Question

(a) For each pedigree, indicate the most likely mode of inheritance (6 pts) (2 pts) (b) In pedigree B, circle all individuals who are heterozygous. or to 0 0 - 이 SSO | 호 co | or - TTT Choices: A. Y-linked, B. X-linked dominant C. recessive, D. Autosomal dominant, E. Autosomal recessive.

Answer 1

a)A. Recessive

The unaffected parents are having affected offspring, it can be assumed that the trait is recessive. In addition, the trait appears to affect males more than females which is a character of X linked recessiveness and rules out other chances.

B. Autosomal dominant.

Every affected person has at least one affected parent which makes it a dominant trait and shows a vertical pattern of inheritance in the pedigree. Generally, X-linked dominant traits tend to be milder in females than males.

C. Autosomal recessive

Only the autosomal recessive cases could skip generations in the pedigree chart. So that no other options are suitable here. The major character of autosomal recessiveness is skipping of the generations and unaffected parents can have affected children.

D. Y linked

A Y-linked trait would pass from an affected father to all of his sons, and then from them to their grandsons, etc. Since here the male is transferring the trait to his son, the case is Y linked.