<unk> , also known as 49,XYYYY, is an exceptionally rare chromosomal disorder in which a male has three additional copies of the Y chromosome. Only seven non-mosaic cases of the disorder have ever been recorded in the medical literature, as well as five mosaic cases, of which two had more 48,XYYY than 49,XYYYY cells. Due to the extreme rarity of the disorder, little is understood about it, and the phenotype appears to be variable.
XYYYY syndrome
XYYY syndrome
XYY syndrome
XXYY syndrome
Joubert syndrome
XX male syndrome
Klinefelter syndrome
Ring chromosome 20 syndrome