A rare chromosomal anomaly among males, resulting in both mental and physical defects. These individuals have three sex chromosomes, generally two X and one Y, instead of the normal one X and one Y for males and two X for females. They are usually tall and lean, with enlarged breasts, atrophied testes, and no sperm production. These characteristics are usually accompanied by severe mental retardation. See MENTAL RETARDATION (CAUSES).

Cite this page: N., Pam M.S., "KLINEFELTER’S SYNDROME," in PsychologyDictionary.org, November 28, 2018, https://psychologydictionary.org/klinefelters-syndrome-2/ (accessed March 16, 2019).