The Incidence of Tay- Sachs, an Autosomal Recessive Genetic Disorder

Multiple Choice

The incidence of Tay- Sachs, an autosomal recessive genetic disorder, is approximately 1 in 3,500 in a certain population of Ashkenazi Jews. Assuming that this population is in Hardy- Weinberg equilibrium, what is the probability that a phenotypically normal female, with no family history, and a phenotypically normal male, who had an affected sister, will have a child with Tay- Sachs?

A) 1.96%
B) 0.028%
C) 0.55%
D) 2.2%
E) 0.49%