<Tr> <Th> Frequency </Th> <Td> ~ 1 in 12,000 newborns </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> <P> Treatment is with a diet low in foods that contain phenylalanine and special supplements . Babies should use a special formula . The diet should begin as soon as possible after birth and be continued for at least 10 years, if not lifelong . People who are diagnosed early and maintain a strict diet can have normal health and a normal life span . Effectiveness is monitored through periodic blood tests . The medication sapropterin dihydrochloride may be useful in some . </P>

Phenylketonuria (pku) a human disease characterized by mental retardation results from the
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