Seventeen alpha-hydroxylase deficiency with one base pair deletion of the cytochrome P450c17 (CYP17) gene.

Mutation of the cytochrome P450c17 (CYP17) gene causes 17 alpha-hydroxylase deficiency (17OHD). Recently, several researchers have elucidated the molecular basis of 17OHD by gene analysis. We experienced a case of 17OHD and intended to reveal the abnormality of the CYP17 gene in this Japanese female with 17OHD. Leukocytes were obtained from the patient, her mother and sister, and normal control subjects. We amplified the CYP17 gene using polymerase chain reaction and performed the sequence analysis using the dideoxy terminator method and restriction enzyme analysis. We found that the patient had one base-pair deletion at the position of amino acid 438. An identical result was obtained with restriction enzyme analysis. This G deletion altered the reading frame and resulted in a premature stop codon at position 443; the ligand of heme iron (Cys: cystine 442) was absent. This small mutation may account for the patient's clinical manifestations of 17OHD. This is the first case of 17OHD with only one base pair deletion of the CYP17 gene.