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Title: Very simple question about sex-linked traits Post by: bruin on Mar 21, 2015 I am reading Behavioral Genetics by Plomin et al and it contains this statement:
"[Red-Green] color blindness is caused by a recessive allele on the X chromosome...An unaffected mother and color-blind father have unaffected offspring, but daughters have sons with 50 percent risk for color blindness." However, I feel that this is incorrect as a blanket statement. It seems to me that it should say that this is true of the offspring of homozygous dominant mothers and color-blind fathers, not of "unaffected" mothers and color-blind fathers. Am I correct? Is this a slip-up by the authors? Title: Re: Very simple question about sex-linked traits Post by: bio_man on Mar 21, 2015 They don't mention the mother being a carrier, so that's what I'm assuming they mean by unaffected.
Title: Re: Very simple question about sex-linked traits Post by: bruin on Mar 21, 2015 Thanks bio man. I'm not that familiar with the terminology - "unaffected" sounded to me like a reference to phenotype. (I probably should have seen that if "unaffected" meant phenotype, then for a recessive sex-linked trait like color blindness, there would be no such thing as an "affected" female - rendering the term "unaffected" redundant).
Title: Re: Very simple question about sex-linked traits Post by: bio_man on Mar 22, 2015 (I probably should have seen that if "unaffected" meant phenotype, then for a recessive sex-linked trait like color blindness, there would be no such thing as an "affected" female - rendering the term "unaffected" redundant). I suppose. I hope that cleared things up. Let me know if you need anything else. |