- Email: [email protected]
74 Development of a filter paper method applicable to a mass urinary screening for Fabry disease
Abstracts / Molecular Genetics and Metabolism 92 (2007) S11–S34 on mobility. Pulmonary function vital capacity increased from 0.72 prior to treatment to 1.5 after two years of enzyme therapy. The patient has experienced no adverse events since beginning enzyme replacement therapy. Infantile-onset Pompe disease is a progressive and eventually lethal muscle disorder. Enzyme replacement therapy in our patient has both stopped and reversed the muscle disorder as witnessed by improvements in pulmonary function testing, muscle stamina studies, and observed endurance. doi:10.1016/j.ymgme.2007.08.074
70 Enhanced response to enzyme replacement therapy in Pompe disease following the induction of immune tolerance Dwight D. Koeberl a, Baodong Sun b, Andrew Bird b, Sarah P. Young b, Y.-T. Chen b, Priya S. Kishnani b, a Duke University Medical Center, Durham, NC, USA, b Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA Pompe disease (MIM 232300), the deficiency of acid alpha-glucosidase (GAA; acid maltase; EC 3.2.1.20), causes death in early childhood related to glycogen accumulation in striated muscle and an accompanying cardiomyopathy. The efficacy of enzyme replacement therapy (ERT) with recombinant human GAA (hGAA) was demonstrated during clinical trials that prolonged subjects’ ventilator-free survival and led to broad label FDA approval. Unfortunately CRIM-negative Pompe subjects, who lack any residual GAA expression, respond poorly to ERT. CRIM-negative subjects typically became ventilator-dependent and the majority did not survive beyond a median age of 32 months. The limited efficacy of ERT for CRIM-negative Pompe patients has motivated efforts to develop gene therapy in the GAA-knockout (GAA-KO) mouse model. Gene therapy with an adeno-associated virus (AAV) vector containing a liver-specific promoter elevated the plasma GAA activity in plasma and prevented anti-GAA antibody formation in immunocompetent GAA-KO mice for 18 weeks, suggesting that immune tolerance to hGAA had been achieved. We predicted that liver-specific expression of hGAA with the AAV vector would induce immune tolerance and enhance the efficacy of ERT. A very low number of AAV vector particles was administered prior to initiation of ERT to prevent the antibody response in GAA-KO mice. A robust antibody response was provoked in naı¨ve GAA-KO mice by a challenge with hGAA and Freund’s reagent; in contrast, administration of the AAV vector prior to the hGAA challenge prevented the antibody response. Most compellingly, the antibody response to ERT was ameliorated for 12 weeks by prior AAV vector administration, and the efficacy of ERT was thereby enhanced. Thus, AAV-vector mediated gene therapy induced tolerance to introduced hGAA, and this strategy could enhance the efficacy of ERT in CRIM-negative Pompe disease patients and in other lysosomal storage diseases.
