Alternate Names : XXY Syndrome
How is the condition diagnosed?
Klinefelter syndrome usually is not obvious at birth, unless some of uncommon physical features are present. It may be suspected at puberty, when secondary sexual characteristics do not develop. The penis usually enlarges normally, but the testicles remain small and beard growth is sparse. In addition, breasts may enlarge at puberty. While measuring certain hormones is useful, chromosome analysis is the definitive diagnostic test.