The Incidence of Phenylketonuria (PKU), an Autosomal Recessive Genetic Disorder

Multiple Choice

The incidence of phenylketonuria (PKU) , an autosomal recessive genetic disorder, is approximately 1 in 4,500 in Ireland. Assuming Hardy- Weinberg equilibrium, what is the probability that a phenotypically normal Irish female, with no family history, and a phenotypically normal Irish male, with an affected sister, will have a child with PKU?

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