User:Mr. Ibrahem/XYYY syndrome

XYYY syndrome, also known as 48,XYYY, is a chromosomal disorder in which a male has two extra Y chromosomes. Symptoms may include mild intellectual disability, irregular teeth, infertility, radioulnar synostosis, and tall stature.

The underlying mechanism is believed to involve fertilization of a normal egg by a sperm containing three Y chromosomes. Such a sperm could be produced by nondisjunction during meiosis. In some, only part of their cells are affected. Diagnosis is by genetic testing, often a karyotype, though other techniques may be used. It is a type of sex chromosome aneuploidy.

Speech therapy and educational support may be required. Outcomes are generally okay, with a reasonable life expectancy. XYYY syndrome is exceptionally rare, with about 10 reported cases as of 2018. Though, further undiagnosed cases may exist. The condition was first described in 1965.