Abstracts / Molecular Genetics and Metabolism 96 (2009) S12–S47 MPS IV, or Morquio disease, is an autosomal recessive lysosomal storage disorder due to deficiency of N-acetyl-galactosamine-6-sulphatase (MPS IVA) or beta-galactosidase (MPS IVB). The aim of this study was to describe the Argentinean experience in first assessment and biochemical diagnosis of the disease. Results: Of a total of 36 patients, MPS IVA was diagnosed in 33 (92%) and MPS IV B in 3 (8%) through enzymatic assay. All but one (3%) had abnormal urinary excretion of keratan sulphate in urine. The referring physician speciality was: paediatrician 36%, geneticist 36%, pediatric neurologist 21% and orthopedistt 7%. At the time of diagnosis, disostosis was present in all the patients 100%, liver and spleen enlargement in 16% and corneal clouding in 13%. Median age at the diagnosis was 3.5 years old. Conclusions: At our knowledge, this is one of the largest populations of MPS IV 4s patients. Detailed reports on this pathology would probably allow its earlier recognition and a better therapeutic approach. doi:10.1016/j.ymgme.2008.11.122
122. Mucolipidosis type IV is both a developmental brain disease and a degenerative retinopathy Raphael Schiffmanna, Rafael Carusob, Ehud Goldinc, aInstitute of Metabolic Disease, Dallas, TX, USA, bNational Eye Institute, Bethesda, Maryland, USA, cNational Human Genome Research Institute, Bethesda, Maryland, USA Background: Mucolipidosis type IV (MLIV) is a rare autosomal recessive neurodegenerative disease caused by mutations of MCOLN1, which codes of mucolipin-1 a putative cation channel located in lysosomes. This research proposal aims to study the natural history of neurological and retinal manifestations of MLIV It also aims to increase awareness and improve diagnosis of MLIV among patients with cerebral palsy and those with retinal dystrophy of unknown cause. Over the past decade we have been studying prospectively various clinical and genetic aspects of MLIV in the only study of its kind. Hypothesis: We hypothesize that MLIV is a combination of mostly developmental abnormality in the CNS and a degenerative retinal process. Proposal: In this application we propose to (1) recruit known and newly diagnosed patients with MLIV and systematically study the neurological and retinal function over time. (2) Contact practicing physicians that take care of cerebral palsy patients and those with retinal dystrophy to increased awareness and improve diagnosis of MLIV. Based on our experience, we believe that many MLIV patients go undiagnosed. Conclusions: This project will help characterize and quantify the clinical abnormalities of MLIV and thus help define a patient population and outcome measures for future clinical trials.
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conjugated sphingomyelin as substrate, tissue extracts from the R496L line had no detectable residual ASM activity, despite normal levels of RNA expression. In contrast, expression was detectable in each of the three R608 lines, consistent with the clinical phenotypes of patients carrying these mutations. Studies are currently underway to characterize the clinical and pathological findings in these animals, and in the future they will be used to evaluate new approaches to enhance the residual enzymatic activities. doi:10.1016/j.ymgme.2008.11.124
124. Retention of lysosomal protein CLN5 in the endoplasmic reticulum causes neuronal ceroid lipofuscinosis in Asian sibship Angela Schulza, Anne-Helene Lebruna, Stephan Storcha, Rschendorf Franzb, Mia-Lisa Schmiedtc, Aija Kyttdlldc, Sara E. Moled, Claudia Kitzmllerd, Leena D. Mewasinghe, Volker Bodaf, Kurt Ullricha, Alfried Kohlschttera, Thomas Braulkea, aUniversity Medical Center Hamburg, Hamburg, Germany, bMax Delbrck Center, Berlin, Germany, cNational Public Health Institute, and Institute for Molecular Medicine Finland, Helsinki, Finland, d University College of London, UK, eSt. Mary’s Hospital, Imperial College Healthcare NHS Trust, London, UK, fUniversity Hospital Frankfurt, Frankfurt, Germany The neuronal ceroid lipofuscinoses (NCLs) form a group of autosomal recessively inherited neurodegenerative disorders that mainly affect children. Ten NCL forms can be distinguished by age at onset, clinicopathologic features, and genetics. In eight of these forms, the underlying genes have been identified. At present, approximately 10% of all patients do not fall into one of the eight known genetic forms of NCL. We have identified two Asian families with two novel homozygous mutations in the CLN5 gene. In the first Pakistani family, two children developed symptoms