Answer to Question #276314 in Genetics for question

Question

Albinism, the total lack of pigment, is due to a recessive gene. A man and woman plan to marry and wish to know the probability of their having any albino children. What are the probabilities if: 

1.     both are normally pigmented, but each has one albino parent. 

2.     the man is an albino, the girl is normal, but her father is an albino. 

3.     the man is an albino and the girl's family includes no albinos for at least three generations.

Answer 1

Albino is an autosomal recessive disorder and should be present in the homozygous state (aa) to express itself. Since normal parents have an albino child (aa), this means that both parents carry one copy of albino allele (a) and are the carrier for the disease. The heterozygous parents (Aa) will produce genotypic ratio 1 AA: 2Aa: 1 aa which makes that there is always ¼ possibility of their child to be albino. Since each time a couple can have ½ sons (XY) and ½ daughters (XX); therefore, the heterozygous couple will have ¼ x ½ = 1/8 possibility of their girl child to be albino. 

So, the correct answer is option C.