[DNA diagnosis of inherited metabolic diseases]

In recent years, dramatic advances in the applications of molecular genetic techniques have made it possible to identify molecular defects in man that account for inherited metabolic diseases. Thus molecular genetic techniques has rapidly expanded our ability to diagnose disease. DNA diagnosis includes prenatal and presymptomatic diagnosis as well as identification of carriers of many inherited metabolic disorders. Disorders that are always caused by a specific mutation can be diagnosed by direct detection of the mutation, while diagnosis of disorders with genetic heterogeneity or unknown genetic defect can be based on polymorphism in linkage analysis. DNA amplification by the PCR has made possible the rapid identification of DNA sequences variations. After PCR, mutations can be detected by various methods such as restriction enzyme analysis, amplification refractory mutation system, dot blot hybridization, chemical cleavage, or single strand conformational polymorphism. In addition, the PCR technique can be applied to polymorphism analysis. These methods have made DNA diagnosis quicker, easier, and cheaper.