Answer: D - The Guthrie test is a blood assay used to diagnose phenylketonuria in newborn infants. It detects bacterial growth in an agar culture that is due to the presence of excess phenylalanine.
Phenylketonuria (PKU) is a rare inherited disorder that causes an amino acid called phenylalanine to build up in the body. It is typically diagnosed in newborn infants through a screening test called the newborn screening test, which is done shortly after birth. This test involves collecting a small blood sample from the infant's heel and sending it to a laboratory for analysis.
If the newborn screening test indicates that the infant may have PKU, a confirmatory test will be performed to confirm the diagnosis. This may involve collecting another blood sample or performing a genetic test to look for mutations in the gene responsible for making the enzyme needed to break down phenylalanine.
PKU can cause serious health problems if left untreated, including intellectual disability and problems with brain development. Therefore, it is essential to diagnose PKU as early as possible so treatment can begin as soon as possible. Treatment for PKU involves following a special diet low in phenylalanine, which can help prevent the build-up of this amino acid in the body and allow for normal brain development.
