Klinefelter syndrome (KS) is a chromosomal anomaly, which in most cases is characterised by 47 chromosomes instead of the usual 46.
The estimated incidence is 0.15-0.2% of live births.
- the testes are normal prior to puberty and small in post pubertal testes; there is absent spermatogenesis
- the kidneys can be symmetrically enlarged with small 1-8 mm cysts
- post pubertal gynaecomastia
- sparse facial and axillary hair
- tall stature
- narrow shoulders
- broad hips
- normal to moderately reduced Leydig cell function
- increased secretion of follicle-stimulating hormone
- androgen deficiency
- normal to slightly decreased verbal intelligence
- ~80% have 47XXY
- ~10% have mosaic 46XY/47XXY
- ~10% have 48XXYY and other less frequent types
These abnormal divisions occur as sporadic events and are not hereditary.
Treatment and prognosis
- increased incidence of male breast malignancy
- increased incidence of germ cell tumors, particularly in the mediastinum 6.
History and etymology
It is named after Harry Klinefelter who first described the syndrome in 1942.
- 1. Gruchy N, Vialard F, Decamp M et-al. Pregnancy outcomes in 188 French cases of prenatally diagnosed Klinefelter syndrome. Hum. Reprod. 2011;26 (9): 2570-5. doi:10.1093/humrep/der193 - Pubmed citation
- 2. Herlihy AS, Halliday JL, Cock ML et-al. The prevalence and diagnosis rates of Klinefelter syndrome: an Australian comparison. Med. J. Aust. 2011;194 (1): 24-8. Med. J. Aust. (link) - Pubmed citation
- 3. Frühmesser A, Kotzot D. Chromosomal variants in klinefelter syndrome. Sex Dev. 2011;5 (3): 109-23. doi:10.1159/000327324 - Pubmed citation
- 4. Bojesen A, Gravholt CH. Morbidity and mortality in Klinefelter syndrome (47,XXY). Acta Paediatr. 2011;100 (6): 807-13. doi:10.1111/j.1651-2227.2011.02274.x - Pubmed citation
- 5. Wikström AM, Dunkel L. Klinefelter syndrome. Best Pract. Res. Clin. Endocrinol. Metab. 2011;25 (2): 239-50. doi:10.1016/j.beem.2010.09.006 - Pubmed citation
- 6. Curry WA, McKay CE, Richardson RL, Greco FA. Klinefelter's syndrome and mediastinal germ cell neoplasms. J Urol. 1981 Jan;125(1):127-9. Pubmed citation