Laboratory studies of inherited metabolic disorders: Lysosome storage diseases

Inborn errors of metabolism (IEM) display very diverse clinical symptoms, ranging from very mild to incompatible with life. The clinical heterogeneity may complicate diagnosis of these rare diseases. Recent advances in diagnosis as well as treatment of IEM have improved the prognosis for patients with IEM considerably and necessitate an update of knowledge on these disorders among pediatricians. To facilitate prompt and accurate diagnosis of IEM, expert analyses of (1) metabolites in blood and urine, (2) enzyme levels in blood cells, cultured fibroblasts or tissues, and (3) genetic defects are required. This paper illustrates several aspects of these three categories of laboratory diagnostics and emphasizes the need to share information, not only between doctor and laboratory, but also between the different laboratories.