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aromatase excess syndrome
Aromatase excess syndrome (AES or AEXS), also sometimes referred to as familial hyperestrogenism or familial gynecomastia, is a rare 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 pseudohermaphroditism), in whom it fits the definition of a form of intersex, and in females as hyperfeminization.
To date, 10 families with AES have been fully described in the medical literature, of which 23 males and at least 6 females were characterized as displaying symptoms of the condition.〔
==Cause==
The root cause of AES is not entirely clear, but it has been elucidated that inheritable, autosomal dominant genetic mutations affecting ''CYP19A1'', the gene which encodes aromatase, are involved in its etiology.〔〔〔
Observed physiological abnormalities of the condition include a dramatic overexpression of aromatase and, accordingly, excessive levels of estrogens including estradiol and estrone, and a very high rate of peripheral conversion of androgens to estrogens. In one study, cellular aromatase mRNA expression was found to be at least 10 times higher in a female patient compared to the control, and the estradiol/testosterone ratio after an injection of testosterone in a male patient was found to be 100 times greater than the control.〔 Additionally, in another study, androstenedione, testosterone, and dihydrotestosterone (DHT) were found to be either low or normal in males, and follicle-stimulating hormone (FSH) levels were very low (likely due to suppression by estrogen, which has antigonadotropic effects as a form of negative feedback inhibition on sex steroid production in sufficiently high amounts), whereas luteinizing hormone (LH) levels were normal.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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