Test Bank For Medical Genetics 5th Edition by Lynn B. Jorde, John C. Carey, Michael J. Bamshad (ALL CHAPTERS COVERED)

Test Bank For Medical Genetics 5th Edition by Lynn B. Jorde, John C. Carey, Michael J. Bamshad (ALL CHAPTERS COVERED) Chapter 1: Background and History Sample Problems & Essay Questions Question 1: Your class, which has 100 individuals, has been typed for a locus that has three possible alleles, labeled 1, 2, and 3. The genotypes and their counts are: 1,1 10 1,2 5 1,3 15 2,2 20 2,3 20 3,3 30 Based on these genotype counts, which is the gene frequency of allele 1? Answer: 20+5+15 = 40 = 0.2 200 200 Question 2: If an X-linked recessive disorder affects approximately 1/1,000,000 females (all homozygotes) in a population, what is the expected frequency of affected males in the population? Answer: q= √(1/1,000,000) = 1/1,000 Question 3: Two individuals who both have achondroplasia (autosomal dominant disorder) mate. What is the occurrence risk for this disorder in their offspring? Answer: 0.75 Question 4: Suppose that you have done a carrier test for PKU (autosomal recessive disorder) in a population, and you discover that the heterozygote carrier frequency is 1/500. Based on this information, what proportion of the population will be affected with PKU? (Note: your answer does not have to be exact.). Answer: 2pq=1/500 2q=1/500 q=1/1000 q2=1/1,000,000 Question 5: A woman with an X-linked dominant disorder mates with a phenotypically normal male. On average, what proportion of this couple's daughters will be affected with the disorder? Answer: 0.50 Question 6: A woman who is a heterozygous carrier of an X-linked recessive disease gene mates with a phenotypically normal male. The disease gene has a penetrance of Sample Problems & Essay Questions 2 80%. On average, what proportion of this couple's sons will be affected with the disorder? Answer: 0.8 x 0.5 = 0.4