A. Limit intake of substrate for the enzyme.
B. Provide the deficient amino- acid.
C. Correct the enzyme defect.
D. Symptomatic management.
The disorder shown in the picture above represents Phenylketonuria as the child is showing features of microcephaly, blonde hair.
- The goal of therapy is to reduce phenylalanine in the body; formulas low in or free of this amino acid acid are available commercially.
- The diet should be started as soon as diagnosis is established.
- It is generally accepted that infants with persistent plasma levels of phenylalanine > 6 mg/ dL (360 mole /L) should be treated with a phenylalaninerestricted diet similar to that for classic PKU.
- No dietary restriction is currently recommended for infants whose phenylalanine levels are between 2 and 6 mg/dL. Plasma concentrations of phenylalanine in treated patients should be maintained as close to normal as possible.
- The duration of diet therapy is also controversial. Discontinuation of therapy, even in adulthood, may cause deterioration of IQ and cognitive performance. The current recommendation is that all patients be kept on a phenylalaninerestricted diet for life.
- Oral administration of the cofactor tetrahydrobiopterin (BH,) to patients with milder forms of hyperphenylalaninemia due to phenylalanine hydroxylase deficiency may reduce plasma levels of phenylalanine without the need to remain on a low phenylalanine diet. Significant reduction in plasma phenylalanine levels (>30%) also has been observed in some patients with classic PKU following administration of a single dose of oral BI-1, (10 mg/ kg).