It's quite common - about 1 in 500 boy babies have Klinefelter's and it is more likely to occur the older the mother. Typical physical features People who have Klinefelter's syndrome tend to have a distinctive physical appearance although in childhood it may go unnoticed and it is often not until puberty that these features develop. A normal life for most Most men with Klinefelter's syndrome lead a very normal life, with the same sort of family, home, school and work joys and stresses that we all face. Many are infertile, because the testes don't develop and fail to produce sperm. Learning disabilities are more common among men with Klinefelter's, although many are very academically capable.
Some medical conditions are more common, especially diabetes, thyroid problems and asthma.
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