Question 1

If we assume that the average person carries one deleterious autosomal recessive mutation,what is the risk that the child of an uncle-niece mating will be homozygous for one of the mutations present in the parents of the child's father?

A) 1/64
B) 1/32
C) 1/16
D) 1/11
E) 1/8

1/16

Accepted Answer

The probability of the uncle and niece being carriers of the same deleterious allele is 1/16 (assuming they share one common ancestor who carried the mutation). The probability that the uncle and niece each pass on that same deleterious allele to their child is 1/4. Therefore, the probability of the child being homozygous for the deleterious allele is 1/16 x 1/4 = 1/64. But since there are potentially multiple deleterious alleles that could be inherited from the parents of the child's father, we need to consider each one independently. If we assume that each parent of the father carries one deleterious allele (for a total of 2 alleles), then the overall risk of the child being homozygous for at least one of those deleterious alleles is 2 x 1/64 = 1/32, which is closest to answer choice B. However, the question is specifically asking about the risk of the child being homozygous for one of the mutations presented in the parents of the child's father, so the correct answer is actually answer choice C (1/16).

Question 2

Which of the following should be a feature of genetic counseling sessions?&#10;A) A follow-up letter should be given to the consultand to help with information recall&#10;B) It should be nondirective&#10;C) Risk figures should be conveyed in a manner that gives them context&#10;D) Technical terms should be used sparingly and should be thoroughly defined&#10;E) All of the above

Accepted Answer

All of the above options should be included as features of genetic counseling sessions. A follow-up letter can help the consultand remember important information discussed during the session. The counseling session should be nondirective, meaning the counselor should not attempt to influence the consultand's decision-making process. Risk figures should be given in context, so the consultand can understand what they mean for their individual situation. Finally, technical terms should be used sparingly and clearly defined to ensure the consultand understands the information being presented.

Deck 17: Genetic Counseling