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12. Tay-Sachs disease (TSD) is an inborn error of metabolism that results in dea

ID: 145264 • Letter: 1

Question

12. Tay-Sachs disease (TSD) is an inborn error of metabolism that results in death, often by the age of two. You are a genetic counselor and interview a phenotypically normal couple about to have children You construct the following pedigree of their families. Assume that this trait is very rare. 1-1 IV-1 Name A. Using T for the functional allele and t for the disease causing allele, give the genotypes of the following individuals from the pedigree (2 points each): 1. I-I 2. 1-2 B. Calculate the probability that both the male and female are carriers for TSD 6 points). C. Calculate the probability that II-1 and III-2 have a second child with TSD (4 points)

Explanation / Answer

ANSWER 12.
Answer A.
Since the disease depicts a recessive pattern, hence every affected offspring will have both parents as at-least carriers (if not affected individuals), also, each affected individual will make all of its offsprings at least carriers (if not affected individuals)

Answer 1.
I-1 = Tt

Answer 2.
I-2 = Tt

Answer 3.
II-3 = tt

Answer 4.
III-1 = Tt