Human Chromosome Disorders

1. Human Chromosome Disorders PLEASE be respectful of the afflicted people shown in this powerpoint. One little mistake in meiosis and this could have been YOU!

2. DEFINITIONS KARYOTYPE: a picture of the chromosomes. http://learn.genetics.utah.edu/content/begin/traits/karyotype/

3. AUTOSOME OR AUTOSOMAL CHROMOSOME: A chromosomethat is not a sex chromosome For humans, chromosomes 1 - 22 SEX CHROMOSOME: those chromosomes that determine the sex of the individual: The x and y.

4. HUMAN KARYOTYPE (Know this) NORMAL Is person male or female? How do you know?

5. NORMAL Is person male or female? How do you know?

6. Nondisjunction occurs when either HOMOLOGOUS CHROMOSOMES fail to separateduring anaphase I of meiosis, or SISTER CHROMATIDS FAIL TO SEPARATE during anaphase II. Result: one gamete has 2 copies of one chromosome and the other has NO copy of that chromosome. (The other chromosomes are normal)

7. There are only 3 kinds of trisomies* that result in babies that can survive: • Down’s syndrome = trisomy 21 • 2. Patau syndrome = trisomy 13 • 3. Edward’s syndrome = trisomy 18 • * For trisomies of the autosomal chromosomes.

8. Down’s syndrome = trisomy 21

9. Down syndrome affects 1:700 children. MOST COMMON. Characteristic facial features, short stature; heart defects, respiratory disease, shorter lifespan, 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.

10. Patau Syndrome = trisomy 13

11. Patau Syndrome = trisomy 13 (1 in 5,000 live births) Serious eye, brain, circulatory defects as well as cleft palate. Children rarely live more than a few months. Rare to get into twenties.

12. Edward’s syndrome = trisomy 18

13. Edward’s Syndrome = trisomy 18 ( 1 in 3,000 live births) Almost every organ system affected. Usually, moms carrying babies with Edward’s suffer miscarriages. Generally do not live more than a few months. Severe intellectual disability and abnormalities in many parts of the body. Individuals with trisomy 18 often have a low birth weight; a small, abnormally shaped head; a small jaw and mouth; clenched fists with overlapping fingers; heart defects; and abnormalities of other organs.

14. Chromosome abnormalities involving the sex chromosomes http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/flash/trisomy.swf

15. TURNER’S SYNDROME: missing one x chromosome: non-disjunction in a pair of sex chromosomes. Turner syndrome is caused by a missing X chromosome. Child is female: XO EVERY cell of the baby’s body is XO. The genes affected are involved in growth and sexual development, which is why girls with the disorder are shorter than normal and have abnormal sexual characteristics.

16. Klinefelter syndrome: XXY one of the most common genetic abnormalities. It affects between 1 in 500 and 1 in 1,000 males. Many people with this disorder have no idea they have it until they hit puberty or try to have children. At puberty, men with this syndrome often develop more breast tissue than normal, have a less muscular body, and grow very little facial or body hair. When men with Klinefelter syndrome try to have children, most discover that they are sterile because they cannot produce sperm. Learning disabilities (not categorized as mental retardation) are also a common problem for them. Can be treated with testosterone

17. Comprehension check http://learn.genetics.utah.edu/content/begin/traits/predictdisorder/

18. CAREERS IN GENETIC COUNSELING Genetic counselors are health professionals who are trained to help families understand genetic disorders and to provide information and support to those families. They may also serve as patient advocates by referring individuals or families to local services that can be of assistance. http://learn.genetics.utah.edu/content/disorders/