Publications by authors named "Lorne A Clarke"

42 Publications

Newborn Screening for Mucopolysaccharidosis I: Moving Forward Learning from Experience.

Int J Neonatal Screen 2020 Nov 19;6(4). Epub 2020 Nov 19.

National MPS Society, Durham, NC 27707, USA.

There have been significant advances allowing for the integration of mucopolysaccharidosis I into newborn screening programs. Initial experiences using a single-tier approach for this disorder have highlighted shortcomings that require immediate remediation. The recent evaluation of a second-tier biomarker integrated into the MPS I newborn screening protocol has been demonstrated to greatly improve the precision and predictive value of newborn screening for this disorder. This commentary urges newborn screening programs to learn from these experiences and improve newborn screening for mucopolysaccharidosis I and future mucopolysaccharidoses newborn screening programs by implementation of a second-tier biomarker analyte.
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http://dx.doi.org/10.3390/ijns6040091DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7712368PMC
November 2020

Growth patterns for untreated individuals with MPS I: Report from the international MPS I registry.

Am J Med Genet A 2019 12 22;179(12):2425-2432. Epub 2019 Oct 22.

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

Mucopolysaccharidosis Type I (MPS I), caused by deficiency of α-L-iduronidase results in progressive, multisystemic disease with a broad phenotypic spectrum including patients with severe (Hurler syndrome) to attenuated (Hurler-Scheie and Scheie syndromes) disease. Disordered growth is common with either phenotype. The study objectives were to construct sex- and age-specific estimated length/height and head circumference growth curves for untreated individuals with severe and attenuated disease and compare them with clinical reference standards. Untreated individuals in the MPS I Registry with at least one observation for length/height and/or head circumference and assigned phenotype as of May 2017 were included. Median growth for 463 untreated individuals with severe disease deviated from reference growth curves by ~6 months of age and fell below the third percentile by 4 years of age. Median head circumference was above reference curves from 3 to 4 months through 3 years of age. Among 207 individuals with untreated attenuated disease, median height fell below the third percentile by 9 years of age with divergence from reference curves by 2 years of age. MPS I-specific growth curves will be useful in evaluation of long-term outcomes of therapeutics interventions and will provide a foundation for understanding the pathogenesis of skeletal disease in MPS I.
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http://dx.doi.org/10.1002/ajmg.a.61378DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899772PMC
December 2019

Genetic abnormalities in a large cohort of Coffin-Siris syndrome patients.

J Hum Genet 2019 Dec 17;64(12):1173-1186. Epub 2019 Sep 17.

Asahikawa-Kosei General Hospital, Hokkaido, Japan.

Coffin-Siris syndrome (CSS, MIM#135900) is a congenital disorder characterized by coarse facial features, intellectual disability, and hypoplasia of the fifth digit and nails. Pathogenic variants for CSS have been found in genes encoding proteins in the BAF (BRG1-associated factor) chromatin-remodeling complex. To date, more than 150 CSS patients with pathogenic variants in nine BAF-related genes have been reported. We previously reported 71 patients of whom 39 had pathogenic variants. Since then, we have recruited an additional 182 CSS-suspected patients. We performed comprehensive genetic analysis on these 182 patients and on the previously unresolved 32 patients, targeting pathogenic single nucleotide variants, short insertions/deletions and copy number variations (CNVs). We confirmed 78 pathogenic variations in 78 patients. Pathogenic variations in ARID1B, SMARCB1, SMARCA4, ARID1A, SOX11, SMARCE1, and PHF6 were identified in 48, 8, 7, 6, 4, 1, and 1 patients, respectively. In addition, we found three CNVs including SMARCA2. Of particular note, we found a partial deletion of SMARCB1 in one CSS patient and we thoroughly investigated the resulting abnormal transcripts.
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http://dx.doi.org/10.1038/s10038-019-0667-4DOI Listing
December 2019

Genotype-phenotype relationships in mucopolysaccharidosis type I (MPS I): Insights from the International MPS I Registry.

Clin Genet 2019 10 2;96(4):281-289. Epub 2019 Jul 2.

University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.

Mucopolysaccharidosis type I (MPS I) is a rare autosomal recessive disorder resulting from pathogenic variants in the α-L-iduronidase (IDUA) gene. Clinical phenotypes range from severe (Hurler syndrome) to attenuated (Hurler-Scheie and Scheie syndromes) and vary in age of onset, severity, and rate of progression. Defining the phenotype at diagnosis is essential for disease management. To date, no systematic analysis of genotype-phenotype correlation in large MPS I cohorts have been performed. Understanding genotype-phenotype is critical now that newborn screening for MPS I is being implemented. Data from 538 patients from the MPS I Registry (380 severe, 158 attenuated) who had 2 IDUA alleles identified were examined. In the 1076 alleles identified, 148 pathogenic variants were reported; of those, 75 were unique. Of the 538 genotypes, 147 (27%) were unique; 40% of patients with attenuated and 22% of patients with severe MPS I had unique genotypes. About 67.6% of severe patients had genotypes where both variants identified are predicted to severely disrupt protein/gene function and 96.1% of attenuated patients had at least one missense or intronic variant. This dataset illustrates a close genotype/phenotype correlation in MPS I but the presence of unique IDUA missense variants remains a challenge for disease prediction.
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http://dx.doi.org/10.1111/cge.13583DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6852151PMC
October 2019

Low-dose agalsidase beta treatment in male pediatric patients with Fabry disease: A 5-year randomized controlled trial.

Mol Genet Metab 2019 05 3;127(1):86-94. Epub 2019 Apr 3.

Department of Pediatric Metabolic Diseases, Emma Children's Hospital and Amsterdam Lysosome Center "Sphinx", Academic Medical Center, University Hospital of Amsterdam, Amsterdam, the Netherlands.

