Human genetic disorders Donald Winslow 1 March 2011 References: Hoefnagels, Marïelle Biology, 1st ed., McGraw-Hill, NY; Ch. 10 pp 201, , 208; Ch. 11 pp 215, Mader, Sylvia S Biology, 9th ed., McGraw-Hill, NY; Ch. 11 pp ; Ch 12. pp Mader, Sylvia S Inquiry into Life, 13 th ed., McGraw-Hill, NY; Ch. 23 pp , Ch. 24 pp

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

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

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

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

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

Practice Punnett squares & pedigrees!