Klinefelter syndrome
| Klinefelter syndrome | |
|---|---|
| Other names | XXY syndrome, Klinefelter's syndrome, Klinefelter-Reifenstein-Albright syndrome |
| 47,XXY karyotype | |
| Pronunciation |
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| Specialty | Medical genetics |
| Symptoms | Varied; include above average height, weaker muscles, poor coordination, less body hair, breast growth, small testicle size, sexual dysfunction, infertility |
| Complications | Infertility, intellectual disability, autoimmune disorders, breast cancer, venous thromboembolic disease, osteoporosis |
| Usual onset | At fertilisation |
| Duration | Lifelong |
| Causes | Nondisjunction during gametogenesis or in a zygote |
| Risk factors | Older age of mother |
| Diagnostic method | Genetic testing (karyotype) |
| Prevention | None |
| Treatment | Physical therapy, speech and language therapy, Testosterone Supplementation, counseling |
| Prognosis | Nearly normal life expectancy |
| Frequency | 1 in 500–1000 |
| Named after | Harry Klinefelter |
Klinefelter syndrome (KS), also known as 47,XXY, is a chromosome anomaly where a male has an extra X chromosome. These complications commonly include infertility and small, poorly functioning testicles (if present). These symptoms are often noticed only at puberty, although this is one of the most common chromosomal disorders. The birth prevalence of KS in the State of Victoria, Australia was estimated to be 223 per 100,000 males. It is named after American endocrinologist Harry Klinefelter, who identified the condition in the 1940s, along with his colleagues at Massachusetts General Hospital.
The syndrome is defined by the presence of at least one extra X chromosome in addition to a Y chromosome, yielding a total of 47 or more chromosomes rather than the usual 46. Klinefelter syndrome occurs randomly. The extra X chromosome comes from the father and mother nearly equally. An older mother may have a slightly increased risk of a child with KS. The syndrome is diagnosed by the genetic test known as karyotyping.