenges the lack of allelic and clinical heterogeneity in IFITM5 mutations.
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http://dx.doi.org/10.1002/ajmg.a.36409DOI Listing
May 2014

Loss-of-function HDAC8 mutations cause a phenotypic spectrum of Cornelia de Lange syndrome-like features, ocular hypertelorism, large fontanelle and X-linked inheritance.

Hum Mol Genet 2014 Jun 8;23(11):2888-900. Epub 2014 Jan 8.

Sektion für Funktionelle Genetik am Institut für Humangenetik, Universität zu Lübeck, Lübeck 23538, Germany.

Cornelia de Lange syndrome (CdLS) is a multisystem genetic disorder with distinct facies, growth failure, intellectual disability, distal limb anomalies, gastrointestinal and neurological disease. Mutations in NIPBL, encoding a cohesin regulatory protein, account for >80% of cases with typical facies. Mutations in the core cohesin complex proteins, encoded by the SMC1A, SMC3 and RAD21 genes, together account for ∼5% of subjects, often with atypical CdLS features. Recently, we identified mutations in the X-linked gene HDAC8 as the cause of a small number of CdLS cases. Here, we report a cohort of 38 individuals with an emerging spectrum of features caused by HDAC8 mutations. For several individuals, the diagnosis of CdLS was not considered prior to genomic testing. Most mutations identified are missense and de novo. Many cases are heterozygous females, each with marked skewing of X-inactivation in peripheral blood DNA. We also identified eight hemizygous males who are more severely affected. The craniofacial appearance caused by HDAC8 mutations overlaps that of typical CdLS but often displays delayed anterior fontanelle closure, ocular hypertelorism, hooding of the eyelids, a broader nose and dental anomalies, which may be useful discriminating features. HDAC8 encodes the lysine deacetylase for the cohesin subunit SMC3 and analysis of the functional consequences of the missense mutations indicates that all cause a loss of enzymatic function. These data demonstrate that loss-of-function mutations in HDAC8 cause a range of overlapping human developmental phenotypes, including a phenotypically distinct subgroup of CdLS.
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http://dx.doi.org/10.1093/hmg/ddu002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4014191PMC
June 2014

GPI-anchor and GPI-anchored protein expression in PMM2-CDG patients.

Orphanet J Rare Dis 2013 Oct 20;8:170. Epub 2013 Oct 20.

Centro Regional de Hemodonación Servicio de Hematología y Oncología Médica, Hospital Universitario Morales Meseguer, Universidad de Murcia, Ronda de Garay S/N, 30003 Murcia, Spain.

Background: Mutations in PMM2 impair phosphomannomutase-2 activity and cause the most frequent congenital disorder of glycosylation, PMM2-CDG. Mannose-1-phosphate, that is deficient in this disorder, is also implicated in the biosynthesis of glycosylphosphatidyl inositol (GPI) anchors.

Objective: To evaluate whether GPI-anchor and GPI-anchored proteins are defective in PMM2-CDG patients.

Methods: The expression of GPI-anchor and seven GPI-anchored proteins was evaluated by flow cytometry in different cell types from twelve PMM2-CDG patients. Additionally, neutrophil CD16 and plasma hepatic proteins were studied by Western blot. Transferrin glycoforms were evaluated by HPLC.

Results: Patients and controls had similar surface expression of GPI-anchor and most GPI-anchored proteins. Nevertheless, patients displayed a significantly diminished binding of two anti-CD16 antibodies (3G8 and KD1) to neutrophils and also of anti-CD14 (61D3) to monocytes. Interestingly, CD16 immunostaining and asialotransferrin levels significantly correlated with patients' age. Analysis by flow cytometry of CD14 with MΦP9, and CD16 expression in neutrophils by Western blot using H-80 ruled out deficiencies of these antigens.

Conclusions: PMM2 mutations do not impair GPI-anchor or GPI-anchored protein expression. However, the glycosylation anomalies caused by PMM2 mutations might affect the immunoreactivity of monoclonal antibodies and lead to incorrect conclusions about the expression of different proteins, including GPI-anchored proteins. Neutrophils and monocytes are sensitive to PMM2 mutations, leading to abnormal glycosylation in immune receptors, which might potentially affect their affinity to their ligands, and contribute to infection. This study also confirms less severe hypoglycosylation defects in older PMM2-CDG patients.
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http://dx.doi.org/10.1186/1750-1172-8-170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4016514PMC
October 2013