S27
and pulmonary disease to progressive neurodegenerations that may present from childhood through later adult life. Because the deficient gene product in the majority of patients (the NPC1 protein) is not transducible, replacement strategies are not an option. Therapeutic attention has necessarily been focused on downstream interventions; a clinical trial is currently in progress using an iminosugar to inhibit glucosylceramide synthase. The current trial has highlighted challenges in mounting such studies for most LSDs, including the absence of robust natural history data, a limited pool of suitable candidates for such studies and a paucity of surrogate and biomarkers. Preclinical investigations of strategies involving replacement of a deficient neurosteroid and overexpression of specific Rabs are yielding promising results. Current data suggest that in the short to medium term, combined therapies to interdict downstream pathways are most likely to favorably modify the course of NPC, and by extension, other LSDs in which transduction strategies are either impractical or imperfect in correcting the phenotype. doi:10.1016/j.ymgme.2007.08.076
73 Sleeping Beauty transposon-mediated correction of mucopolysaccharidosis type I Elena Aronovich a, Jason B. Bell b, Lalitha R. Belur b, a University of Minnesota, Minneapolis, MN, USA, b Department of Genetics, Cell Biology and Development and Arnold and Mabel Beckman Center for Transposon Research We evaluated the Sleeping Beauty transposon system (SBTS) for delivery of the human alfa-L-iduronidase (hIDUA) gene to livers of IDUA-deficient mice. Plasma IDUA activities reached >100-fold of wild-type levels a day after hydrodynamic injection, but were essentially gone by 4 weeks. The near-simultaneous loss of the hIDUA transgene, its expression and the plasmid out of which hIDUA transposons transposed suggested induction of an immune response against hIDUA-expressing cells. To analyze the contribution of a cell-mediated immune response to the clearance of liver cells expressing hIDUA, we administered either of two transposon vectors that expressed either luciferase (Luc), a protein confined to the cytoplasm, or hIDUA, which can escape from the cell and thereby elicit a strong immune response. Mouse livers were analyzed over time for cellular infiltrates, including CD4+ and CD8+ lymphocytes. We found stronger immune responses in the livers of hIDUA-treated mice than in Luc-treated mice. Accordingly, we treated IDUA-deficient mice with cyclophosphomide, an immune-suppressing drug, before administering the hIDUA transposons. Plasma IDUA activities dropped more than 100-fold by 2 weeks but then persisted for over 3 months at up to 100-fold WT activity in one third of the mice treated with the full transposon system. These persistent IDUA activity levels were sufficient to completely reverse lysosomal pathology in the liver and partially in distant organs. Thus, we have demonstrated feasibility of reversing Mucopolysaccharidosis Type I disease in adult mice with a single dose of the SBTS.
doi:10.1016/j.ymgme.2007.08.075 doi:10.1016/j.ymgme.2007.08.078
71 Niemann-Pick disease, type C: A model for pathophysiology and management of LSDs Marc Patterson, Columbia University Medical Center, New York, NY, USA, Weill Medical College of Cornell University Niemann-Pick disease, type C (NPC) is an unconventional lysosomal storage disease caused by mutations in two genes whose products are critical for endosomal–lysosomal trafficking of macromolecules, in contrast to deficiency of a lysosomal hydrolase that originally defined these disorders. The lysosomal sequestration of a variety of lipids is associated with accelerated apoptosis and neuronal loss in a unique striated pattern in the cerebellum, inflammation and abnormal calcium homeostasis. The clinical phenotypes are protean, ranging from fetal and neonatal onset hepatic
74 Development of a filter paper method applicable to a mass urinary screening for Fabry disease Christiane Auray-Blais, Denis Cyr, Robert Gigue`re, Bernard Lemieux, Re´gen Drouin, Universite´ de Sherbrooke, Sherbrooke, Que., Canada It is difficult to establish the incidence of patients with Fabry disease considering that the clinical presentation is very heterogeneous, several atypical variants exist and heterozygotes are afflicted with symptoms varying in severity. Screening newborn babies for lysosomal storage disorders (LSDs) emerges from a worldwide scientific and clinical consensus to the effect that early detection of patients leads to rapid therapeutic intervention (where available) and prevents the onset of severe and irreversible
S28
Abstracts / Molecular Genetics and Metabolism 92 (2007) S11–S34
