Mutation Analysis of 17α-Hydroxylase

17α-hydroxylase is a rare form of congenital adrenal hyperplasia. Patients with complete 17α-hydroxylase deficiency may come to attention to the doctor at their early adulthood due to hypertension or disordered puberty. 17α-hydroxylase is a form of cytochrome P450 enzyme in the adrenal cortex for the production of cortisol, while 17,20-lyase is required in both adrenal glands and the gonads for the production of androgen precursors of sex hormones. Therefore, patients with 17α-hydroxylase will presented with elevated deoxycorticosterone (DOC) level and decreased aldosterone and cortisol level. Because DOC is the second most important naturally occurring mineralocorticoid hormone, hypertension and hypokalemic alkalosis will be noted in these patients. Besides, deficiency of 17,20-lyase activity will lead to impairment of virilization in 46 XY patients and deficient estrogen production in 46 XX patients.

The P450c17 has both 17α-hydroxylase and 17,20-lyase activity and are encoded by the CYP17 gene. The sequence of CYP17 gene was established in 1987 and more than 40 mutations were identified till now. The purpose of this study is to elucidate the molecular pathology of the 4 families with 17α-hydroxylase/17,20-lyase deficiency.