Lysosomal storage disorders are a broad group of diseases composed of a variety of sub-groups of disorders, such as the mucopolysaccharidoses, the glycoproteinoses, and the sphingolipidoses. A lysosomal storage disease can present in a number of different ways. Infants or children may have growth failure, developmental regression, corneal or lens clouding, hepato- and/or splenomegaly, coarsening facial features and skeletal abnormalities. Some disorders are more likely to have a neurological presentation or present in adults. While a diverse group, different storage diseases may have similar clinical features, thus it may be necessary to measure a number of different enzyme activities prior to finding the one deficient in a particular patient.