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 18.104.22.168), 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.
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.
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