Background: Fabry disease is a rare, X-linked, lifelong progressive lysosomal storage disorder. Severely deficient α-galactosidase A activity in males is associated with the classic phenotype with early-onset, multisystem manifestations evolving to vital organ complications during adulthood. We assessed the ability of 2 low-dose agalsidase beta regimens to lower skin, plasma, and urine globotriaosylceramide (GL-3) levels, and influence clinical manifestations in male pediatric Fabry patients.

Methods: In this multicenter, open-label, parallel-group, phase 3b study, male patients aged 5-18 years were randomized to receive agalsidase beta at 0.5 mg/kg 2-weekly (n = 16) or 1.0 mg/kg 4-weekly (n = 15) for 5 years. All had plasma/urine GL-3 accumulation but no clinically evident organ involvement. The primary outcome was GL-3 accumulation in superficial skin capillary endothelium (SSCE).

Results: The mean age was 11.6 (range: 5-18) years and all but one of the 31 patients had classic GLA mutations. In the overall cohort, shifts from non-0 to 0-scores for SSCE GL-3 were significant at years 1, 3, and 5, but results were variable. Plasma GL-3 normalized and urine GL-3 reduced substantially. Higher anti-agalsidase beta antibody titers were associated with less robust SSCE GL-3 clearance and higher urine GL-3 levels. Renal function remained stable and normal. Most Fabry signs and symptoms tended to stabilize; abdominal pain was significantly reduced (-26.3%; P = .0215). No new clinical major organ complications were observed. GL-3 accumulation and cellular and vascular injury were present in baseline kidney biopsies (n = 7). Treatment effects on podocyte GL-3 content and foot process width were highly variable. Fabry arteriopathy overall increased in severity. Two patients withdrew and 2 had their agalsidase beta dose increased.

Conclusions: Our findings increase the limited amount of available data on long-term effects of enzyme replacement therapy in pediatric, classic Fabry patients. The low-dose regimens studied here over a period of 5 years did not demonstrate a consistent benefit among the patients in terms of controlling symptomatology, urine GL-3 levels, and pathological histology. The current available evidence supports treatment of pediatric, classic male Fabry patients at the approved agalsidase beta dose of 1.0 mg/kg 2-weekly if these patients are considered for enzyme replacement therapy with agalsidase beta.
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http://dx.doi.org/10.1016/j.ymgme.2019.03.010DOI Listing
May 2019

Burden of Illness in Acid Sphingomyelinase Deficiency: A Retrospective Chart Review of 100 Patients.

JIMD Rep 2018 12;41:119-129. Epub 2018 Jul 12.

Department of Pediatrics, Stony Brook University School of Medicine, Stony Brook, NY, USA.

Acid sphingomyelinase deficiency (ASMD) is a rare, progressive, and often fatal lysosomal storage disease caused by the deficiency of the enzyme acid sphingomyelinase (ASM) resulting in accumulation of sphingomyelin in target tissues. Little is known regarding predictors of disease-related morbidity, healthcare use, and lifestyle impact in adults with chronic disease. A multinational retrospective study collected data on the burden of illness and healthcare resource use for 100 patients across the clinical spectrum of ASMD, including those with rapidly progressive infantile neurovisceral disease (n = 13) and those with the more slowly progressive chronic neurovisceral (n = 6) and chronic visceral (n = 81) disease. Growth was subnormal throughout childhood for all patients with chronic neurovisceral disease and for 50% of patients with chronic visceral disease. Developmental delay, regression, and/or learning disabilities were reported in 40% of patients with chronic neurovisceral ASMD and 21% of patients with chronic visceral ASMD. Outpatient therapy or home healthcare was required for 50% of patients with chronic neurovisceral disease and 12% of patients with chronic visceral disease. Disease-related disability for patients with chronic disease resulted in need for home schooling for 16% of patients and compromised work ability for 22% of patients. Grade school was the highest level of education for 22% of patients older than 13 years of age.
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http://dx.doi.org/10.1007/8904_2018_120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6122055PMC
July 2018

Is it Fabry disease?

Genet Med 2016 12 19;18(12):1181-1185. Epub 2016 May 19.

Department of Medical Biochemistry, Leiden University, Leiden, The Netherlands.

Fabry disease is caused by mutations in the GLA gene that lower α-galactosidase A activity to less than 25-30% of the mean normal level. Several GLA variants have been identified that are associated with relatively elevated residual α-galactosidase A. The challenge is to determine which GLA variants can cause clinical manifestations related to Fabry disease. Here, we review the various types of GLA variants and recommend that pathogenicity be considered only when associated with elevated globotriaosylceramide in disease-relevant organs and tissues as analyzed by mass spectrometry. This criterion is necessary to ensure that very costly and specific therapy is provided only when appropriate.Genet Med 18 12, 1181-1185.
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http://dx.doi.org/10.1038/gim.2016.55DOI Listing
December 2016

12 year follow up of enzyme-replacement therapy in two siblings with attenuated mucopolysaccharidosis I: the important role of early treatment.

BMC Med Genet 2016 Mar 10;17:19. Epub 2016 Mar 10.

Pediatric Division, Department of Clinical Sciences, Polytechnic University of Marche, Ospedali Riuniti, Presidio Salesi, Via Corridoni 11, 60123, Ancona, Italy.

