ACUTE INTERMITTENT PORPHYRIA - LABORATORY DIAGNOSIS BY MOLECULAR METHODS

Acute intermittent porphyria is a neurologic disorder caused by a part ial deficiency of porphobilinogen (PBG) deaminase, the third enzyme in the synthetic pathway for heme. The isolation and characterization of the gene for PBG deaminase has brought molecular techniques for diagn osing the disease within reach. Over 60 mutations causing acute interm ittent porphyria have been found, most of which are confined to one or several families. Because no single mutation accounts for more than a fraction of cases, screening techniques for locating and identifying unknown mutations are very important. Once a mutation has been charact erized, testing of family members is straightforward, and gene carrier s can be identified or excluded with greater accuracy than is possible with conventional biochemical tests.