he delta 32 mutation/deletion in the CCR5 gene (hereon called CCR5-delta32) offe
ID: 61725 • Letter: H
Question
he delta 32 mutation/deletion in the CCR5 gene (hereon called CCR5-delta32) offers resistance to HIV. Individuals homozygous for this allele are exceptionally resistant to HIV infection. Individuals heterozygous, with one copy of CCR5-delta32 and one normal CCR5 allele have partial resistance to HIV. Individuals homozygous for the normal CCR5 allele have no resistance HIV infection. The increased frequencies of the CCR5-delta32 allele in some European populations may be a result of its similar resistant effects to certain diseases experienced during the numerous plagues in European cities and towns. Having this allele increased odds of survival.
We will use R1 to designate the normal CCR5 allele, and R2 to represent the CCR5-delta32.
The scene: England, in the Middle Ages. Alistair, a plague survivor from a large town, is homozygous for CCR5-delta32. He moves to a small town unaffected by plague, and marries Elizabeth. Elizabeth is homozygous for the normal CCR5 allele.
A child between them has what chance of having partial resistance?
Complete a Punnett square on your own paper to solve this problem.
0 (0%)
1/2 (50%)
3/4 (75%)
1 (100%)
Explanation / Answer
Alistair: homozygous for CCR5-delta32 (R2R2)
Elizabeth: homozygous for the normal CCR5 allele (R1R1)
R1R1 x R2R2
From the puinnett square it can be known that all children produced would be heterozygous having genotype R1R2 and posess partial resistance to HIV. A child between them has 1 or 100% chance of having partial resistance.
male/ female R2 R2 R1 R1R2 R1R2 R1 R1R2 R1R2Related Questions
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