Lysosomal Storage Disorders

The lysosomal storage disorders (LSDs) are a group of inborn organelle disorders, clinically heterogeneous, and biochemically characterized by accumulation of nondegraded macromolecules primarily in the lysosomal and other cellular compartments. Given the common and essential cellular function of the lysosomal system in different organs and systems, patients afflicted with these disorders present a broad range of clinical problems, including neurological problems, visceromegaly, and skeletal deformities. Onset of symptoms may range from fetal period to adulthood. The neurological problems include developmental delay, seizures, acroparesthesia, motor weakness, muscle wasting, behavioral/psychiatric disturbances, cerebrovascular ischemic events, and extrapyramidal signs. Patients may present with symptoms later that include psychiatric manifestations, are slowly progressive, and may precede other neurologic or systemic features. Most of LSDs are autosomal recessive; however, a few are X-linked with symptpmatic female carriers (e.g., Fabry disease). In most of them, the diagnosis is established by biochemical and/or molecular assays. In terms of management, disease-modifying therapies include enzyme replacement, hematopoietic stem cell transplantation, and substrate reduction therapy. Patients and their families require genetic counseling regarding reproductive risks, disease prognosis, and therapeutic options. Investigations of disease molecular mechanisms provide insights into potential targets for the development of therapeutic strategies. Supportive care has been the key and essential for most LSDs, resulting in substantial improvement in quality of life of patients and families.