Most people have 46 chromosomes in each cell. In males, this typically includes one X chromosome and one Y chromosome (XY). XYY syndrome is a genetic condition that occurs when a male has an extra ...

The first five above are the most common physical exam findings. However, because these characteristics can fall within the normal range for males, often those with XYY syndrome do not get diagnosed.

Superman syndrome, also known as 47, XYY, is a condition classified as a chromosomal aneuploidy (which is an abnormality in chromosome structure and/or number) in which males have an additional Y ...