OTHER TOPICS IN THIS CHAPTER
- Overview of Chromosomal Abnormalities
- Down Syndrome (Trisomy 21)
- Trisomy 18
- Trisomy 13
- Chromosomal Deletion Syndromes
- Microdeletion and Microduplication Syndromes
- Overview of Sex Chromosome Abnormalities
- Turner Syndrome
- Klinefelter Syndrome (47,XXY)
- 47,XYY Syndrome
- Other X Chromosome Abnormalities
- Fragile X Syndrome
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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 Overview of Sex Chromosome Abnormalities.)
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, hyperactivity, attention-deficit disorder, and learning disorders are more common.
XYY syndrome was once thought to cause aggressive or violent criminal behavior, but this theory has been disproved.
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