Question:hard
Least common cause of ambiguous genitalia in a female child?
Least common cause of ambiguous genitalia in a female child?
Show Hint
Which listed enzyme defect causes ichthyosis and low maternal estriol rather than virilisation?
Updated On: Jun 24, 2026
- Placental steroid sulfatase deficiency
- Fetal aromatase deficiency
- WT-4 mutation
- Congenital adrenal hyperplasia (CAH)
Show Solution
The Correct Option is A
Solution and Explanation
When a chromosomally female baby shows ambiguous genitalia, the underlying theme is usually too much androgen acting on the developing external genitalia. Ranking the options by how often they explain this picture clarifies the answer. Congenital adrenal hyperplasia sits at the top, since enzyme blocks such as 21-hydroxylase deficiency redirect steroid synthesis toward androgens and virilise the female infant, so it is the leading cause. Aromatase deficiency is the next logical culprit because, without the enzyme that turns androgens into oestrogens, androgen levels climb in the fetus and masculinise the genitalia. Disturbances in the WT pathway interfere with gonadal differentiation and can therefore generate disorders of sex development as well. That leaves placental steroid sulfatase deficiency, whose principal consequences are reduced maternal oestriol and X-linked ichthyosis in the child rather than virilisation of the female external genitalia. Because it rarely produces ambiguous genitalia, it is the least common cause among the choices.
\[\boxed{\text{Placental steroid sulfatase deficiency}}\]
\[\boxed{\text{Placental steroid sulfatase deficiency}}\]
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