A girl has had no breast development by the age of 13 years. Which condition should be suspected?

Answer: A. Turner syndrome

Delayed pubertal development

The first sign of breast development normally appears around age 9 and is completed by about 13. If there is no breast development by age 13, suspect Turner's syndrome.

Turner syndrome (45,X)

• Gonadal dysgenesis (streak ovaries) leads to oestrogen deficiency, causing absent/delayed breast development and primary amenorrhoea.
• Other features: short stature, webbed neck, widely spaced nipples, cardiac (coarctation) and renal anomalies.

Why A

Absent breast development by 13 is a classic prompt to suspect Turner syndrome (and to investigate delayed puberty, e.g. karyotype, FSH/LH).

Why the others are wrong

Precocious puberty is early (not absent) development; AIS has normal breast development; CAH causes virilisation; absent development by 13 warrants investigation, not simple reassurance.