Human genetic disorders

1. Human genetic disorders Donald Winslow 1 March 2011 References: Hoefnagels, Marïelle. 2009. Biology, 1st ed., McGraw-Hill, NY; Ch. 10 pp 201, 204-205, 208; Ch. 11 pp 215, 220-226 Mader, Sylvia S. 2008. Biology, 9th ed., McGraw-Hill, NY; Ch. 11 pp 192-196; Ch 12. pp 204-207 Mader, Sylvia S. 2011. Inquiry into Life, 13th ed., McGraw-Hill, NY; Ch. 23 pp 478-481, Ch. 24 pp 488-497

2. Objectives • Describe & give specific examples of human genetic disorders that are: • Autosomal dominant • Autosomal recessive • Incompletely dominant • X-linked recessive

3. Autosomal dominant disorders • Huntington’s disease • Progressive neurological degeneration • Eventually fatal • Symptoms start late in life • Marfan syndrome • Defect in elastic connective tissue protein • Dislocated lens, long limbs, weak aorta

4. Autosomal recessive disorders • Tay-sachs disease • Within first year development slows down • Leads to severe seizures and paralysis • Cystic fibrosis • Respiratory disease • Mutation in protein affects ion transport • Mucus builds up in lungs

5. Incomplete dominance • Familial hypercholesterolemia • High blood cholesterol • Cholesterol deposits accumulate on fingers • Sickle-cell anemia • Homozygote has severe blood disease • Heterozygote carrier mostly healthy • Carrier resistant to malaria • Prevalent in tropical countries

6. X-linked recessive disorders • Hemophilia • Blood does not clot well • Prevalent in royal families of Europe • Red-green color blindness • Duchenne muscular dystrophy • Muscles degenerate • Fragile X syndrome • Can cause mental impairment or autism

7. Practice Punnett squares & pedigrees!