Gaucher disease, a lysosomal storage disease, is an autosomal recessive condition caused by beta-glucocerebrosidase deficiency resulting in progressive accumulation of glucosylceramide in the lysosomes. Gaucher disease represents a continuous clinical spectrum that may be classified based on involvement of the central nervous system: Type I typically manifests in childhood with hepatosplenomegaly, anemia and thrombocytopenia, lung disease, bone disease, and the absence of primary central nervous system disease. Severity and age of onset vary widely. Type II is an acute neuronopathic form, of which the severe form is lethal perinatally. Type II usually presents in infancy and is often fatal by 2-4 years of age. Neurologic deterioration is rapid and involves cranial nerves as well as the extrapyramidal tract. There is little psychomotor development. Type III (subacutely neuronopathic) is differentiated into Type IIIA (myoclonus, dementia), IIIB (isolated horizontal supranuclear gaze palsy), and IIIC (cardiovascular calcifications of the aortic and mitral valves, mild splenomegaly, corneal opacities, and supra nuclear ophthalmoplegia). Type III may present before 2 years of age, but progresses more slowly than type II with individuals living into their third or fourth decades. This laboratory performs Sanger sequencing of the GBA gene.