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XYY Syndrome

(47,XYY Syndrome)

By

Nina N. Powell-Hamilton

, MD, Sidney Kimmel Medical College at Thomas Jefferson University

Reviewed/Revised Nov 2023
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The sex chromosomes Sex chromosomes Genes are segments of deoxyribonucleic acid (DNA) that contain the code for a specific protein that functions in one or more types of cells in the body or the code for functional ribonucleic... read more Sex chromosomes determine whether a fetus becomes male or female. A pair of X and Y chromosomes (XY) results in a male, and a pair of X and X chromosomes (XX) results in a female.

About 1 in every 1,000 boys is born with XYY syndrome.

XYY syndrome was once thought to cause aggressive or violent criminal behavior, but this theory has been disproved.

NOTE: This is the Consumer Version. DOCTORS: VIEW PROFESSIONAL VERSION
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