A late 17α-hydroxylase deficiency diagnosis that leads to the discovery of a new CYP17 gene mutation.

17α-Hydroxylase deficiency is a rare form of congenital adrenal hyperplasia. It leads to a reduced production of cortisol and sex steroids and thus an increase in adrenocorticotrophic hormone and gonadotrophins levels. High adrenocorticotrophic hormone levels result in an accumulation of 17-deoxysteroids, such as deoxycorticosterone and corticosterone. Deoxycorticosterone and corticosterone have an important mineralocorticoid activity. We report the case of a 66-year-old woman who presented with hypertension and symptomatic hypokalaemia. Primary hyperaldosteronism was suspected and a right adrenal mass was removed. After surgery, the patient was referred to the endocrinology department for persistant hypokalaemia. Actually, she presented some signs of hypogonadism (impuberism, primary amenorrhea, infertility). Cortisol and 17OH-progesterone serum levels were low. Deoxycorticosterone and corticosterone were markedly elevated. The hypothesis of 17α-hydroxylase deficiency was considered and confirmed by genetic exploration. A non-sense mutation c.938G>A (p.Trp313X) in exon 5 of the CYP17 gene was found that had never been reported so far to our knowledge. Moreover, the patient's karyotype found a mosaic Turner syndrome. This case is particularly interesting because of the delay of diagnosis. The 17α-hydroxylase deficiency diagnosis is to be considered when hypertension is associated with hypokalaemia and hypogonadism, even in adult patients.