Human Genetics Problem Set

Problem 1: Inheritance of an X-linked recessive trait


Red-green color blindness is X-linked in humans. If a male is red-green color blind, and both parents have normal color vision, which of the male's grandparents is most likely to be red-green color blind?

A. maternal grandmother
B. maternal grandfather
In this problem, an X-linked recessive allele is passed from an affected male, to a daughter who is a heterozygous carrier, and subsequently to an affected grandson.
C. paternal grandmother
D. paternal grandfather
E. either grandfather is equally likely

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Revised: November 5, 1998
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