clinical manifestations. We opted for the development of a biomarker filter paper method because in our Screening Program, newborn urine samples are collected by the parents on filter papers at 21 days of age. With technological advancements such as liquid chromatography-tandem mass spectrometry (LC–MS/MS), it is now feasible to analyze large molecules for treatable LSDs, such as globotriaosylceramide (GL-3) for Fabry disease. Total GL-3 analyses were carried out by positive electrospray ionization using a Waters Micromass Quattro micro tandem quadrupole system equipped with an Alliance 2795XE LC, while working with a two-step ammonium acetate-formic acid gradient. Validation (linearity, limit of detection and quantification, recovery) of the LC–MS/MS method was performed and the stability of GL-3 on filter paper established under different temperature conditions during 7 weeks (IS: C17:0-GL-3 isoform). This filter paper method eliminates lipid extraction, glycolipid isolation, centrifugation and evaporation steps. It is rapid, specific and highly sensitive for the analysis of total GL-3 isoforms, applicable to a forthcoming feasibility study. doi:10.1016/j.ymgme.2007.08.079
such as hematopoietic stem cell transplant and enzyme replacement therapy will affect long term outcomes. Second, age at which the treatment is applied will likely make a significant difference in outcome. Third, premorbid health status including orthopedic, sensory, central nervous system, and psychological status. Fourth, biomedical factors such as genotype, enzyme levels, and GAG levels. Finally, environmental factors such as psychological environment of the child, parental expectations, and life events may impact QOL, adaptive status, and psychosocial adjustment. We plan to measure QOL using various measures. The health outcome indices pilot study is to develop an objective rating of physician or health professional’s reported health status that can be used to assess the progress in several domains of functioning. The long term goal will be to correlate this with the parent and child’s rated quality-of-life. The measurement of children’s health outcomes and quality-of-life has assumed increased importance to determine whether the benefits accrued to the child after treatment sufficiently outweigh the risks, to analyze the factors contributing to benefits and risk to include the parent and child perception of whether a positive quality-of-life has been attained, and to study to factors contributing to health related quality-of-life and ways to improve it. doi:10.1016/j.ymgme.2007.08.081
75 The hunter outcome survey (HOS): A registry of mucopolysaccharidosis II patients Michael Beck, for the HOS Medical Advisory BoardChildrens Hospital University of Mainz, Mainz, Rhineland-Palatinat, Germany Mucopolysaccharidosis II (MPS II, Hunter syndrome) is a rare, progressive, X-linked disorder of glycosaminoglycan (GAG) metabolism that results in progressive GAG accumulation within multiple tissues and organs, due to a deficiency of iduronate-2-sulfatase (I2S). Idursulfase, a recombinant human I2S, is being developed as a treatment for MPS II. The Hunter Outcome Survey (HOS) is a global patient registry of MPS II patients sponsored by Shire Human Genetic Therapies, Inc. All MPS II patients are eligible regardless of treatment. The objectives of HOS are to enhance our understanding of the natural history of MPS II, to monitor the safety and efficacy of enzyme replacement therapy, and to provide the basis for the development of clinical management guidelines. The HOS database will capture clinical information obtained during the routine follow-up of MPS II patients, and these data will be transmitted electronically to the central database. HOS will benefit participating physicians by providing them with the opportunity to contribute to the study of the management of MPS II and by giving them the ability to review data on a larger population of MPS II patients. As of June 2006, over 60 patients from 15 sites in 7 countries have been enrolled into HOS. As enrollment increases, HOS will improve our understanding of MPS II, the long-term impact of enzyme replacement therapy and allow the development of evidence based clinical management guidelines. doi:10.1016/j.ymgme.2007.08.080
76 Quality-of-life and psychosocial outcomes in patients with MPS disorders who have undergone hematopoietic stem cell transplant Kendra Bjoraker, Elsa G. Shapiro, Lawrence Charnas, Paul Orchard, Kathleen Delaney, Cheryl K. Johnson, University of Minnesota, Minneapolis, MN, USA Advances in medical treatment have prolonged the lives of children with mucopolysaccharidosis (MPS I) and have necessitated increased attention to the assessment of their functioning and adaptation. Qualityof-life, adaptive skills, and psychosocial outcomes have not been systematically studied in children with MPS I. Our goal is to assess the factors that influence health outcomes and the quality-of-life, adaptive skills, and psychosocial adjustment in the developing child with MPS I, treated and untreated. Psychosocial adjustment, adaptive skills, and QOL are influenced by a number of factors. First, treatments and their side effects,
