A 16-year-old girl presents with primary amenorrhoea. She is short (height 145 cm), has a webbed neck, widely spaced nipples, Tanner stage III breast development, and sparse pubic hair. Ultrasound shows a small uterus with bilateral streak gonads. Which karyotype is most likely?
- A 46,XX
- B 46,XY
- C 45,X ✓
- D 47,XXY
Correct answer: C. 45,X
Explanation
Turner syndrome (45,X) presents with primary amenorrhoea due to streak gonads, hypergonadotropic hypogonadism with high FSH, short stature, webbed neck, shield chest with widely spaced nipples, and coarctation of the aorta. The presence of breast development at Tanner III suggests mosaicism rather than pure 45,X, but the classic phenotype points to a monosomy X line. 46,XY would give absent uterus as in androgen insensitivity or Swyer syndrome, both of which have normal height.
Reference: Williams Gynecology, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.