A hypothetical drug has a side effect of increasing blood pressure.Individuals who are homozygous for G at SNP 1 break down this drug faster than average.Individuals who are homozygous for A at SNP 2 break down this drug slower than average.The effects of these two SNPs roughly cancel each other out, such that homozygotes at both SNPs generally have average rates of breakdown of the enzyme.Which combination of genotypes is most likely to put an individual at risk for having the side effect? (Note: The genotype of SNP 1 is listed first, followed by that of SNP 2.)
A) GG, AA
B) GG, AG
C) CC, AA
D) GC, AG
E) GC, GG

Question

Quizplus · Accepted Answer

C) CC, AA genotype combination is most likely to put an individual at risk for having the side effect because individuals homozygous for G at SNP 1 break down the drug faster (thus CC would break it down slower) and individuals homozygous for A at SNP 2 break down the drug slower. This combination does not have the fast breakdown allele at SNP 1 and has the slow breakdown allele at SNP 2, leading to slower overall drug breakdown and increased risk of side effects.

A Hypothetical Drug Has a Side Effect of Increasing Blood