of an early juvenile NCL. After exclusion of mutations in genes known to be associated with this age of onset in families from many different countries (CLN1, CLN2, CLN3, CLN6, and CLN8) SNP array-based homozygosity mapping led to the identification of a novel homozygous mutation c.1072-1073delTT (p.Leu358AlafsX4) in CLN5. In the second Afghan family, two children developed symptoms of a late infantile NCL. The mutation c.1137G > T (p.Trp379Cys) in CLN5 was identified. The affected children in these families represent the first reported CLN5 patients originating in Asian sibships. Expression analysis showed that mutant p.Leu358AlafsX4 CLN5 is truncated and lacks a used N-glycosylation at site Asn401. The missense mutation p.Trp379Cys affected neither the size nor glycosylation of the CLN5 protein. Double immunofluorescence microscopy showed that while the wild-type CLN5 protein is localized in lysosomes, both mutant CLN5 proteins are retained in the endoplasmic reticulum rather than reaching the lysosome. doi:10.1016/j.ymgme.2008.11.125
doi:10.1016/j.ymgme.2008.11.123 125. Pompe disease: Egyptian experience with myozyme replacement therapy 123. Construction & characterization of mutation-specific mouse models for Types A and B Niemann–Pick disease
Laila Selim, Zeinab Salah, Ahmed Mency, Cairo University Children Hospitals, Cairo, Egypt
Edward Schuchman, Iwan Jones, Fourogh Katouzian, Mount Sinai School of Medicine, New York, NY, USA
Background: Pompe disease is an autosomal recessive disorder caused by deficiency of the enzyme acid alpha glucosidase (GAA) which results in intralysosomal accumulation of glycogen in multiple organs with prominent involvement of heart and skeletal muscles. The clinical presentation is heterogeneous, largely due to the residual enzyme activity associated with different mutations in the GAA gene, thus it encompasses a range of phenotypes, all of which include varying degrees of myopathy but differ with respect to age of onset, extent of organ involvement and rate of progression to death. The most severe form is the classical infantile_onset disease, described by Pompe with hypertrophic cardiomyopathy, hypotonia, hepatomegaly and death due to cardiorespiratory failure. Methods: A female patient presenting with repeated heart failure and huge cardiomegaly at the age of 3 months, diagnosed by finding deficient acid alpha glucosidase enzyme in leucocytes infantile Pompe disease at the age of 7 months, starts receiving enzyme replacement therapy with myozyme at a rate of 20 mg/kg every 2 weeks for a period of 2 years. Results: Enzyme replacement therapy with acid alpha glucosidase administered to the patient resulted in marked improvement of both the cardiac and skeletal muscles functions (video presentation). Conclusion: Enzyme replacement therapy with acid alpha glucosidase offers hope for patients suffering from this lethal disease.
The currently available mouse model of acid sphingomyelinase (ASM) deficiency (ASMKO) carries a complete knockout of the ASM gene (SMPD1). While these animals have been extremely useful for the assessment of preclinical treatment strategies, they do not express any residual protein and thus cannot be used to evaluate enzyme enhancement approaches. In addition, they develop a rapidly progressive neurological disease, making them a more appropriate model for Type A than Type B NPD. Since all ASM-deficient NPD patients contain point mutations in the SMPD1 gene and express some residual enzymatic activity, we undertook the development of mutation-specific mouse models for this disorder. Two mutations were chosen for these experiments: R496L, a common Type A NPD mutation found in 40% of Ashkenazi Jewish Type A patients, and R608, a common Type B NPD mutation found in 20% of Type B patients from North American and Western Europe. Constructs were generated in which the mutations were introduced into the full-length human SMPD1 cDNA and expression was driven by a fragment derived from the mouse SMPD1 promoter. These constructs were introduced into ASMKO blastocysts, and breeding colonies were generated that express the transgenes on the complete ASMKO background. One founder line for the R496L mutation and three founder lines for the R608 mutation have been established. RNA expression analysis in the brains and livers of these animals revealed that in the R496L line and two of the three R608 lines transgene-derived, SMPD1 RNA expression levels were equivalent to wild-type. In the third R608 line RNA expression levels were significantly below wild-type, but detectable. Notably, using BODIPY-
doi:10.1016/j.ymgme.2008.11.126