Albinism in humans is inherited as a simple recessive trait

Albinism in humans is inherited as a simple recessive trait. For the following families, determine the most likely genotypes of the parents. A normal male and an albino female have six children, three normal and three albino. What are the most likely genotypes of the parents?

a.male AA; female aa

b.male AA; female Aa

c.male Aa; female aa

d.male Aa; female Aa

Solution

c.male Aa; female aa

Albinism is a homozygous recessive trait. Assume that the gene coding for normal phenotype is A and the gene coding for albinism is a (A is normal and A is dominant over a), albinism is inherited by a homozygous recessive pattern (aa).

It is given that an unaffected male and an affected female had both normal and affected children. Means, the children receive one recessive allele from the mother and the other from the father. Thus, the father is heterozygous (Aa) and the mother is homozygous recessive (aa).