78 Mucolipidoses II and III: Clinical and molecular characterization Sara Cathey a, Michael Friez b, Karisa Draper b, Jules Leroy b, a Greenwood Genetic Center, Greenwood, SC, USA, b Ghent University Hospital, Department of Medical Genetics, Belgium Background: Mucolipidosis II and mucolipidosis III are allelic disorders of lysosomal enzyme targeting due to deficiency of GlcNAc-phosphotransferase. This alpha-2/beta-2/gamma-2 hexamer is encoded by two genes. The alpha and beta subunits are encoded by GNPTA, and the gamma subunit is encoded by GNPTG. Prior to molecular testing, ML II was distinguished from ML III by the severity of the clinical course. The goals of this project are to genotype individuals with clinical ML II or ML III and make genotype–phenotype correlations. Methods: Molecular analyses, which include sequencing the 21 exons of GNPTA in ML II and ML III probands and targeted sequencing in parents, have been completed in 29 of 40 participating families. Clinical data are obtained from medical records, questionnaire completed by parents of affected children, and physical exam when feasible. Results: Pathogenic changes have been found in GNPTA in every family. No mutations have been found in GNPTG. Patients with the most severe phenotype and clinical ML II have homozygous frameshifts, two different frameshifts, or one frameshift and one nonsense mutation. These patients have evidence of growth retardation at birth, dysmorphic features, and significant development delays. Individuals with clinical ML III have one missense or splice mutation with one frameshift. These individuals may not be diagnosed until mid-childhood, and limited joint mobility is often the presenting problem. Individuals ML II/III have mixed genotypes and phenotypes. doi:10.1016/j.ymgme.2007.08.083
79 Type II perinatal lethal Gaucher disease: Identification of a novel mutation, P332L, in a case study from Vancouver Island, British Columbia, Canada Francis Choy a, Agnes Zay b, Patrick MacLeod c, Cherrie R. Tan-Dy d, a University of Victoria, Victoria, BC, Canada, b Biology Department, UVic, c Division of Medical Genetics, d Department of Pediatrics, Victoria General Hospital, Victoria, BC, Canada Gaucher disease (GD) is the most prevalent lysosomal storage disorder and results from an inherited deficiency of the enzyme glucocerebrosidase. Three clinical forms of Gaucher disease have been described: Type 1, non-
70 Enhanced response to enzyme replacement therapy in Pompe disease following the induction of immune tolerance Dwight D. Koeberl a, Baodong Sun b, Andrew Bird b, Sarah P. Young b, Y.-T. Chen b, Priya S. Kishnani b, a Duke University Medical Center, Durham, NC, USA, b Division of Medical Genetics, Department of Pediatrics, Duke University Medical Center, Durham, NC, USA Pompe disease (MIM 232300), the deficiency of acid alpha-glucosidase (GAA; acid maltase; EC 3.2.1.20), causes death in early childhood related to glycogen accumulation in striated muscle and an accompanying cardiomyopathy. The efficacy of enzyme replacement therapy (ERT) with recombinant human GAA (hGAA) was demonstrated during clinical trials that prolonged subjects’ ventilator-free survival and led to broad label FDA approval. Unfortunately CRIM-negative Pompe subjects, who lack any residual GAA expression, respond poorly to ERT. CRIM-negative subjects typically became ventilator-dependent and the majority did not survive beyond a median age of 32 months. The limited efficacy of ERT for CRIM-negative Pompe patients has motivated efforts to develop gene therapy in the GAA-knockout (GAA-KO) mouse model. Gene therapy with an adeno-associated virus (AAV) vector containing a liver-specific promoter elevated the plasma GAA activity in plasma and prevented anti-GAA antibody formation in immunocompetent GAA-KO mice for 18 weeks, suggesting that immune tolerance to hGAA had been achieved. We predicted that liver-specific expression of hGAA with the AAV vector would induce immune tolerance and enhance the efficacy of ERT. A very low number of AAV vector particles was administered prior to initiation of ERT to prevent the antibody response in GAA-KO mice. A robust antibody response was provoked in naı¨ve GAA-KO mice by a challenge with hGAA and Freund’s reagent; in contrast, administration of the AAV vector prior to the hGAA challenge prevented the antibody response. Most compellingly, the antibody response to ERT was ameliorated for 12 weeks by prior AAV vector administration, and the efficacy of ERT was thereby enhanced. Thus, AAV-vector mediated gene therapy induced tolerance to introduced hGAA, and this strategy could enhance the efficacy of ERT in CRIM-negative Pompe disease patients and in other lysosomal storage diseases.