Background: Mucopolysaccharidosis type I is an autosomal recessive disorder caused by deficiency of α-L-iduronidase and characterized by a progressive course with multisystem involvement. Clinically, Mucopolysaccharidosis type I is classified into two forms: severe (Hurler syndrome), which presents in infancy and is characterized by rapid progressive neurological involvement and attenuated (Hurler/Scheie and Scheie syndromes), which presents with slower progression and absent to mild nervous system involvement. The specific treatment for attenuated Mucopolysaccharidosis type I consists of enzyme-replacement therapy with laronidase (human recombinant α-L-iduronidase, Aldurazyme). We present here the clinical and laboratory results in an 12-year-old patient affected by the attenuated form of Mucopolysaccharidosis type I treated by enzyme-replacement therapy from the age of 5 months, compared with his 17 year old affected sister, who started therapy at 5 years of age.

Case Presentation: Clinical evaluation of these siblings shows that initiation of therapy prior of the onset of clinically detectable disease resulted in considerable improvement in outcome in the young sibling. After 12 years of enzyme-replacement therapy, facial appearance, linear growth rate, and liver and spleen volumes were normal; moreover, the degree of joint disease, vertebral, and cardiac valvular involvement were only minimal compared with those of his sister.

Conclusion: This study demonstrates that early diagnosis and early initiation of enzyme-replacement therapy substantially modify the natural history of the attenuated form of Mucopolysaccharidosis type I.
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http://dx.doi.org/10.1186/s12881-016-0284-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4785727PMC
March 2016

Implementing evidence-driven individualized treatment plans within Morquio A Syndrome.

Mol Genet Metab 2016 Feb 29;117(2):217. Epub 2015 Dec 29.

Pulmonary Medicine, UCSF Benioff Children's Hospital, Oakland Campus, Oakland, California, USA.

Morquio A Syndrome (mucopolysaccharidosis IVA [MPS IVA]) is an inherited, autosomal recessive lysosomal storage disorder that occurs in ~1 in 200,000 to 300,000 live births.(1) (Online access http://www.elseviercme.com/559) Individuals with Morquio A Syndrome have mutations in the gene that encodes N-acetylgalactosamine-6-sulfate sulfatase (GALNS), an enzyme responsible for the metabolism of the glycosaminoglycans (GAGs) keratin sulfate and chondroitin-6-sulfate.(2-4) Reduced activity or lack of GALNS leads to cellular and tissue accumulation of these GAGs to result in progressive, multisystem dysfunction and impaired functional capacity.(5) Individuals with Morquio A Syndrome suffer from a broad spectrum of impairment, including a variety of widespread skeletal abnormalities, respiratory compromise, valvular heart disease, visual and auditory impairments, and dental abnormalities.(6-8) Cognition is not typically affected.(9) Morquio A Syndrome exhibits extensive allelic heterogeneity, which results in extensive clinical heterogeneity.(2-4) This educational intervention on the management of patients with Morquio A Syndrome provides updated information and guidelines concerning the early and accurate diagnosis as well as an earlier intervention to improve patient outcomes. The activity is based on a live satellite symposium conducted during the 2015 official ACMG Annual Clinical Genetics Meeting program. Recent advances in the science of enzyme replacement therapies have presented opportunities for pharmacological interventions that improve quality of life. Clinicians will be updated on the clinical trial data and practical solutions for applying newer therapeutics to daily practice. Strategies to manage cardiopulmonary comorbidities and recommendations for the ideal clinical care model will wrap up this informative and up-to-date review of Morquio A Syndrome. This CME activity is also available through the Website of Molecular Genetics and Metabolism. Click on the CME button in the navigation bar for full access. Or access: http://www.elseviercme.com/559.
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http://dx.doi.org/10.1016/j.ymgme.2015.12.157DOI Listing
February 2016

The clinical spectrum and pathophysiology of skeletal complications in lysosomal storage disorders.

Best Pract Res Clin Endocrinol Metab 2015 Mar 27;29(2):219-35. Epub 2014 Aug 27.

Department of Internal Medicine/Endocrinology and Metabolism, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. Electronic address:

Lysosomal storage disorders affect multiple organs including the skeleton. Disorders with prominent skeletal symptoms are type 1 and 3 Gaucher disease, the mucopolysaccharidoses, the glycoproteinoses and pycnodysostosis. Clinical manifestations range from asymptomatic radiographical evidence of bone pathology to overt bone crises (Gaucher), short stature with typical imaging features known as dysostosis multiplex (MPS), with spine and joint deformities (mucopolysaccharidoses, mucolipidosis), or osteopetrosis with pathological fractures (pynodysostosis). The pathophysiology of skeletal disease is only partially understood and involves direct substrate storage, inflammation and other complex alterations of cartilage and bone metabolism. Current treatments are enzyme replacement therapy, substrate reduction therapy and hematopoietic stem cell transplantation. However, effects of these interventions on skeletal disease manifestations are less well established and outcomes are highly dependent on disease burden at treatment initiation. It is now clear that adjunctive treatments that target skeletal disease are needed and should be part of future research agenda.
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http://dx.doi.org/10.1016/j.beem.2014.08.010DOI Listing
March 2015

Characterization of early disease status in treatment-naive male paediatric patients with Fabry disease enrolled in a randomized clinical trial.

PLoS One 2015 8;10(5):e0124987. Epub 2015 May 8.

Royal Free Hospital, London, United Kingdom.

Trial Design: This analysis characterizes the degree of early organ involvement in a cohort of oligo-symptomatic untreated young patients with Fabry disease enrolled in an ongoing randomized, open-label, parallel-group, phase 3B clinical trial.

Methods: Males aged 5-18 years with complete α-galactosidase A deficiency, without symptoms of major organ damage, were enrolled in a phase 3B trial evaluating two doses of agalsidase beta. Baseline disease characteristics of 31 eligible patients (median age 12 years) were studied, including cellular globotriaosylceramide (GL-3) accumulation in skin (n = 31) and kidney biopsy (n = 6; median age 15 years; range 13-17 years), renal function, and glycolipid levels (plasma, urine).

