Which presentation may occur in affected newborn boys with classic CAH, depending on genotype?

• A. Salt-wasting crisis.
• B. Ambiguous genitalia at birth.
• C. Hypertension with edema.
• D. Salt-wasting crisis or virilization at puberty, depending on genotype.

Answer: (D)

In classic CAH from 21-hydroxylase deficiency, how the disease shows up depends on how much enzyme activity the genotype still allows. Severe mutations wipe out the enzyme, leading to cortisol and aldosterone deficiency right in infancy, which causes a salt-wasting crisis. Milder mutations leave some enzyme activity, so salt-wasting may not occur, but androgens rise and a virilization pattern can emerge later, sometimes becoming evident at puberty. For newborn boys, this means you can see either a salt-wasting crisis early on or later signs of androgen excess (virilization) as they go through puberty, depending on the specific genotype. Hypertension with edema points to other forms like 11β-hydroxylase deficiency, and ambiguous genitalia at birth is more characteristic of affected females.