Aromatase excess syndrome

Aromatase excess syndrome
Other names	Hereditary prepubertal gynecomastia
AEXS results when the function of aromatase is hyperactive. The aromatase protein (pictured) is responsible for the biosynthesis of estrogens like estradiol in the human body.
Specialty	Endocrinology

Aromatase excess syndrome (AES or AEXS) is a rarely diagnosed genetic and endocrine syndrome which is characterized by an overexpression of aromatase, the enzyme responsible for the biosynthesis of the estrogen sex hormones from the androgens, in turn resulting in excessive levels of circulating estrogens and, accordingly, symptoms of hyperestrogenism. It affects both sexes, manifesting itself in males as marked or complete phenotypical feminization (with the exception of the genitalia; i.e., no ambiguous genitalia) and in females as hyperfeminization.^[1][2][3][4]

To date, 30 males and 8 females with AEXS among 15 and 7 families, respectively, have been described in the medical literature.^[1][2]