If both parents are carriers for PKU (recessive allele), there's a 25% chance of having an affected child (with PKU).
Phenylketonuria (PKU) is an autosomal recessive genetic disorder caused by mutations in the phenylalanine hydroxylase (PAH) gene.
Individuals with PKU cannot properly metabolize phenylalanine, leading to its accumulation in the blood, which can result in intellectual disabilities and other health issues.
When both parents are carriers of the PKU allele, there are several possible outcomes for their offspring.
The allele for PKU is typically represented as "p," and the normal allele as "P."
The possible combinations in their children are PP (normal), Pp (carrier), and pp (affected).
To determine the probability of each outcome, a Punnett square can be employed.
When two carriers (Pp) have children, there is a 25% chance of having a child with normal phenotypes (PP), a 50% chance of having a carrier (Pp) like the parents, and a 25% chance of having a child with PKU (pp).
The probabilities always sum to 1, reflecting the certainty that one of these outcomes will occur.
If both parents are carriers of the PKU allele, there is a 25% probability of having a child with PKU, underscoring the importance of genetic counseling to inform individuals about the risks and options associated with their carrier status.