Question

A female presents with an XO genotype and primary amenorrhoea. What is the most likely diagnosis?

• A. Gonadal dysgenesis
• B. Androgen insensitivity syndrome
• C. Mayer-Rokitansky-Kuster-Hauser (MRKH) syndrome
• D. Congenital adrenal hyperplasia (CAH)

Hint:

XO equals Turner syndrome; the ovaries become non-functional streak gonads.

Answer 1

The Correct Option is A

Step 1: Identify the karyotype. A 45,XO genotype is the classic karyotype of Turner syndrome.
Step 2: Link karyotype to gonadal status. In Turner syndrome the single X is insufficient for ovarian maintenance, so the ovaries are replaced by fibrous tissue (streak gonads). This is termed gonadal dysgenesis.
Step 3: Explain the amenorrhoea. Streak (dysgenetic) gonads produce little or no oestrogen, so secondary sexual characters fail to develop and menstruation never starts, giving primary amenorrhoea with raised FSH and LH (hypergonadotropic hypogonadism).
Step 4: Exclude the other options. Androgen insensitivity syndrome has a 46,XY karyotype with testes; MRKH has a normal 46,XX karyotype with absent uterus and vagina but normal ovaries; CAH is associated with a 46,XX karyotype and ambiguous genitalia, not XO.
Conclusion: XO with primary amenorrhoea is gonadal dysgenesis of Turner syndrome. The printed key (A) is medically correct.