Results: Plasma and urinary GL-3 levels were abnormal in 25 of 30 and 31 of 31 patients, respectively. Plasma lyso-GL-3 was elevated in all patients. GL-3 accumulation was documented in superficial skin capillary endothelial cells (23/31 patients) and deep vessel endothelial cells (23/29 patients). The mean glomerular filtration rate (GFR), measured by plasma disappearance of iohexol, was 118.1 mL/min/1.73 m(2) (range 90.4-161.0 mL/min/1.73 m(2)) and the median urinary albumin/creatinine ratio was 10 mg/g (range 4.0-27.0 mg/g). On electron microscopy, renal biopsy revealed GL-3 accumulation in all glomerular cell types (podocytes and parietal, endothelial, and mesangial cells), as well as in peritubular capillary and non-capillary endothelial, interstitial, vascular smooth muscle, and distal tubules/collecting duct cells. Lesions indicative of early Fabry arteriopathy and segmental effacement of podocyte foot processes were found in all 6 patients.

Conclusions: These data reveal that in this small cohort of children with Fabry disease, histological evidence of GL-3 accumulation, and cellular and vascular injury are present in renal tissues at very early stages of the disease, and are noted before onset of microalbuminuria and development of clinically significant renal events (e.g. reduced GFR). These data give additional support to the consideration of early initiation of enzyme replacement therapy, potentially improving long-term outcome.

Trial Registration: ClinicalTrials.gov NCT00701415.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0124987PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425695PMC
February 2016

Extracellular matrix disruption is an early event in the pathogenesis of skeletal disease in mucopolysaccharidosis I.

Mol Genet Metab 2015 Feb 7;114(2):146-55. Epub 2014 Oct 7.

Department of Medical Genetics, University of British Columbia, 950 West 28 Avenue, Vancouver, British Columbia V5Z-4H4, Canada; The Child and Family Research Institute, University of British Columbia, 950 West 28 Avenue, Vancouver, British Columbia V5Z-4H4, Canada. Electronic address:

Progressive skeletal and connective tissue disease represents a significant clinical burden in all of the mucopolysaccharidoses. Despite the introduction of enzyme replacement strategies for many of the mucopolysaccharidoses, symptomatology related to bone and joint disease appears to be recalcitrant to current therapies. In order to address these unmet medical needs a clearer understanding of skeletal and connective tissue disease pathogenesis is required. Historically the pathogenesis of the mucopolysaccharidoses has been assumed to directly relate to progressive storage of glycosaminoglycans. It is now apparent for many lysosomal storage disorders that more complex pathogenic mechanisms underlie patients' clinical symptoms. We have used proteomic and genome wide expression studies in the murine mucopolysaccharidosis I model to identify early pathogenic events occurring in micro-dissected growth plate tissue. Studies were conducted using 3 and 5-week-old mice thus representing a time at which no obvious morphological changes of bone or joints have taken place. An unbiased iTRAQ differential proteomic approach was used to identify candidates followed by validation with multiple reaction monitoring mass spectrometry and immunohistochemistry. These studies reveal significant decreases in six key structural and signaling extracellular matrix proteins; biglycan, fibromodulin, PRELP, type I collagen, lactotransferrin, and SERPINF1. Genome-wide expression studies in embryonic day 13.5 limb cartilage and 5 week growth plate cartilage followed by specific gene candidate qPCR studies in the 5week growth plate identified fourteen significantly deregulated mRNAs (Adamts12, Aspn, Chad, Col2a1, Col9a1, Hapln4, Lum, Matn1, Mmp3, Ogn, Omd, P4ha2, Prelp, and Rab32). The involvement of biglycan, PRELP and fibromodulin; all members of the small leucine repeat proteoglycan family is intriguing, as this protein family is implicated in the pathogenesis of late onset osteoarthritis. Taken as a whole, our data indicates that alteration of the extracellular matrix represents a very early event in the pathogenesis of the mucopolysaccharidoses and implies that biomechanical failure of chondro-osseous tissue may underlie progressive bone and joint disease symptoms. These findings have important therapeutic implications.
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http://dx.doi.org/10.1016/j.ymgme.2014.09.012DOI Listing
February 2015

Mucopolysaccharidosis IVA (Morquio A syndrome) and VI (Maroteaux-Lamy syndrome): under-recognized and challenging to diagnose.

Skeletal Radiol 2014 Mar 4;43(3):359-69. Epub 2014 Jan 4.

International Skeletal Dysplasia Registry, Cedars-Sinai Medical Center/University of California, Los Angeles, Los Angeles, CA, USA,

Objective: Mucopolysaccharidosis IVA (MPS IVA, or Morquio A syndrome) and VI (MPS VI, or Maroteaux-Lamy syndrome) are autosomal recessive lysosomal storage disorders. Skeletal abnormalities are common initial presenting symptoms and, when recognized early, may facilitate timely diagnosis and intervention, leading to improved patient outcomes. Patients with slowly progressing disease and nonclassic phenotypes can be particularly challenging to diagnose. The objective was to describe the radiographic features of patients with a delayed diagnosis of MPS IVA or VI.

Materials And Methods: This was a retrospective study. The records of 5 MPS IVA and 3 MPS VI patients with delayed diagnosis were reviewed. Radiographs were evaluated by a radiologist with special expertise in skeletal dysplasias.

Results: An important common theme in these cases was the appearance of multiple epiphyseal dysplasia (MED) with epiphyseal changes seemingly confined to the capital (proximal) femoral epiphyses. Very few patients had the skeletal features of classical dysostosis multiplex.

