Introduction to Genetic Analysis 63

Introduction to Genetic Analysis 63 - 44200_02_p27-72...

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62 Chapter 2 Patterns of Inheritance a. Deduce the most likely mode of inheritance. b. What would be the outcomes of the cousin mar- riages 1 3 9, 1 3 4, 2 3 3, and 2 3 8? Solution a. The most likely mode of inheritance is X-linked dom- inant. We assume that the disease phenotype is domi- nant because, after it has been introduced into the pedi- gree by the male in generation II, it appears in every generation. We assume that the phenotype is X-linked because fathers do not transmit it to their sons. If it were autosomal dominant, father-to-son transmission would be common. In theory, autosomal recessive could work, but it is improbable. In particular, note the marriages between af- fected members of the family and unaffected outsiders. If the condition were autosomal recessive, the only way in which these marriages could have affected off- spring is if each person marrying into the family were a heterozygote; then the matings would be a / a (af- fected) 3 A / a (unaffected). However, we are told that 4.
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This note was uploaded on 01/10/2011 for the course BIOL BIOL taught by Professor Johnson during the Spring '08 term at Aberystwyth University.

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