This quote was relayed to me by my buddy Vince – FP doc on the subtleties of differentiating between Androgen Insensitivity Syndrome and Klinefelter’s Syndrome:
“Well, yeah, it could be Klinefelter’s – but they usually present with a penis”
An explanation for non-medical types (because inside jokes are not cool): Androgen Insensitivity Syndrome (AIS) and Klinefelter’s Syndrome are genetic disorders that both result in males with feminine features. In Klinefelter’s (47, XXY), an extra X chromosome is the culprit, while in AIS, genetically male (46, XY) individuals fail to develop external genetalia and develop as phenotypic females (you’d never be able to tell – in fact, it’s usually only discovered when a patient presents with inguinal herniae or fails to begin menstruation).
Bonus fact: Klinefelter’s Syndrome is both the #1 sex chromosome disorder (1 in 500 to 1 in 1,000 live births) and the #1 genetic cause of hypogonadism & infertility in males. As subtle as AIS, it may go undiagnosed until a male presents with his wife for reproductive counseling.