A NEW COMPOUND HETEROZYGOUS MUTATION (W17X, 436-]T) IN THE CYTOCHROMEP450C17 GENE CAUSES 17-ALPHA-HYDROXYLASE(5G)17,20-LYASE DEFICIENCY/

A genetic disorder in cytochrome P450c17 results in 17 alpha-hydroxyla se/17,20-lyase deficiency. In the present study, a Japanese patient wi th 17 alpha-hydroxylase/17,20-lyase deficiency underwent molecular ana lysis. The patient presented with complete female genitalia with a 46, XY karyotype, absent pubertal development, and hypertension. The exons and exon-intron boundaries of P450c17 genetic region were amplified a nd sequenced. DNA sequencing revealed a compound heterozygous mutation . One allele showed a G to A transition corresponding to a premature t ermination codon at tryptophane in codon 17 (W17X). The other allele s howed a G to T substitution at the fifth nucleotide from the splice do nor site in intron 2 (436+5G-->T). W17X was found in one allele of the father, and 436+5G-->T was found in one allele of the mother. A previ ous report presented a patient with 17 alpha-hydroxylase/17,20-lyase d eficiency who was homozygous for W17X. However, the present case is a novel 436+5G-->T mutation. Reverse transcription-PCR analysis using to tal ribonucleic acid isolated from the testes of the patient revealed that an intron 2 donor site mutation caused abnormal splicing, such th at exon 2 was spliced with intron 2. Skipping the exon alters the tran slational reading frame of exon 3 and introduces a premature terminati on codon. In semiquantitative analysis, the majority of the transcript for 436+5G-->T skips exon 2. The present findings indicate that in th is patient, 17 alpha-hydroxylase/17,20-lyase deficiency was caused by the compound heterozygous mutation of exon and splice site mutation in cytochrome P450c17 gene.