A 22-year-old woman has primary amenorrhea. On examination, she is phenotypically female, has normal breast development, scanty axillary and pubic hair, and a short vagina with no uterus on MRI. Karyotype is 46,XY. The MOST likely diagnosis is:

• A Turner syndrome (45,X)
• B Mayer-Rokitansky-Küster-Hauser syndrome
• C Complete androgen insensitivity syndrome (CAIS) ✓
• D 5-alpha reductase deficiency

Explanation

Complete androgen insensitivity syndrome (CAIS) presents with 46,XY karyotype, phenotypically female appearance with normal breast development (from testosterone aromatization to estrogen), absent/scanty body hair (androgen insensitivity), absent uterus (due to functioning Müllerian inhibiting factor from testes), and a blind-ending vagina. Gonads are intra-abdominal testes. MRKH syndrome has 46,XX karyotype with absent uterus but normal hair. 5-alpha reductase deficiency causes virilization at puberty. Turner syndrome has 45,X with stigmata of gonadal dysgenesis.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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