2. Pedigree definition  Pedigree: a family history that shows how a trait is inherited over several generations  Pedigrees are usually used when parents want to know if they are carriers of a particular disorder

3. Making a Pedigree  Female  Male  Married Couple  Siblings Filled in symbols indicate individual is affected with a disorder

4. How do you read a pedigree chart? A shape that is not shaded indicates that the person does NOT have the trait. A shape that is half-shaded indicates that the person is a “carrier” (has 1 allele). A shape that is completely-shaded indicates that the person has the trait

5. Example of a Pedigree You Parents Aunts, Uncles Grandparents Brother Do any disorders run in this family??

6. Interpreting a Pedigree  What can you tell from a pedigree?  Whether a family has an autosomal or sex-linked disease or disorder  Autosomal disorder: appears in both sexes equally  Sex-linked disorder: allele is located only on the X or Y chromosome. Most sex-linked genes are on the X chromosome and are recessive  So who would have an X-linked disorder more often, boys or girls?  Whether a disorder is dominant or recessive

7. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Sex Linked! (in this case allele is recessive and located on the X chromosome)

8. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Autosomal dominant!

9. Is this disorder 1) autosomal or sex linked, 2) dominant or recessive? You Parents Aunts, Uncles Grandparents Brother Autosomal recessive!

10. More Practice  http://highered.mheducation.com/sites/0072 485949/student_view0/chapter3/interactive_ activity.html http://highered.mheducation.com/sites/0072 485949/student_view0/chapter3/interactive_ activity.html

11.  Sex Chromosomes: one of the two chromosomes that determine an individual’s sex (XX=female, XY=male)  Autosomal Chromosomes: chromosome that is not a sex chromosome  Sex-linked gene: gene located on a sex chromosome

12. Common Genetic Disorders  Color blindness  Sickle cell anemia  Cystic Fibrosis  Hemophilia  Huntington’s Disease For more info, go to: http://www.ncbi.nlm.nih.gov/pubmedhealth/

13. Color Blindness  Deficiency to perceive colors  Problem with color- sensing pigments in certain nerve cells of the eye  About 1 in 10 men have some form of color blindness.  Sex-linked disorder

14. Sickle Cell Anemia  Disorder where abnormal hemoglobin (a protein inside red blood cells) is produced and warps red blood cells  Sickle cells deliver less oxygen to body’s tissues and can get stuck in small blood vessels  Tends to be seen in people of African or Mediterranean descent  Recessive trait

15. Cystic Fibrosis  Life threatening, causes thick mucus to build up in various areas of the body (lungs, digestive tract, etc).  Tends to run in Caucasians, of Northern/Central European descent (1 in 29 Americans carry the allele)  Recessive, autosomal disease  Average life span in US for people with CF is 37, death usually caused by lung complications

16. Hemophilia  Bleeding disorder, where it takes a long time for blood to clot (body lacks proteins involved in clotting)  Treatment involves injection with missing clotting protein  Sex-linked (carried on the X chromosome)

17. Huntington’s Disease  Deterioration of brain tissue, usually begins between age 30 and 40.  No cure, but have medications to cope with symptoms  People usually die 15-20 years after onset of degeneration  Autosomal, dominant

18. Chromosomal Disorders  Nondisjunction: error in meiosis in which the homologous chromosomes fail to separate properly  If nondisjunction occurs during meiosis, gametes with an abnormal number of chromosomes may result, leading to a disorder of chromosome numbers.

20.  Examples of nondisjunction:  Trisomy: three copies of a chromosome  Trisomy 21: Down Syndrome (characterized by mild to severe mental retardation)  Turner’s Syndrome: Nondisjunction of the X chromosomes. Females usually only inherits one X chromosome. Women are sterile.  Klinefelter’s Syndrome: males inherit an extra X chromosome. Males are sterile.

21. Karyotype  A karyotype shows the complete diploid set of chromosomes grouped together in pairs, arranged in order of decreasing size.