As its name indicates, a person with the syndrome has one Y chromosome and four X chromosomes on the 23rd pair, thus having forty-nine chromosomes rather than the normal forty-six. As with most categories of aneuploidy disorders, 49,XXXXY syndrome is often accompanied by intellectual disability. It can be considered a form or variant of Klinefelter syndrome (47,XXY). Individuals with this syndrome are typically mosaic, being 49,XXXXY/48,<unk>  It is genetic but not hereditary, meaning that while the genes of the parents cause the syndrome, there is a small chance of more than one child having the syndrome. The probability of inheriting the disease is about one percent.
XXXXY syndrome
XXYY syndrome
XX male syndrome
XYY syndrome
XYYY syndrome
Ring chromosome 20 syndrome
Apert syndrome
XYYYY syndrome