Question

If the phenotype followed in Pedigree 3 is X-linked recessive, then what is the genotype of II-2? Assume no new mutations and complete penetrance.

a. Homozygous dominant
b. Heterozygous
c. Homozygous recessive
d. Hemizygous dominant
e. Hemizygous recessive

Answer 1

Option (c), Given the X-linked recessive inheritance pattern, individual II-2 in the pedigree, if not expressing the recessive phenotype, is likely to have a heterozygous genotype, meaning one normal and one mutated allele on her X chromosomes.

Step-by-step explanation:

If the phenotype followed in Pedigree 3 is X-linked recessive, then the genotype of individual II-2 can be determined by understanding X-linked inheritance patterns. In X-linked recessive inheritance, a female (XX) can either be a carrier if she has one affected X chromosome (Xheterozygous) or affected if both her X chromosomes carry the recessive trait (Xhomozygous recessive). A carrier female would not express the trait because the X-linked recessive allele's effect is masked by the presence of a normal allele on her other X chromosome.

Assuming individual II-2 does not express the X-linked recessive phenotype, and no new mutations have occurred, she would most likely be heterozygous, meaning she carries one normal and one mutated allele. However, without specific information about the pedigree's individuals and their phenotypes, this answer makes some assumptions.