Question

Tay-Sachs disease is a lethal, autosomal recessive genetic disorder. If both parents are heterozygous carriers of the disease, what are the chances of them having a child who is also a heterozygous carrier for Tay-Sachs?
a. 100%b. 75%c. 50%d. 25%

Answer 1

Answer:

50%

Explanation:

Let's assume that the allele "T" gives the normal phenotype while the recessive allele "t" imparts the disease and is lethal in homozygous condition. The genotype of each of the two carrier parents would be "Tt". A cross between Tt and Tt would give the progeny in the following genotype ratio=

Tt x Tt= 1/4 TT: 1/2 Tt: 1/4 tt

Therefore, 1/2 or 50% progeny would be the carrier for the Tay-Sachs disease.