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 require an individual to take a larger than average dose of the drug to get the desired effect? (Note: The genotype of SNP 1 is listed first, followed by that of SNP 2.)
A) GG, AA
B) GG, AG
C) GC, AA
D) GC, AG
E) GC, GG

Question

Quizplus · Accepted Answer

Individuals with GG at SNP 1 break down the drug faster, requiring a larger dose to maintain efficacy. AG at SNP 2 does not slow down the breakdown as much as AA, so the faster breakdown effect of GG is not fully canceled out, leading to a need for a larger dose.

A Hypothetical Drug Has a Side Effect of Increasing Blood