When Wendy was a baby, she was diagnosed with a gene-linked abnormality that left her unable to metabolize an important amino acid. Because her condition was diagnosed early, the doctors recommended that her parents put her on a diet that prevents an excess accumulation of the concerned amino acid in her body. This diet has helped her deal with the disorder successfully without experiencing any of the major disturbances of development this disorder is associated with. Wendy is likely to be suffering from .

Phenylketonuria

Explanation:

Phenylketonuria (PKU) is a type of a rare inherited metabolic disorder.  

Etiology: PKU results from excessive accumulation of the amino acid phenylalanine in the body. Normally, phenylalanine will be converted to tyrosine (forms neurotransmitters) by the action of the enzyme phenylalanine hydroxylase.

Among people with PKU, a defect in the PAH gene which codes to synthesize this enzyme occurs which leads to the absence of this enzyme. So the phenylalanine which is normally present in dietary protein is not metabolized and gets accumulated. This gene is inherited by the child only if both the parents are with the defective PAH gene.

Symptoms: Stunted growth, behaviroral disturbances, learning difficulties, seizures, tremors etc.

Treatment: Basic treatment is to follow a diet which limits dietary sources of phenylalanine. High protein foods like meat, egg should be avoided. Children can be given PKU formula to supplement their nutritional needs.