A 16-year-old girl presents with primary amenorrhoea. She has well-developed breasts (Tanner stage 4), scanty pubic hair, and bilateral inguinal swellings. Ultrasound shows absence of uterus. Testosterone is in the adult male range and karyotype is 46,XY. What is the underlying defect?

• A 17-ketosteroid reductase deficiency
• B 5-alpha reductase deficiency
• C Gonadal dysgenesis with streak gonads
• D Defective androgen receptor function ✓

Explanation

Complete androgen insensitivity syndrome results from mutation of the androgen receptor gene on the X chromosome. Testosterone levels are normal or high, but target tissues cannot respond, so Wolffian structures regress and external genitalia are female. AMH from functioning testes removes the uterus. Breasts develop because peripheral aromatization of testosterone produces estrogen. The absent pubic and axillary hair, despite high testosterone, points directly to receptor failure rather than hormone deficiency.

Reference: Williams Textbook of Endocrinology, 14th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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