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.

When news breaks, you need to understand what actually matters — and what to do about it. At Vox, our mission to help you make sense of the world has never been more vital. But we can’t do it on our ...

The birth prevalence of sex chromosome trisomies (SCT), that is individuals with an XYY, XXY or XXX sex chromosome constitution, is traditionally based on six surveys of unselected newborns carried ...