Solutions For An Introduction to Genetic Analysis Chapter 2 Problem 42P

The clue given about the disease is that it is a rare blood disease and the pedigree given is as follows:

1. If we think the disease is recessive, the father should be homozygous, as he is having the disease, and the mother should be heterozygous for the particular allele, for their children to get the disease.

2. If we think the disease is dominant, then the father who is affected would be heterozygous for that allele and the mother is not having that allele. The children who receive the allele, which is responsible for the disease, will express the disease.

Since no other information is given about heterozygosity of the mother, it is more likely to assume that the gene is dominant.