It is a chromosomal condition that affects male sexual development. Males with this condition typically have small testes that do not produce enough testosterone, which is the hormone that directs male sexual development before birth and during puberty.
Most males with this syndrome have one extra copy of the X chromosome in each cell.
In addition to affecting male sexual development, variants of Klinefelter syndrome are associated with intellectual disability, distinctive facial features, skeletal abnormalities, poor coordination, and severe problems with speech.
It is a genetic disorder that affects a girl’s development. The cause is a missing or incomplete X chromosome. Girls who have it are short, and their ovaries don’t work properly. Most are infertile. They are at risk for health difficulties such as high blood pressure, kidney problems, diabetes, cataracts, osteoporosis, and thyroid problems.