Conclusions: Radiologists should appreciate the wide phenotypic variability of MPS IVA and VI. The cases presented here illustrate the importance of considering MPS in the differential diagnosis of certain skeletal dysplasias/disorders, including MED, some forms of spondylo-epiphyseal dysplasia (SED), and bilateral Perthes-like disease. It is important to combine radiographic findings with clinical information to facilitate early testing and accurate diagnosis.
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http://dx.doi.org/10.1007/s00256-013-1797-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3901942PMC
March 2014

Transgenic mice expressing human glucocerebrosidase variants: utility for the study of Gaucher disease.

Blood Cells Mol Dis 2013 Aug 30;51(2):109-15. Epub 2013 Apr 30.

Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada.

Gaucher disease is an autosomal recessively inherited storage disorder caused by deficiency of the lysosomal hydrolase, acid β-glucosidase. The disease manifestations seen in Gaucher patients are highly heterogeneous as is the responsiveness to therapy. The elucidation of the precise factors responsible for this heterogeneity has been challenging as the development of clinically relevant animal models of Gaucher disease has been problematic. Although numerous murine models for Gaucher disease have been described each has limitations in their specific utility. We describe here, transgenic murine models of Gaucher disease that will be particularly useful for the study of pharmacological chaperones. We have produced stable transgenic mouse strains that individually express wild type, N370S and L444P containing human acid β-glucosidase and show that each of these transgenic lines rescues the lethal phenotype characteristic of acid β-glucosidase null mice. Both the N370S and L444P transgenic models show early and progressive elevations of tissue sphingolipids with L444P mice developing progressive splenic Gaucher cell infiltration. We demonstrate the potential utility of these new transgenic models for the study of Gaucher disease pathogenesis. In addition, since these mice produce only human enzyme, they are particularly relevant for the study of pharmacological chaperones that are specifically targeted to human acid β-glucosidase and the common mutations underlying Gaucher disease.
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http://dx.doi.org/10.1016/j.bcmd.2013.03.006DOI Listing
August 2013

Production of α-L-iduronidase in maize for the potential treatment of a human lysosomal storage disease.

Nat Commun 2012 ;3:1062

Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.

Lysosomal storage diseases are a class of over 70 rare genetic diseases that are amenable to enzyme replacement therapy. Towards developing a plant-based enzyme replacement therapeutic for the lysosomal storage disease mucopolysaccharidosis I, here we expressed α-L-iduronidase in the endosperm of maize seeds by a previously uncharacterized mRNA-targeting-based mechanism. Immunolocalization, cellular fractionation and in situ RT-PCR demonstrate that the α-L-iduronidase protein and mRNA are targeted to endoplasmic reticulum (ER)-derived protein bodies and to protein body-ER regions, respectively, using regulatory (5'- and 3'-UTR) and signal-peptide coding sequences from the γ-zein gene. The maize α-L-iduronidase exhibits high activity, contains high-mannose N-glycans and is amenable to in vitro phosphorylation. This mRNA-based strategy is of widespread importance as plant N-glycan maturation is controlled and the therapeutic protein is generated in a native form. For our target enzyme, the N-glycan structures are appropriate for downstream processing, a prerequisite for its potential as a therapeutic protein.
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http://dx.doi.org/10.1038/ncomms2070DOI Listing
February 2013

Left ventricular aneurysm in an adult patient with mucopolysaccharidosis type I: comment on pathogenesis of a novel complication.

Mol Genet Metab 2012 Aug 13;106(4):470-3. Epub 2012 Jun 13.

Division of Cardiology, Del Viso Medical Group, Buenos Aires, Argentina.

Mucopolysaccharidosis type I (MPS I) is a rare autosomal recessive disease caused by deficiency of the lysosomal enzyme alpha-L-iduronidase. This enzyme is involved in the degradation of the glycosaminoglycans (GAGs) dermatan and heparan sulphate and its deficiency results in the accumulation of GAGs and a progressive multisystem disease. Cardiac involvement is common in MPS patients and usually consists of progressive valvular thickening with incompetence and cardiomyopathy. We present an attenuated MPS I patient with a primary apical left ventricular aneurysm not associated with ischemia. We speculate that the defect in GAG catabolism leads not only to the storage of GAGs but also to alterations of the myocardial extracellular matrix. The latter ultimately being responsible for the formation of the aneurysm. This case emphasizes the importance of careful surveillance for cardiac lesions in MPS patients.
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http://dx.doi.org/10.1016/j.ymgme.2012.06.001DOI Listing
August 2012

Biomarkers for the mucopolysaccharidoses: discovery and clinical utility.

Mol Genet Metab 2012 Aug 14;106(4):395-402. Epub 2012 May 14.

Department of Medical Genetics, Child and Family Research Institute, University of British Columbia, Vancouver, BC, Canada.

The mucopolysaccharidoses (MPSs), a group of inherited lysosomal storage diseases, are complex, progressive, multisystem disorders with extreme clinical heterogeneity. The introduction of therapies that target the underlying enzyme deficiency in a number of the MPSs has brought to light the need for biomarkers that would aid in the evaluation of disease burden and as a means to objectively measure therapeutic response in individual patients. It is increasingly recognized that due to the extraordinarily complex pathogenesis of the MPSs, achieving these goals with a single analyte, such as urinary glycosaminoglycans, is unlikely. This recognition has created an impetus for the search for clinically useful biomarkers that reflect the disease pathogenesis and that are stage- or organ-specific. In this review, the current state of MPS biomarker research is discussed, with a focus on clinical utility in the MPSs.
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http://dx.doi.org/10.1016/j.ymgme.2012.05.003DOI Listing
August 2012

Capturing phenotypic heterogeneity in MPS I: results of an international consensus procedure.

