Unformatted text preview: Additional X chromosomes are associated with an increased mental handicap. XXY - Klinefelter Syndrome (also XXXY) Males with two or more X chromosomes have Klinefelter Syndrome. The incidence of Klinefelter Syndrome is 1 in 1000 male births. Symptoms include reduced sexual maturity and secondary sexual characteristics, breast swelling (gynecomastia), and infertility. Klinefelter males are slow to learn and individuals with additional X’s (XXXY) may be mentally retarded. XYY - Jacob Syndrome Most XYY males are normal and are unaware of an additional chromosome. XYY males tend to be tall and may have speech and reading problems....
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- Fall '10
- Biology, X chromosome, Y chromosome, Turner syndrome, XYY Syndrome