Which one of the following disorder shows symptoms of excess of phenylalanine in urine of humans?

Phenylketonuria is an inborn error of metabolism inherited as an autosomal recessive trait.

The affected individual lacks an enzyme called phenylalanine hydroxylase that converts the amino acid phenylalanine into tyrosine.

As a result, phenylalanine accumulates and gets converted into phenylpyruvic acid and other derivatives.

Accumulation of these in the brain results in mental retardation. These are also excreted through urine because of their poor absorption by the kidney.

Answer: Phenylketonuria