Two Potential Parents Have the Mutated Gene
According to the Mayo Clinic "Most often, PKU is passed down the family tree by parents who are carriers of the disorder but don't know it." In a process of passing on genes to newborns called autosomal recessive pattern, the potential parents each carry one copy of the mutated gene without any signs or symptoms of the actual condition, called phenylketonuria. Why some individuals have this gene and others do not is not yet known.
Phenylketonuria is Inherited
The National Organization for Rare Disorders Inc. states that two individuals who are silent carriers of the gene that causes this condition conceive a child and the child is born with an enzyme deficiency. A PKU treatment center can perform a test on the potential parents to confirm if the gene is present. After delivery, a routine blood test can help to confirm a diagnosis in the infant.
You are Born with a Genetic Abnormality
You are born with a deficiency of an enzyme called phenylalanine hydroxylase. According to the National PKU news agency, "This enzyme normally converts the essential amino acid, phenylalanine, to another amino acid, tyrosine. Failure of the conversion to take place results in a buildup of phenylalanine." In other words, if you have PKU, your body can't process the protein called phenylalanine that is found in many foods. If not treated right away, this buildup can lead to brain damage and mental retardation.
You Fall Within the 25% Chance Range
The National PKU News organization says, "When two carriers conceive a child, there is a one in four chance for each pregnancy that the baby will have PKU. The incidence of carriers in the general population is approximately one in 50 people, but the chance that two carriers will mate is only one in 2,500."
