A man and woman are each heterozygous for both Tays Sachs Ts

A man and woman are each heterozygous for both Tays Sachs (Ts) and phenylketonuria (PKU). Both conditions are autosomal recessive and assort independently. They plan to many and start a family. (Show your work) A. What proportion of the children of this couple will have neither condition? B. What proportion of the children will have either Ts or PKU but not both? C. What proportion of the children will be carriers (not affected but containing a mutant allele) of one or both conditions? Give the genotype of these individuals

Solution

A. Rr (Unaffected carrier father), Rr (Unaffected carrier mother)

Rr x Rr -------> RR, Rr, Rr, rr

75% of children will have neither condition

B. 25% of children have either Ts or PKU but will not have both

C. 50% of the children will be carriers where they will have a mutant allele. The genotype of these individuals are Rr