S27
and pulmonary disease to progressive neurodegenerations that may present from childhood through later adult life. Because the deficient gene product in the majority of patients (the NPC1 protein) is not transducible, replacement strategies are not an option. Therapeutic attention has necessarily been focused on downstream interventions; a clinical trial is currently in progress using an iminosugar to inhibit glucosylceramide synthase. The current trial has highlighted challenges in mounting such studies for most LSDs, including the absence of robust natural history data, a limited pool of suitable candidates for such studies and a paucity of surrogate and biomarkers. Preclinical investigations of strategies involving replacement of a deficient neurosteroid and overexpression of specific Rabs are yielding promising results. Current data suggest that in the short to medium term, combined therapies to interdict downstream pathways are most likely to favorably modify the course of NPC, and by extension, other LSDs in which transduction strategies are either impractical or imperfect in correcting the phenotype. doi:10.1016/j.ymgme.2007.08.076
73 Sleeping Beauty transposon-mediated correction of mucopolysaccharidosis type I Elena Aronovich a, Jason B. Bell b, Lalitha R. Belur b, a University of Minnesota, Minneapolis, MN, USA, b Department of Genetics, Cell Biology and Development and Arnold and Mabel Beckman Center for Transposon Research We evaluated the Sleeping Beauty transposon system (SBTS) for delivery of the human alfa-L-iduronidase (hIDUA) gene to livers of IDUA-deficient mice. Plasma IDUA activities reached >100-fold of wild-type levels a day after hydrodynamic injection, but were essentially gone by 4 weeks. The near-simultaneous loss of the hIDUA transgene, its expression and the plasmid out of which hIDUA transposons transposed suggested induction of an immune response against hIDUA-expressing cells. To analyze the contribution of a cell-mediated immune response to the clearance of liver cells expressing hIDUA, we administered either of two transposon vectors that expressed either luciferase (Luc), a protein confined to the cytoplasm, or hIDUA, which can escape from the cell and thereby elicit a strong immune response. Mouse livers were analyzed over time for cellular infiltrates, including CD4+ and CD8+ lymphocytes. We found stronger immune responses in the livers of hIDUA-treated mice than in Luc-treated mice. Accordingly, we treated IDUA-deficient mice with cyclophosphomide, an immune-suppressing drug, before administering the hIDUA transposons. Plasma IDUA activities dropped more than 100-fold by 2 weeks but then persisted for over 3 months at up to 100-fold WT activity in one third of the mice treated with the full transposon system. These persistent IDUA activity levels were sufficient to completely reverse lysosomal pathology in the liver and partially in distant organs. Thus, we have demonstrated feasibility of reversing Mucopolysaccharidosis Type I disease in adult mice with a single dose of the SBTS.
