Gaucher Disease: Our primary interest is to understand the pathogenesis of the neurological involvement in this disease and to test novel therapeutic approaches. We are conducting a randomized controlled trial of OGT 918 (N-butyldeoxynojirimycin, miglustat) as a substrate reduction approach for the treatment of patients with neuronopathic Gaucher disease. We are evaluating primarily the neurological abnormalities, and in particular the slow eye movements of these patients. Thus far, this medication is well tolerated. Results of the 1st year did not show any significant difference between the group on OGT 918 and the group. Final results of this two-year study will be available in FY 2007. We showed for the first time that electron microscopy study of the skin could identify patients with type 2 (acute neuronopathic) Gaucher disease. This finding will enable early diagnosis and institution of appropriate therapy to this devastating form of the disease. Over the past year in collaboration with Dr. Ellen Sidransky we further characterized a large cohort of patients with type 3 (chronic neuronopathic) Gaucher disease. We showed that patients homozygous for the most common neuronopathic mutation have a wide variety of phenotypes. This finding emphasizes the role of genetic modifiers in this disorder. On the other hand, we showed that different mutations could lead to the same phenotype - progressive myoclonic encephalopathy.? ? Fabry Disease: Patients with this second most common lysosomal disorder have a severely painful peripheral neuropathy, and a systemic vasculopathy leading to premature strokes, cardiac disease, and kidney insufficiency. We have been exploring enzyme replacement therapy (ERT) for Fabry disease. Patients on long-term therapy had significant reduction in pain, improvement in sensing cold and warm and in their sweat function. However, ERT did not reduce the incidence of stroke. We therefore performed extensive studies on the pathogenesis of stroke in Fabry disease. Our ongoing hypothesis regarding strokes this disorder is that reactive oxygen species play an important role. We found increased staining for 3-nitrotyrosine in dermal and cerebral blood vessels and elevated nitrotyrosine and myeloperoxidase levels in blood of patients. Myeloperoxidase elevation may be related to our observation of premature atherosclerosis in patients with Fabry disease, a finding confirmed by another group in a mouse model for this disorder. We found that the likelihood of occurrence of cerebral lesions seen on MRI in patients with Fabry disease seems to be modified by alterations of other genetic risk factors for stroke such as interleukin-6, factor V Leiden, protein Z and endothelial nitric oxide synthase. This year we also found that random myeloperoxidase in serum and plasma was significantly elevated in 73 consecutive male patients with Fabry disease. Random serum myeloperoxidase level in men predicted the risk of a Fabry vasculopathy-related event in subsequent years. Long-term enzyme replacement therapy did not reduce myeloperoxidase level or eliminate the risk of vasculopathic events. These observations should contribute to the general understanding of Fabry disease and vasculopathies of the general population. Because of the partial effect of ERT in adult patients, we hypothesized that better results may be obtained when it is initiated in childhood. We therefore completed a 6-month study on ERT in children 7-17 years of age with Fabry disease. We found that ERT was safe, led to improved cardiac, renal and sweat function and lessening of neuropathic pain. This study is continuing in order to determine the long-term effect of ERT in this patient population. Using genomic techniques, we found that neuronal apoptosis inhibitor protein is over-expressed in children with Fabry disease. This finding should help understand the pathogenesis of this disease and serve as a potential marker to monitor response to specific therapies. Using state-of-the-art proteomics techniques, and taking advantage of the specific effects of ERT, we found decreased alpha2-antiplasmin and plasminogen in the blood of patients with Fabry disease. This finding likely indicates a general abnormality in fibrinolysis in this disorder. We completed a genomics study in the mouse model of Fabry disease. We examined the heart, liver and aorta of male Fabry knockout mice 28 weeks of age compared with wild-type mice. Gene expression analyses were performed using microarrays before and after six weekly injections of alpha-galactosidase A. RPGRIP1 was the highest ranked statistically in all 3 organs and its splice variants responded in a unique way to alpha-galactosidase A. ERT tended to not only normalize gene expression, but also specifically modified gene expression in each tissue. We then looked at the data using gene expression correlation graphs as well as structural equation modeling and path analysis. This method allowed us to generate statistical hypotheses regarding mechanisms of disease that will be tested in the laboratory in the future. We initiated a program of active-site chaperone therapy in patients with Fabry disease who have with enhanceable alpha-galactosidase A activity. Work in our laboratory confirmed marked in vitro enhanceability of the deficient enzyme in peripheral blood white cells of some patients by the chemical chaperone. A treatment trial is ongoing in patients with Fabry disease and initial results are promising. The extensive delivery throughout the body of chemical chaperones should have a significant advantage over ERT where the infused enzyme enters into vascular endothelial cells for the most part. This therapeutic approach should be applicable to other disorders where the mutated enzyme is enhanceable. ? ? Mucolipidosis IV: We continued our investigation of 35 patients with this autosomal recessive neurogenetic disorder with particular emphasis on their progressive retinal degeneration. The latter is thought to be caused by death of neurons in the retina. Using electroretinography and visual evoked potential we quantified the decline of retinal function in MLIV. This study will be useful to identify the optimal stage for therapeutic intervention to prevent progression of the retinal dystrophy in MLIV. The neurological aspect of this disorder is developmental in nature with little decline over the years. It is therefore evident that mucolipidosis IV is both a developmental and a degenerative disorder. The presentation as a cerebral palsy-like encephalopathy often delays the correct diagnosis of this condition. ? ? Leukodystrophies: We continued studying patients with leukodystrophies including the fatal leukodystrophy CACH (childhood ataxia with CNS hypomyelination), a leukodystrophy that was first identified by DMNB in 1992. It is caused by a deficiency of eukaryotic initiation factor 2B (eIF2B). The clinical decline is often initiated or worsens after stress such as a mild head trauma or a febrile illness. eIF2B is a protein complex that is essential for the regulation of protein synthesis, particularly in response to stress. Over the past year we continued collaboration on a finding that patients with eIF2B mutations have marked decrease of asialo-transferrin in the cerebrospinal fluid. This finding was confirmed in a blinded analysis and was found to have 100% and 98% specificity. The reduction of asialo-transferrin likely reflects disturbance in the function of oligodendrocytes and astrocytes and will help with diagnosis and disease management. We also identified a novel leukodystrophy syndrome consisting of hypomyelination, hypogonadotropic hypogonadism and hypodontia (termed 4H syndrome). Electron microscopy and myelin protein immunohistochemistry of sural nerve showed unique findings.
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