OBJECTIVETo detect CYP17A1 gene mutation in a patient with 17 alpha-hydroxylase/17, 20-lyase deficiency and her family members.

METHODGenomic DNA was extracted from the blood of the patient, her parents and twin sister. The 8 exons of CYP17A1 gene were amplified with polymerase chain reaction (PCR) and screened for mutations by sequencing.

RESULTThe analysis revealed that the patient was a compound heterozygote carrying two different inherited point mutations on CYP17A1 gene. They were nt186delC on exon 1 and nt1085G > A on exon 6. This type of mutation could induce 17OHD because of complete loss of 17 alpha-hydroxylase activities. And her parents and the twin sister were carriers on CYP17A1 gene. In addition, the mutation nt186delC was a novel point mutation and it was not discovered in normal children.

CONCLUSIONA new compound heterozygote carrying two different inherited point mutations on CYP17A1 gene was found, and her parents and twin sister were carriers. This is probably the first report in the world of a twin sisters of whom one is a patient with 17OHD and the other is a carrier of CYP17A1 gene mutation.