(See also Overview of Chromosomal Abnormalities Overview of Chromosomal Abnormalities Chromosomal abnormalities cause various disorders. Abnormalities that affect autosomes (the 22 paired chromosomes that are alike in males and females) are more common than those that affect... read more and see Overview of Sex Chromosome Abnormalities Overview of Sex Chromosome Abnormalities Sex chromosome abnormalities may involve aneuploidy, partial deletions or duplications of sex chromosomes, or mosaicism. (See also Overview of Chromosomal Abnormalities.) Sex chromosome abnormalities... read more .)
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 behavior disorders Overview of Behavioral Problems in Children Many behaviors exhibited by children or adolescents concern parents or other adults. Behaviors or behavioral patterns become clinically significant if they are frequent or persistent and maladaptive... read more , hyperactivity, attention-deficit disorder Attention-Deficit/Hyperactivity Disorder (ADD, ADHD) Attention-deficit/hyperactivity disorder (ADHD) is a syndrome of inattention, hyperactivity, and impulsivity. The 3 types of ADHD are predominantly inattentive, predominantly hyperactive/impulsive... read more , and learning disorders Overview of Learning Disorders Learning disorders are conditions that cause a discrepancy between potential and actual levels of academic performance as predicted by the person’s intellectual abilities. Learning disorders... read more are more common.
XYY syndrome was once thought to cause aggressive or violent criminal behavior, but this theory has been disproved.