ACUTE INTERMITTENT PORPHYRIA CAUSED BY A SINGLE-BASE INSERTION OF C IN EXON-15 OF THE PORPHOBILINOGEN DEAMINASE GENE THAT RESULTS IN A FRAME-SHIFT AND PREMATURE STOPPING OF TRANSLATION

A single base insertion of C in exon 15 of the porphobilinogen deamina se (PBG-D) gene was observed in a patient with acute intermittent porp hyria (AIP) by polymerase chain reaction (PCR)-direct sequencing analy sis. The insertion locates between positions -22 and -21 from the tran slation termination codon TAA, causes a frame shift, and results in a stop codon located 4 codons downstream from the insertion (premature s topping of translation). The mutation generates an MspI recognition si te, which can be used, in turn, to detect the mutant allele. Analysis of the cDNA fragments amplified by PCR revealed the existence of the a bnormal PBG-D mRNA from the mutant allele in the patient.