NCIt related terms : Klinefelter's Syndrome, XXY; 47,XXY Syndrome;
NCIt definition : A sex chromosome disorder caused by the presence of an extra X chromosome in the male
karyotype. Affected individuals are infertile and have a small penis and testes. They
tend to have tall stature and long legs and may have difficulties with speech and
language development. Gynecomastia may be present.;
Alternative definition : NCI-GLOSS: A genetic disorder in males caused by having one or more extra X chromosomes.
Males with this disorder may have larger than normal breasts, a lack of facial and
body hair, a rounded body type, and small testicles. They may learn to speak much
later than other children and may have difficulty learning to read and write. Klinefelter
syndrome increases the risk of developing extragonadal germ cell tumors and breast
cancer.; NICHD: A condition caused by the presence of an extra X chromosome resulting in 47,XXY
karyotype in an individual with male phenotype. The condition is characterized in
childhood by relative tall stature with disproportionately long limbs, and speech/language
developmental problems in some patients. Postpubertal findings include small testes,
gynecomastia, and infertility.;