A normal couple went to a genetic counselor to determine the

A normal couple went to a genetic counselor to determine their chances of having a child with galactosemia, an autosomal recessive disorder. The counselor told them that one of them is a carrier for galactosemia, but the other is not. What is the likelihood that their child will have galactosemia? Selected Answer: Answers A. There is no chance their child will have galactosemia B. Their child might be heterozygous for galactosemia, but not have the disorder C. There is a 50% chance that their child will be homozygous and will not carry the recessive allele. D. Two of the above answers are true E. A, B, and C are all true

Solution

Choice D is correct.

Reason: Galactosemia is an autosomal recessive metabolic disorder which means that in order to acquire the disease, the person must be homozygous for both the alleles of galactosemia. It can be clealry understood from the information given that only one of the parents is a carrier of this allele i.e. heterozygous for the allele. This means that neither of the parents is phenotypically affected from the disease. Similarly, the heterozygous parent will transfer this allele to his/her offspring and the offspring will be again heterozygous in nature. This clearly suggests that the offspring will be a carrier but not affected by the disease. (This means that option A and B are correct)