Case Study: The Genetics of Resistance to HIV Infection

CCR5 Genotype Test
Here are the results of testing the CCR5 gene in three individuals: an EU man, one of his parents, and a control individual (not necessarily in that order).

Use the results to determine each person’s genotype. Then determine which one is EU.

INSTRUCTIONS:
First, determine the correct genotype for the individuals.

Then select which individual is EU.

Graphic: Genotype Test Results


Selected Answer: Option A

Incorrect.

The wildtype allele, called CCR5, is larger than the mutant allele, called CCR5Δ32. After electrophloresis, the larger DNA fragments are near the top and the smaller ones are near the bottom. A person who shows one type of band must be homozygous, with two of the same alleles. A person who shows both large and small bands must be heterozygous, with one of each allele.

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