PATHOLOGY

Detailed explanation-1: -Autosomal recessive inheritance pattern You get one from each parent. Their health is rarely affected because they have only one changed gene. Two carriers have a 25% chance of having an unaffected child with two unaffected genes. They have a 50% chance of having an unaffected child who also is a carrier.

Detailed explanation-2: -Conversely, there also is a 25% chance that the carrier parents will both pass along the mutated gene, causing the child to have PKU. However, there is a 50% chance that a child will inherit one normal gene from one parent and one abnormal one from the other, making the child a carrier.

Detailed explanation-3: -When both parents are carriers of the faulty PKU gene, their child will be born with PKU if they receive one copy of the faulty gene from each parent. When both parents are carriers, the possibilities in each pregnancy are: 1 in 4 chance of having an affected child. 2 in 4 chance of having a child that is a carrier.

Detailed explanation-4: -Classical PKU is an autosomal recessive disorder, caused by mutations in both alleles of the gene for phenylalanine hydroxylase (PAH), found on chromosome 12. In the body, phenylalanine hydroxylase converts the amino acid phenylalanine to tyrosine, another amino acid.