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Abnormal Meiosis : Nondisjunction

Abnormal Meiosis : Nondisjunction. Disorders Caused by Nondisjunction of Autosomal Chromosomes: There only 3 autosomal trisomies that result in a baby that can survive for a time after birth; the others are too devastating and the baby usually dies in utero.

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Abnormal Meiosis : Nondisjunction

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  1. Abnormal Meiosis: Nondisjunction

  2. Disorders Caused by Nondisjunction of Autosomal Chromosomes: There only 3 autosomal trisomies that result in a baby that can survive for a time after birth; the others are too devastating and the baby usually dies in utero. There are no instances of autosomal monosomies surviving after birth.

  3. Down Syndrome(trisomy 21):47, XX, +21 or 47, XY, +21 • The result of an extra copy of chromosome 21. • Down syndrome alters the child's physical appearance either moderately or severely. • characteristic facial features, short stature; heart defects, shorter lifespan

  4. often sexually underdeveloped and sterile, usually some degree of mental retardation. • Down Syndrome is correlated with age of mother but can also be the result of nondisjunction of the father's chromosome 21.

  5. B. Patau syndrome (trisomy 13):47, XY, +13 or47,XX, +13 • serious eye, brain, circulatory defects as well as cleft palate children rarely live more than a few months

  6. C. Edward's syndrome (trisomy 18):47, XX, +18 or 47, XY, +18 • almost every organ system affected • children with full Trisomy 18 generally do not live more than a few months.

  7. Disorders Caused by Nondisjunction of Sex Chromosomes • Can be fatal, but many people have these karyotypes and are just fine!

  8. D. Monosomy X (Turner's syndrome): 45, XO • the only viable monosomy in humans • genetically female, however, they do not mature sexually during puberty and are sterile. • Short stature and normal intelligence. (98% of these fetuses die before birth)

  9. E.Klinefelter’s Syndrome: 47, XXY • genetically male • individuals have male sex organs, but usually small testes and are sterile • may have breast enlargement and other feminine body characteristics. • Normal intelligence

  10. F. Trisomic Females: 47, XXX • healthy and fertile - usually • cannot be distinguished from • normal female except by karyotype • XYY Males: 47, XYY • Individuals are somewhat • taller than average and • sometimes have below • normal intelligence. • Increased amounts of acne • Normal sexual development

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