Human Genetics Handout Spr08

Severe mental retardation facial anomalies abnormal

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Unformatted text preview: istress, hence the name Cri du Chat. Severe mental retardation, facial anomalies, abnormal development of the glottis and larynx. Frequency = 1/100,000 live births. X AND Y CHROMOSOME ABNORMALITIES ***Turner Syndrome (XO): Female, short, broad chest and neck, infertile, rudimentary ovaries, and underdeveloped secondary sexual characteristics. There is no mental retardation associated with this syndrome and it is not associated with any life threatening problems. Frequency is 1/10,000 female births. ***Klinefelter Syndrome (XXY): Male, infertile, with somewhat feminine secondary sexual characteristics, some degree of subnormal intelligence. Frequency is 1/1000 male births. Other forms of Klinefelter have been found including XXXY and XXXXY. The additional X chromosomes increase the severity of phenotypic symptoms and brings out clear-cut mental retardation. ***XXX Syndrome: Most of these females are clinically normal, although there is a slightly increased chance for sterility and mental retardation compared to normal females. Frequency = 1/1000 female births. ***XYY Syndrome: Males above average in height and below average intelligence. Possibly more aggressive than the "normal" male, but that is more likely a socialized behavior related to size and slightly subnormal intelligence. Frequency = 1/1,000 male births....
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