Orphanet J Rare Dis 2012 Apr 23;7:22. Epub 2012 Apr 23.

Department of Paediatrics, Academic Medical Center, University Hospital of Amsterdam H7-270, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.

Background: Mucopolysaccharidosis type I (MPS I) is traditionally divided into three phenotypes: the severe Hurler (MPS I-H) phenotype, the intermediate Hurler-Scheie (MPS I-H/S) phenotype and the attenuated Scheie (MPS I-S) phenotype. However, there are no clear criteria for delineating the different phenotypes. Because decisions about optimal treatment (enzyme replacement therapy or hematopoietic stem cell transplantation) need to be made quickly and depend on the presumed phenotype, an assessment of phenotypic severity should be performed soon after diagnosis. Therefore, a numerical severity scale for classifying different MPS I phenotypes at diagnosis based on clinical signs and symptoms was developed.

Methods: A consensus procedure based on a combined modified Delphi method and a nominal group technique was undertaken. It consisted of two written rounds and a face-to-face meeting. Sixteen MPS I experts participated in the process. The main goal was to identify the most important indicators of phenotypic severity and include these in a numerical severity scale. The correlation between the median subjective expert MPS I rating and the scores derived from this severity scale was used as an indicator of validity.

Results: Full consensus was reached on six key clinical items for assessing severity: age of onset of signs and symptoms, developmental delay, joint stiffness/arthropathy/contractures, kyphosis, cardiomyopathy and large head/frontal bossing. Due to the remarkably large variability in the expert MPS I assessments, however, a reliable numerical scale could not be constructed. Because of this variability, such a scale would always result in patients whose calculated severity score differed unacceptably from the median expert severity score, which was considered to be the 'gold standard'.

Conclusions: Although consensus was reached on the six key items for assessing phenotypic severity in MPS I, expert opinion on phenotypic severity at diagnosis proved to be highly variable. This subjectivity emphasizes the need for validated biomarkers and improved genotype-phenotype correlations that can be incorporated into phenotypic severity assessments at diagnosis.
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http://dx.doi.org/10.1186/1750-1172-7-22DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3379958PMC
April 2012

Pathogenesis of skeletal and connective tissue involvement in the mucopolysaccharidoses: glycosaminoglycan storage is merely the instigator.

Authors:
Lorne A Clarke

Rheumatology (Oxford) 2011 Dec;50 Suppl 5:v13-8

Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, BC, Canada.

The mucopolysaccharidoses (MPSs) are a series of rare genetic disorders in which progressive bone and joint disease represents a key source of morbidity for patients. The recent introduction of enzyme replacement therapy for many of the MPSs has led to a need for increased physician awareness of these rare conditions in order to ensure that treatment is initiated at a time that leads to optimal benefit for patients. In addition, the current experiences of the clinical responsiveness of patient's symptoms to enzyme replacement approaches have also fuelled an interest in the development of alternative and adjunctive therapeutic approaches directed particularly to the rheumatological aspects of disease. Understanding the underlying pathogenesis of the MPSs is a key element for advancements in both of these areas. This review highlights the current knowledge underlying the pathophysiology of disease symptoms in the MPSs and underscores the importance and role of pathogenic cascades.
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http://dx.doi.org/10.1093/rheumatology/ker395DOI Listing
December 2011

Production of active human glucocerebrosidase in seeds of Arabidopsis thaliana complex-glycan-deficient (cgl) plants.

Glycobiology 2012 Apr 7;22(4):492-503. Epub 2011 Nov 7.

Department of Biological Sciences, Simon Fraser University, 8888 University Dr., Burnaby, British Columbia, V5A 1S6, Canada.

There is a clear need for efficient methods to produce protein therapeutics requiring mannose-termination for therapeutic efficacy. Here we report on a unique system for production of active human lysosomal acid β-glucosidase (glucocerebrosidase, GCase, EC 3.2.1.45) using seeds of the Arabidopsis thaliana complex-glycan-deficient (cgl) mutant, which are deficient in the activity of N-acetylglucosaminyl transferase I (EC 2.4.1.101). Gaucher disease is a prevalent lysosomal storage disease in which affected individuals inherit mutations in the gene (GBA1) encoding GCase. A gene cassette optimized for seed expression was used to generate the human enzyme in seeds of the cgl (C5) mutant, and the recombinant GCase was mainly accumulated in the apoplast. Importantly, the enzymatic properties including kinetic parameters, half-maximal inhibitory concentration of isofagomine and thermal stability of the cgl-derived GCase were comparable with those of imiglucerase, a commercially available recombinant human GCase used for enzyme replacement therapy in Gaucher patients. N-glycan structural analyses of recombinant cgl-GCase showed that the majority of the N-glycans (97%) were mannose terminated. Additional purification was required to remove ∼15% of the plant-derived recombinant GCase that possessed potentially immunogenic (xylose- and/or fucose-containing) N-glycans. Uptake of cgl-derived GCase by mouse macrophages was similar to that of imiglucerase. The cgl seed system requires no addition of foreign (non-native) amino acids to the mature recombinant GCase protein, and the dry transgenic seeds represent a stable repository of the therapeutic protein. Other strategies that may completely prevent plant-like complex N-glycans are discussed, including the use of a null cgl mutant.
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http://dx.doi.org/10.1093/glycob/cwr157DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3425599PMC
April 2012

Laronidase for the treatment of mucopolysaccharidosis type I.

Authors:
Lorne A Clarke

Expert Rev Endocrinol Metab 2011 Nov;6(6):755-768

a Department of Medical Genetics, University of British Columbia, Child and Family Research Institute, 4500 Oak Street, RM C234, Vancouver, British Columbia, V6H-3N1, Canada.