doi:10.1016/j.ymgme.2007.08.075 doi:10.1016/j.ymgme.2007.08.078
71 Niemann-Pick disease, type C: A model for pathophysiology and management of LSDs Marc Patterson, Columbia University Medical Center, New York, NY, USA, Weill Medical College of Cornell University Niemann-Pick disease, type C (NPC) is an unconventional lysosomal storage disease caused by mutations in two genes whose products are critical for endosomal–lysosomal trafficking of macromolecules, in contrast to deficiency of a lysosomal hydrolase that originally defined these disorders. The lysosomal sequestration of a variety of lipids is associated with accelerated apoptosis and neuronal loss in a unique striated pattern in the cerebellum, inflammation and abnormal calcium homeostasis. The clinical phenotypes are protean, ranging from fetal and neonatal onset hepatic
74 Development of a filter paper method applicable to a mass urinary screening for Fabry disease Christiane Auray-Blais, Denis Cyr, Robert Gigue`re, Bernard Lemieux, Re´gen Drouin, Universite´ de Sherbrooke, Sherbrooke, Que., Canada It is difficult to establish the incidence of patients with Fabry disease considering that the clinical presentation is very heterogeneous, several atypical variants exist and heterozygotes are afflicted with symptoms varying in severity. Screening newborn babies for lysosomal storage disorders (LSDs) emerges from a worldwide scientific and clinical consensus to the effect that early detection of patients leads to rapid therapeutic intervention (where available) and prevents the onset of severe and irreversible
S28
Abstracts / Molecular Genetics and Metabolism 92 (2007) S11–S34
clinical manifestations. We opted for the development of a biomarker filter paper method because in our Screening Program, newborn urine samples are collected by the parents on filter papers at 21 days of age. With technological advancements such as liquid chromatography-tandem mass spectrometry (LC–MS/MS), it is now feasible to analyze large molecules for treatable LSDs, such as globotriaosylceramide (GL-3) for Fabry disease. Total GL-3 analyses were carried out by positive electrospray ionization using a Waters Micromass Quattro micro tandem quadrupole system equipped with an Alliance 2795XE LC, while working with a two-step ammonium acetate-formic acid gradient. Validation (linearity, limit of detection and quantification, recovery) of the LC–MS/MS method was performed and the stability of GL-3 on filter paper established under different temperature conditions during 7 weeks (IS: C17:0-GL-3 isoform). This filter paper method eliminates lipid extraction, glycolipid isolation, centrifugation and evaporation steps. It is rapid, specific and highly sensitive for the analysis of total GL-3 isoforms, applicable to a forthcoming feasibility study. doi:10.1016/j.ymgme.2007.08.079
such as hematopoietic stem cell transplant and enzyme replacement therapy will affect long term outcomes. Second, age at which the treatment is applied will likely make a significant difference in outcome. Third, premorbid health status including orthopedic, sensory, central nervous system, and psychological status. Fourth, biomedical factors such as genotype, enzyme levels, and GAG levels. Finally, environmental factors such as psychological environment of the child, parental expectations, and life events may impact QOL, adaptive status, and psychosocial adjustment. We plan to measure QOL using various measures. The health outcome indices pilot study is to develop an objective rating of physician or health professional’s reported health status that can be used to assess the progress in several domains of functioning. The long term goal will be to correlate this with the parent and child’s rated quality-of-life. The measurement of children’s health outcomes and quality-of-life has assumed increased importance to determine whether the benefits accrued to the child after treatment sufficiently outweigh the risks, to analyze the factors contributing to benefits and risk to include the parent and child perception of whether a positive quality-of-life has been attained, and to study to factors contributing to health related quality-of-life and ways to improve it. doi:10.1016/j.ymgme.2007.08.081
