Assume that one child in 2500 is born with phenylketonuria a

Assume that one child in 2500 is born with phenylketonuria (an inability to metabolize the amino acid phenylalanine). This is known to be a recessive autosomal trait.

What proportion of the population would be able to metabolize phenylalanine?

Solution

Let P is the normal allele & p is the phenylketonuria allele (recessive) . The frequency of homozygous pp individuals in the population is then equal to q2, which is 1/2,500. The frequency of the p allele is the square root of 1/2,500 1/50 or 2%.therefore 98% population would be able to metabolize phenylalanine.