In 1942, Dr. Harry Klinefelter and his coworkers at the Massachusetts General Hospital in Boston published a report about nine men who had enlarged breasts, sparse facial and body hair, small testes, and an inability to produce sperm. Reserachers later discovered that men with this condition, which was later termed Klinefelter's syndrome, had an extra sex chromosome, XXY instead of the usual male arrangement, XY.
XXY boys do not progress normally through puberty. Their testes remain child-sized and therefore do not produce enough of the male hormone testosterone. As adolescents, XXY boys are taller than average and may lack facial hair. About one-third of XXY boys will develop enlarged breasts, a condition known as gynecomastia. This is different than just fat accumulation that gives the appearance of having breasts-it is true breast development. These males with enlarged breasts have the same risk of breast cancer as women do. In other words, XXY males are 20 to 50 times more likely than the average male to develop breast cancer. Unlike women, though, XXY males are more likely to develop cancer in both breasts or unusual second types of cancer.
|
