A 13-year-old girl is brought to the clinic by her mother for a yearly physical examination. The patient feels well but is worried that she has not yet started puberty. Temperature is 36.7 C (98 F), blood pressure is 152/91 mm Hg, pulse is 75/min, and respirations are 18/min. Physical examination is significant for a lack of secondary sexual characteristics; a blind vagina is noted on pelvic examination. Laboratory studies reveal hypokalemia and low testosterone and estradiol levels. Cytogenetic analysis shows a 46,XY karyotype. This patient most likely has deficiency of which of the following enzymes?

Question

A 13-year-old girl is brought to the clinic by her mother for a yearly physical examination.  The patient feels well but is worried that she has not yet started puberty.  Temperature is 36.7 C (98 F), blood pressure is 152/91 mm Hg, pulse is 75/min, and respirations are 18/min.  Physical examination is significant for a lack of secondary sexual characteristics; a blind vagina is noted on pelvic examination.  Laboratory studies reveal hypokalemia and low testosterone and estradiol levels.  Cytogenetic analysis shows a 46,XY karyotype.  This patient most likely has deficiency of which of the following enzymes?

Quizplus · Accepted Answer

Eductional Objective: Deficiency of 17 alpha-hydroxylase is a rare form of congenital adrenal hyperplasia characterized by impaired synthesis of androgens, estrogens, and cortisol with excess production of mineralocorticoids.  Genetic males with this deficiency may have phenotypically female external genitalia and present with hypertension and hypokalemia around the expected time of puberty.

A 13-Year-Old Girl Is Brought to the Clinic by Her