Phenylketonuria (PKU) is an autosomal recessive metabolic genetic disorder characterized by a mutation in the gene for the hepatic enzyme phenylalanine hydroxylase (PAH), rendering it nonfunctional.
The Guthrie test, also known as the Guthrie bacterial inhibition assay, is a medical dried blood spot screening test performed by heel prick on newborn infants to detect various conditions like
- phenylketonuria ,
- congenital hypothyroidism,
- sickle-cell disease,
- cystic fibrosis and
- Medium Chain Acyl CoA Dehydrogenase Deficiency (MCADD).
In recent years it is gradually being replaced in many areas by newer techniques such as tandem mass spectrometry (TMS)
Neonatal screening - TMS
Features of PKU
- Mental Retardation
- Musty / Mousy odor to Sweat and Urine (because of phenylacetate)
- Tyrosine Supplementation
- Phenylalanine Restriction (Aim in serum < 6 mg/dl ) Important - DO NOT completely stop phenylalanine
Q. Non essential Amino Acid that becomes essential in PKU is ?