Klinefelter's syndrome, 47, XXY or XXY syndrome is a condition caused by a chromosome aneuploidy. Affected males have an extra X sex chromosome. The principal effect is small testes development and reduced fertility. A variety of other physical and behavioral differences and problems are common, though severity varies and many boys and men with the condition have few detectable symptoms. It is the second most common extra chromosome condition, and is named after Dr. Harry Klinefelter, an endocrinologist at Massachusetts General Hospital, Boston, Massachusetts, who first described it in 1942. The condition exists in roughly 1 out of every 500 to 1,000 males.
"What's wrong with that guy? Is he gay?"
"No, he has Klinefelter's syndrome"
"So is he a dude or a chick?"
-_- "Anyone with a Y chromosome is biologically considered male."
Klinefelter's syndrome is a genetic disorder which means that men have an XXY chromosome set up rather than the usual XY (for a male). The XXY almost always causes feminisation of men or anti-masculinisation. Klinefelter's syndrome can be extreme or non-apparent depending on the person. Usual symptoms can be :
Voice not breaking
Long arms or legs
testicular atrophy (small testicles)
Crossdresser's would probably like to have klinefelter's syndrome so that they would look girlier.