Progresses to severe ketoacidosis and death. If survives the neonatal period, mental retardation and neurologic impairment develop. Milder form also exists. If untreated, patients present in early months to years with alopecia, skin rashes, fungal skin infections, seizures, developmental delay, hypotonia, ataxia, hearing deficit, and visual abnormalities. Organic aciduria and ketoacidosis can occur later.
Affected newborns have elevated levels.
Second test is usually requested in 2 weeks if first positive. If second test positive, infant referred for sweat test for definitive diagnosis. Some recommend combination of IRT, sweat test and genetic mutation analysis for primary or recall testing. Gene amplification by polymerase chain reaction and hybridization with specific gene probes allows for application of DNA analysis to blood filter paper specimen - could result in confirmatory testing for PKU and other genetic disorders. J Pediatr .