Hereditary aromatase deficiency is a rare disorder resulting in estrogen deficiency and androgen excess. An affected female may show a number of clinical findings.


Inheritance: autosomal recessive


Affected gene: CYP19A1

Affected enzyme: aromatase cytochrome P450 (P450arom)

Consequence of mutation: defect in the final step in the conversion of C19 steroids to estrogens, resulting in low estrogen and high androgen levels


Clinical features:

(1) virilization at birth (female pseudohermaphroditism)

(2) delayed epiphyseal closure/fusion with delayed bone age

(3) tall stature, starting with puberty

(4) osteopenia and osteoporosis with recurrent bone fractures

(5) pubertal failure

(6) virilization (acne, cliteromegaly, hirsutism, deepening of the voice, male pattern hair loss)

(7) hypergonadotrophic hypogonadism with cystic ovaries

(8) variable acanthosis nigricans


Laboratory findings:

(1) no excess in growth hormone

(2) high normal or elevated serum testosterone

(3) high normal or elevated gonadotropins (FSH, LH)

(4) low serum estrogens

(5) variable hyperinsulinemia


Differential diagnosis:

(1) polycystic ovary syndrome (PCOS)


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