A decade has passed since the initial report that parenteral use of recombinant human α-L-iduronidase results in amelioration of symptoms in patients with mucopolysaccharidosis type I (MPS I). As a result, MPS I became the first mucopolysaccharide storage disorder to benefit from enzyme replacement therapy (ERT); subsequent ERTs have been approved for MPS II and VI. The ability of lysosomal storage disorders to respond to ERT is unique among genetic disorders and relates to the capability of cells to take up recombinant lysosomal enzymes through cell surface receptors and deliver them to the lysosome, a processed coined as 'cross-correction'. Although the concept of ERT is straightforward, the evaluation of its efficacy in disorders like MPS I is challenging. This article reviews the use of laronidase in the management of MPS I, with a particular emphasis on the unique issues inherent in the evaluation of therapeutics for such a rare, complex and progressive disorder.
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http://dx.doi.org/10.1586/eem.11.72DOI Listing
November 2011

Imaging of enzyme replacement therapy using PET.

Proc Natl Acad Sci U S A 2010 Jun 1;107(24):10842-7. Epub 2010 Jun 1.

Tri-University Meson Facility, 4004 Wesbrook Mall, Vancouver, BC, Canada.

Direct enzyme replacement therapy (ERT) has been introduced as a means to treat a number of rare, complex genetic conditions associated with lysosomal dysfunction. Gaucher disease was the first for which this therapy was applied and remains the prototypical example. Although ERT using recombinant lysosomal enzymes has been shown to be effective in altering the clinical course of Gaucher disease, Fabry disease, Hurler syndrome, Hunter syndrome, Maroteaux-Lamy syndrome, and Pompe disease, the recalcitrance of certain disease manifestations underscores important unanswered questions related to dosing regimes, tissue half-life of the recombinant enzyme and the ability of intravenously administered enzyme to reach critical sites of known disease pathology. We have developed an innovative method for tagging acid beta-glucocerebrosidase (GCase), the recombinant enzyme formulated in Cerezyme(R) used to treat Gaucher disease, using an (18)F-labeled substrate analogue that becomes trapped within the active site of the enzyme. Using micro-PET we show that the tissue distribution of injected enzyme can be imaged in a murine model and that the PET data correlate with tissue (18)F counts. Further we show that PET imaging readily monitors pharmacokinetic changes effected by receptor blocking. The ability to (18)F-label GCase to monitor the enzyme distribution and tissue half-life in vivo by PET provides a powerful research tool with an immediate clinical application to Gaucher disease and a clear path for application to other ERTs.
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http://dx.doi.org/10.1073/pnas.1003247107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890769PMC
June 2010

Urolithiasis and hepatotoxicity are linked to the anion transporter Sat1 in mice.

J Clin Invest 2010 Mar 15;120(3):706-12. Epub 2010 Feb 15.

School of Biomedical Sciences, University of Queensland, Brisbane, Australia.

Urolithiasis, a condition in which stones are present in the urinary system, including the kidneys and bladder, is a poorly understood yet common disorder worldwide that leads to significant health care costs, morbidity, and work loss. Acetaminophen-induced liver damage is a major cause of death in patients with acute liver failure. Kidney and urinary stones and liver toxicity are disturbances linked to alterations in oxalate and sulfate homeostasis, respectively. The sulfate anion transporter-1 (Sat1; also known as Slc26a1) mediates epithelial transport of oxalate and sulfate, and its localization in the kidney, liver, and intestine suggests that it may play a role in oxalate and sulfate homeostasis. To determine the physiological roles of Sat1, we created Sat1-/- mice by gene disruption. These mice exhibited hyperoxaluria with hyperoxalemia, nephrocalcinosis, and calcium oxalate stones in their renal tubules and bladder. Sat1-/- mice also displayed hypersulfaturia, hyposulfatemia, and enhanced acetaminophen-induced liver toxicity. These data suggest that Sat1 regulates both oxalate and sulfate homeostasis and may be critical to the development of calcium oxalate urolithiasis and hepatotoxicity.
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http://dx.doi.org/10.1172/JCI31474DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2827940PMC
March 2010

Enzyme-replacement therapy in a 5-month-old boy with attenuated presymptomatic MPS I: 5-year follow-up.

Pediatrics 2010 Jan 21;125(1):e183-7. Epub 2009 Dec 21.

Institute of Maternal-Infantile Sciences, Polytechnic University of Marche, Ancona, Italy.

Mucopolysaccharidosis type I (MPS I) is a progressive and multisystemic disease, even in its attenuated Hurler-Scheie and Scheie forms. Clinical trials of enzyme-replacement therapy in MPS I have shown clinical benefit in patients with considerable preexisting disease, but no data exist on the effect of beginning enzyme replacement before the onset of significant clinical signs of disease. Here we present the 5-year follow-up of a boy with attenuated MPS I who had laronidase therapy initiated at the age of 5 months and compare his clinical course to that of his older sister, who began treatment at 5 years of age after she had developed typical signs of MPS I. After 5 years of treatment, the younger sibling has not developed any clinical manifestations of MPS I except for mild corneal clouding. In contrast, although many of the older sibling's clinical features have improved after 5 years of treatment, her dysostosis multiplex, cardiac valve involvement, and corneal clouding, although stabilized, have persisted. We suggest that early treatment of attenuated MPS I may significantly delay or prevent the onset of the major clinical signs, substantially modifying the natural history of the disease.
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http://dx.doi.org/10.1542/peds.2009-1728DOI Listing
January 2010

Characterization of an MPS I-H knock-in mouse that carries a nonsense mutation analogous to the human IDUA-W402X mutation.

Mol Genet Metab 2010 Jan;99(1):62-71

Department of Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.