75 The hunter outcome survey (HOS): A registry of mucopolysaccharidosis II patients Michael Beck, for the HOS Medical Advisory BoardChildrens Hospital University of Mainz, Mainz, Rhineland-Palatinat, Germany Mucopolysaccharidosis II (MPS II, Hunter syndrome) is a rare, progressive, X-linked disorder of glycosaminoglycan (GAG) metabolism that results in progressive GAG accumulation within multiple tissues and organs, due to a deficiency of iduronate-2-sulfatase (I2S). Idursulfase, a recombinant human I2S, is being developed as a treatment for MPS II. The Hunter Outcome Survey (HOS) is a global patient registry of MPS II patients sponsored by Shire Human Genetic Therapies, Inc. All MPS II patients are eligible regardless of treatment. The objectives of HOS are to enhance our understanding of the natural history of MPS II, to monitor the safety and efficacy of enzyme replacement therapy, and to provide the basis for the development of clinical management guidelines. The HOS database will capture clinical information obtained during the routine follow-up of MPS II patients, and these data will be transmitted electronically to the central database. HOS will benefit participating physicians by providing them with the opportunity to contribute to the study of the management of MPS II and by giving them the ability to review data on a larger population of MPS II patients. As of June 2006, over 60 patients from 15 sites in 7 countries have been enrolled into HOS. As enrollment increases, HOS will improve our understanding of MPS II, the long-term impact of enzyme replacement therapy and allow the development of evidence based clinical management guidelines. doi:10.1016/j.ymgme.2007.08.080
76 Quality-of-life and psychosocial outcomes in patients with MPS disorders who have undergone hematopoietic stem cell transplant Kendra Bjoraker, Elsa G. Shapiro, Lawrence Charnas, Paul Orchard, Kathleen Delaney, Cheryl K. Johnson, University of Minnesota, Minneapolis, MN, USA Advances in medical treatment have prolonged the lives of children with mucopolysaccharidosis (MPS I) and have necessitated increased attention to the assessment of their functioning and adaptation. Qualityof-life, adaptive skills, and psychosocial outcomes have not been systematically studied in children with MPS I. Our goal is to assess the factors that influence health outcomes and the quality-of-life, adaptive skills, and psychosocial adjustment in the developing child with MPS I, treated and untreated. Psychosocial adjustment, adaptive skills, and QOL are influenced by a number of factors. First, treatments and their side effects,
78 Mucolipidoses II and III: Clinical and molecular characterization Sara Cathey a, Michael Friez b, Karisa Draper b, Jules Leroy b, a Greenwood Genetic Center, Greenwood, SC, USA, b Ghent University Hospital, Department of Medical Genetics, Belgium Background: Mucolipidosis II and mucolipidosis III are allelic disorders of lysosomal enzyme targeting due to deficiency of GlcNAc-phosphotransferase. This alpha-2/beta-2/gamma-2 hexamer is encoded by two genes. The alpha and beta subunits are encoded by GNPTA, and the gamma subunit is encoded by GNPTG. Prior to molecular testing, ML II was distinguished from ML III by the severity of the clinical course. The goals of this project are to genotype individuals with clinical ML II or ML III and make genotype–phenotype correlations. Methods: Molecular analyses, which include sequencing the 21 exons of GNPTA in ML II and ML III probands and targeted sequencing in parents, have been completed in 29 of 40 participating families. Clinical data are obtained from medical records, questionnaire completed by parents of affected children, and physical exam when feasible. Results: Pathogenic changes have been found in GNPTA in every family. No mutations have been found in GNPTG. Patients with the most severe phenotype and clinical ML II have homozygous frameshifts, two different frameshifts, or one frameshift and one nonsense mutation. These patients have evidence of growth retardation at birth, dysmorphic features, and significant development delays. Individuals with clinical ML III have one missense or splice mutation with one frameshift. These individuals may not be diagnosed until mid-childhood, and limited joint mobility is often the presenting problem. Individuals ML II/III have mixed genotypes and phenotypes. doi:10.1016/j.ymgme.2007.08.083
79 Type II perinatal lethal Gaucher disease: Identification of a novel mutation, P332L, in a case study from Vancouver Island, British Columbia, Canada Francis Choy a, Agnes Zay b, Patrick MacLeod c, Cherrie R. Tan-Dy d, a University of Victoria, Victoria, BC, Canada, b Biology Department, UVic, c Division of Medical Genetics, d Department of Pediatrics, Victoria General Hospital, Victoria, BC, Canada Gaucher disease (GD) is the most prevalent lysosomal storage disorder and results from an inherited deficiency of the enzyme glucocerebrosidase. Three clinical forms of Gaucher disease have been described: Type 1, non-