Porphobilmogen deaminase gene mutations in Brazilian acute intermittent porphyria patients

Acute intermittent porphyria (AIP) is an autosomal dominant disorder resulting from porphobilmogen deaminase (PBGD) deficiency. Seven unrelated Brazilian patients were investigated regarding PBGD gene mutations by polymerase chain reaction (PCR) and single strand conformation polymorphism (SSCP) analysis followed by direct DNA sequencing. The PBG gene screening disclosed abnormal SSCP patterns in exons 7, 9, 12, 13, and 15, as well as in introns 3 and 10. Direct DNA sequencing revealed the occurrence of three nonsense mutations (R149X, R225X, and R325X) in exons 9, 12, and 15, respectively, and one missense mutation G111R in exon 7. The G111R mutation was detected in two unrelated patients. Intragenic polymorphisms (3119G/T in intron 2, 3581G/A in intron 3, 7052A/G and 7064C/A in intron 10, and -65C/T in exon 1) were also observed. In addition, two silent mutations (V202V in exon 10 and A266A in exon 13) were found. The latter has not heretofore been reported. Thus, this study revealed the mutations involved in Brazilian symptomatic AIP patients, as well as the intragenic polymorphisms found in the patients.