Here we report the characterization of a knock-in mouse model for the autosomal recessive disorder mucopolysaccharidosis type I-Hurler (MPS I-H), also known as Hurler syndrome. MPS I-H is the most severe form of alpha-l-iduronidase deficiency. alpha-l-iduronidase (encoded by the IDUA gene) is a lysosomal enzyme that participates in the degradation of dermatan sulfate and heparan sulfate. Using gene replacement methodology, a nucleotide change was introduced into the mouse Idua locus that resulted in a nonsense mutation at codon W392. The Idua-W392X mutation is analogous to the human IDUA-W402X mutation commonly found in MPS I-H patients. We found that the phenotype in homozygous Idua-W392X mice closely correlated with the human MPS I-H disease. Homozygous W392X mice showed no detectable alpha-l-iduronidase activity. We observed a defect in GAG degradation as evidenced by an increase in sulfated GAGs excreted in the urine and stored in multiple tissues. Histology and electron microscopy also revealed evidence of GAG storage in all tissues examined. Additional assessment revealed bone abnormalities and altered metabolism within the Idua-W392X mouse. This new mouse will provide an important tool to investigate therapeutic approaches for MPS I-H that cannot be addressed using current MPS I-H animal models.
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http://dx.doi.org/10.1016/j.ymgme.2009.08.002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2795040PMC
January 2010

Long-term efficacy and safety of laronidase in the treatment of mucopolysaccharidosis I.

Pediatrics 2009 Jan;123(1):229-40

University of British Columbia, Department of Medical Genetics, Vancouver, British Columbia, Canada.

Objective: Our goal was to evaluate the long-term safety and efficacy of recombinant human alpha-l-iduronidase (laronidase) in patients with mucopolysaccharidosis I.

Patients And Methods: All 45 patients who completed a 26-week, double-blind, placebo-controlled trial of laronidase were enrolled in a 3.5-year open-label extension study. Mean patient age at baseline was 16 (range: 6-43) years. All patients had attenuated disease (84% Hurler-Scheie, 16% Scheie phenotypes). Clinical, biochemical, and health outcomes measures were evaluated through the extension phase. Changes are presented as the mean +/- SEM.

Results: All 40 patients (89%) who completed the trial received at least 80% of scheduled infusions. As shown in earlier trials, urinary glycosaminoglycan levels decreased within the first 12 weeks and liver volume decreased within the first year. Percent predicted forced vital capacity remained stable, with a linear slope of -0.78 percentage points per year. The 6-minute walk distance increased 31.7 +/- 10.2 m in the first 2 years, with a final gain of 17.1 +/- 16.8 m. Improvements in the apnea/hypopnea index (decrease of 7.6 +/- 4.5 events per hour among the patients with significant baseline sleep apnea) and shoulder flexion (increase of 17.4 degrees +/- 3.6 degrees) were most rapid during the first 2 years. Improvements in the Child Health Assessment Questionnaire/Health Assessment Questionnaire disability index (decrease of 0.31 +/- 0.11, signifying a clinically meaningful improvement in activities of daily living) were gradual and sustained over the treatment period. Laronidase infusions were generally well tolerated except in 1 patient who experienced an anaphylactic reaction. Infusion-associated reactions, which occurred in 53% of the patients, were mostly mild, easily managed, and decreased markedly after 6 months. One patient died as a result of an upper respiratory infection unrelated to treatment. Antibodies to laronidase developed in 93% of the patients; 29% of the patients were seronegative at their last assessment.

Conclusions: This trial demonstrates the long-term clinical benefit and safety of laronidase in attenuated patients with mucopolysaccharidosis I and highlights the magnitude and chronology of treatment effects. Prompt diagnosis and early treatment will maximize treatment outcomes.
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http://dx.doi.org/10.1542/peds.2007-3847DOI Listing
January 2009

Mucopolysaccharidosis I: management and treatment guidelines.

Pediatrics 2009 Jan;123(1):19-29

Department of Pediatrics, University of North Carolina at Chapel Hill, Chapel Hill, NC 27514, USA.

Objective: Disease management for mucopolysaccharidosis type I has been inconsistent because of disease rarity (approximately 1 case per 100,000 live births), phenotypic heterogeneity, and limited therapeutic options. The availability of hematopoietic stem cell transplantation and the recent introduction of enzyme replacement therapy for mucopolysaccharidosis I necessitate the establishment of system-specific management guidelines for this condition.

Methods: Twelve international experts on mucopolysaccharidosis I met in January 2003 to draft management and treatment guidelines for mucopolysaccharidosis I. Initial guidelines were revised and updated in 2008, on the basis of additional clinical data and therapeutic advances. Recommendations are based on our extensive clinical experience and a review of the literature.

Results: All patients with mucopolysaccharidosis I should receive a comprehensive baseline evaluation, including neurologic, ophthalmologic, auditory, cardiac, respiratory, gastrointestinal, and musculoskeletal assessments, and should be monitored every 6 to 12 months with individualized specialty assessments, to monitor disease progression and effects of intervention. Patients are best treated by a multidisciplinary team. Treatments consist of palliative/supportive care, hematopoietic stem cell transplantation, and enzyme replacement therapy. The patient's age (>2 years or < or =2 years), predicted phenotype, and developmental quotient help define the risk/benefit profile for hematopoietic stem cell transplantation (higher risk but can preserve central nervous system function) versus enzyme replacement therapy (low risk but cannot cross the blood-brain barrier).

Conclusion: We anticipate that provision of a standard of care for the treatment of patients with mucopolysaccharidosis I will optimize clinical outcomes and patients' quality of life.
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http://dx.doi.org/10.1542/peds.2008-0416DOI Listing
January 2009