In the following pedigree,the indicated trait is caused by which type of allele? Assume the trait is fully penetrant and that the trait is rare in the population,so that alleles for the trait are not carried by anyone who is not the progeny of a mating shown in the pedigree.
A) autosomal recessive
B) Y-linked dominant
C) X-linked recessive
D) X-linked dominant
E) Y-linked recessive

Question

In the following pedigree,the indicated trait is caused by which type of allele? Assume the trait is fully penetrant and that the trait is rare in the population,so that alleles for the trait are not carried by anyone who is not the progeny of a mating shown in the pedigree. 
A) autosomal recessive 
B) Y-linked dominant 
C) X-linked recessive 
D) X-linked dominant 
E) Y-linked recessive

Quizplus · Accepted Answer

The indicated trait is seen in both males and females, which rules out Y-linked inheritance. The presence of affected fathers passing the trait to both sons and daughters rules out autosomal recessive inheritance, as affected individuals would need to be homozygous for the trait and therefore have affected parents. X-linked dominant inheritance fits the inheritance pattern seen in the pedigree, as affected fathers pass the trait to all their daughters (who would be obligate carriers) and half their sons (who would be affected).

In the Following Pedigree,the Indicated Trait Is Caused by Which