<Tr> <Th> Frequency </Th> <Td> ~ 1 in 12,000 newborns </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Phenylketonuria (PKU) is an inborn error of metabolism that results in decreased metabolism of the amino acid phenylalanine . Untreated PKU can lead to intellectual disability, seizures, behavioral problems, and mental disorders . It may also result in a musty smell and lighter skin . Babies born to mothers who have poorly treated PKU may have heart problems, a small head, and low birth weight . </P> <P> Phenylketonuria is a genetic disorder inherited from a person's parents . It is due to mutations in the PAH gene which results in low levels of the enzyme phenylalanine hydroxylase . This results in the buildup of dietary phenylalanine to potentially toxic levels . It is autosomal recessive meaning that both copies of the gene must be mutated for the condition to develop . There are two main types, classic PKU and variant PKU, depending on if any enzyme function remains . Those with one copy of a mutated gene typically do not have symptoms . Many countries have newborn screening programs for the disease . </P>

Phenylketonuria (pku) is a genetic disorder in which
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