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 or 47,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