RÉSUMÉ
The single enzyme P-450c17 hydroxylase catalyzes the 17a-hydroxylation of both pregnenolone and progesterone and the side-chain cleavage of 17a-hydroxypregnenolone and 17a-hydroxypro- gesterone to dehydroepiandrosterone and androstenedione. This enzyme is located in the endoplasmic reticulum and consists of a P-450c17 and a specific flavoprotein NADPH-cytochrome P-450 reductase. The clinical picture and hormonal pattern in 17a-hydroxylase deficiency have been consistent in both genotypic sexes with hypergonadotropic hypogonadism in whom the virtual absence of gonadal steroids results in a female phenotype with primary amenorrhea and pseudohermaphro- ditism in the male and underdeveloped secondary sex characteristics and hypermineralocorticoidism with hypertension, hypokalemia, suppressed renin-angiotensin system and extremely reduced aldo-sterone production. A 17-year-old girl visited endocrine clinic because of amenorrhea, absence of pubic and axillary hair, and hypertension. she had elevated levels of serum corticosterone, deoxycorticosterone(DOC), 18-hydroxycorticosterone(18-OHB). Stumulation with ACTH effected minimal increase in the elevated steroids and the ACTH-stimulated 18-OHB to aldosterone ratio was more than 280. These hormonal patterns appear to be homozygote in 17a-hydroxylase deficiency.