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Background: The variants of neuronopathic Gaucher disease may be viewed as a clinical phenotypic continuum divided into acute and chronic forms. The chronic neuronopathic form of Gaucher disease is characterized by a later onset of neurological symptoms and protracted neurological and visceral involvement. The first-choice treatment for nonneuronopathic Gaucher disease is enzyme replacement therapy with recombinant analogues of the deficient human enzyme glucocerebrosidase. Enzyme replacement therapy has been shown to improve hematological and bone manifestations associated with Gaucher disease, but, as with most proteins, recombinant enzymes cannot cross the blood-brain barrier, which prevents effects on neurological manifestations. Substrate reduction therapy with miglustat (N-butyldeoxynojirimycin) inhibits glucosylceramide synthase, which catalyzes the first step in glycosphingolipid synthesis. Because miglustat can cross the blood-brain barrier, it has been suggested that, combined with enzyme replacement therapy, it might be effective in treating neurological symptoms in patients with neuronopathic Gaucher disease., Case Presentation: We report observed effects of combined enzyme replacement therapy and substrate reduction therapy in a 7-year-old Caucasian boy with neuronopathic Gaucher disease who was homozygous for L444P mutations. He had received enzyme replacement therapy from the age of 18 months, and concomitant miglustat treatment was commenced, with dosing according to body surface area uptitrated over 1 month with dietary modifications when he reached the age of 30 months. He experienced mild diarrhea after commencing miglustat therapy, which decreased in frequency/severity over time. His splenomegaly was reduced, and his hematological values and plasma angiotensin-converting enzyme activity normalized. Plasma chitotriosidase also showed substantial and sustained decreases. After 5 years of combination therapy, the patient showed no signs of neurological impairment., Conclusions: This case supports the concept that oral miglustat in combination with intravenous enzyme replacement therapy may be beneficial in preventing neurological signs in patients with chronic neuronopathic Gaucher disease. The importance of dietary modifications has also been confirmed. Further follow-up studies are needed to better define the therapeutic effect of combined treatment in this Gaucher disease subtype.

Lysosomal storage disorders (LSDs) are a heterogeneous group of inborn errors of metabolism caused by inherited deficiencies of any of the lysosomal functions, leading to the accumulation of undegraded substrates in multiple tissues and organs. Two-third of LSDs involves the central nervous system, thus representing the most common cause of pediatric neurodegenerative diseases. Substantial progress has been made in our understanding of the pathophysiology of LSDs, leading to newly targeted therapeutic options. Enzyme replacement therapy (ERT) is currently available for seven LSDs including Gaucher disease, Fabry disease, Pompe disease, and mucopolysaccharidosis (MPS) I (Hurler disease), II (Hunter disease), IV A (Morquio A), and VI (Maroteaux-Lamy disease). ERT reduces lysosomal storage, thus slowing or sometimes avoiding progressive visceral damage altogether. However, ERT is unable to cross the blood-brain barrier (BBB), thus lacking efficacy on neurological manifestations. In patients with MPS I (Hurler disease) under 2 years of age and in selected patients with other LSD, hematopoietic stem cell transplantation is indicated. To bypass the BBB, other approaches, using small molecules are currently being tested and include substrate reduction therapy, which decreases the amount of substrate (currently available for type 1 Gaucher disease and for Niemann-Pick type C disease) and pharmacological chaperones, which enhance the residual activity of the mutant enzyme. [ABSTRACT FROM AUTHOR]

Anderson-Fabry disease (AFD) is an X-linked lysosomal storage disorder caused by mutations in the α-galactosidase A gene on chromosome Xq22, resulting in α-galactosidase A enzyme deficiency. It is characterized by progressive accumulation of lipids (e.g., globotriaosylceramide) in the lysosomes of a variety of cell types, including neural cells. Neurological manifestations, other than cerebrovascular accidents, include small fiber neuropathy and dysautonomic disorders. Small fiber peripheral neuropathy often is clinically manifested at young ages. Peripheral pain can be chronic and/or can occur as provoked attacks of excruciating pain. Manifestations of dysfunction of small autonomic fibers may include impaired sweating, gastrointestinal dysmotility, and abnormal pain perception. Patients with AFD often remain undiagnosed until the emergence of a more typical clinical manifestation, characterized by chronic renal and cardiac failure. Early clinical benefits of enzyme replacement therapy include reduction of neuropathic pain, and adequate management of residual pain to a tolerable and functional level, which can substantially improve the quality of these patients. Thus, it is important that physicians consider AFD in the differential diagnosis of neurological manifestations to provide an appropriate diagnostic and therapeutic workup. [ABSTRACT FROM AUTHOR]