47,XYY syndrome

XYY Karyotype; XYY syndrome; YY syndrome

XYY syndrome is an aneuploidy (specifically a trisomy) of the sex chromosomes in which a human male receives an extra Y chromosome, producing a 47,XYY karyotype. Some medical geneticists (Allanson & Graham 2002) question whether the term "syndrome" is appropriate for this condition because its phenotype is normal and the vast majority (an estimated 97% in the UK) of 47,XYY males do not know their karyotype. Effects Physical traits Most often, this chromosomal change causes no unus ...