[Biochemical diagnosis and enzymic diagnosis of lysosomal diseases]

Originally, diagnosis of lysosomal diseases was primarily based on clinicopathological findings and on identification of abnormally stored substances by analytical biochemistry. Since extraneural tissues possess only very low levels of sphingolipids, lipid analysis with Folch method and/or its modifications is usually limited to nervous system, and their applicability is restricted to postmortem examination and, occasionally, to verification of a prenatal diagnosis after abortion. On the other hand, recently developed TLC/enzyme immunostaining method might be useful for antemortem analysis of abnormally stored glycosphingolipids, because it could detect glycosphingolipids quantitatively with clinically available 0.5 approximately 1 ml CSF. During the past two decades, however, diagnostic emphasis has shifted to enzymic assay, which provide relatively easy, noninvasive antemortem diagnosis because clinically available enzyme sources, such as serum, leukocytes and cultured fibroblasts, and also commercially available artificial substrates can be used. These procedures can be used to detect heterozygous carriers. Identification of affected fetus during early pregnancy is generally possible with similar procedures.