Klinefelter syndrome is a chromosome disorder in males that results in hypogonadism (small penis and small firm testicles).
Hypogonadism is the condition in which the production of sex hormones and germ cells (sperm and eggs) is inadequate.
Hypogonadism may occur at any age; however, consequences differ according to the age at onset.
If hypogonadism occurs prenatally (even if incomplete), sexual ambiguity may result.
If hypogonadism occurs before puberty, puberty does not progress.