pediatrics
47,XYY Syndrome
Introduction
47,XYY syndrome is the presence of two Y chromosomes and one X chromosome in a phenotypic male. (See also Overview of Chromosomal Abnormalities and see The 47,XYY syndrome occurs in approximately 1/1000 live male births. Affected boys tend to be taller than average and have a 10- to 15-point IQ reduction compared with family members. There are few physical problems. Minor Overview of Behavioral Problems in Children , hyperactivity, XYY syndrome was once thought to cause aggressive or violent criminal behavior, but this theory has been disproved. 