Which of the following is a feature of Phenylketonuria?

Phenylketonuria: - Phenylketonuria (PKU) is the most common metabolic disorder in amino acid metabolism. The incidence of PKU is 1 in 10,000 bihs. It is due to the deficiency of the hepatic enzyme, phenylalanine hydroxylase, caused by an autosomal recessive gene Phenylalanine metabolism in PKU: Phenylketonuria primarily causes the accumulation of phenylalanine in tissues and blood, and results in its increased excretion in urine Metabolites are excreted in urine in high concentration in PKU. Phenylacetate gives the urine a mousey odour Accumulation of phenylalanine in brain impairs the transpo and metabolism of other aromatic amino acids (tryptophan and tyrosine) leading to Mental retardation, failure to walk or talk, failure of growth, seizures and tremors ret he characteristic findings in PKU. If untreated, the patients how very low IQ (below 50). Accumulation of phenylalanine competitively inhibits tyrosinase and impairs melanin formation. The result is hypopigmentation that causes light skin colour, fair hair, blue eyes etc Diagnosis of PKU was detected by screening the new-born babies for the increased plasma levels of phenylalanine (PKU, 20-65 mg/dl; normal 1-2mg/dl). This was carried out by Guthrie test, which is a bacterial (Bacillus subtilis) bioassay for phenylalanine. Phenylpyruvate in urine can be detected by ferric chloride test (a green colour is obtained). Method of Choice is Tandem Mass Spectrometry, also for all the Inborn metabolic Error disease.