Phenylketonuria (PKU) is an inherited metabolic disorder caused by an autosomal recessive allele.
Two parents are heterozygous for PKU.
Describe the genetic cross of these parents. Use P P\,P for the dominant normal allele and p p\,p for the recessive PKU allele, identifying parental genotypes, their gametes, and the possible offspring genotypes. State the ratio of offspring without PKU to offspring with PKU.
Calculate the probability of these parents producing a female child with PKU.
In a certain country, the probability of a newborn being born with PKU is 0.000125. There are approximately 640,000 640,000\,640,000 births per year in this country. Calculate the number of children born per year who are expected to have PKU. Show your working.
