 |  | Rudolph's Pediatrics Section 11. Inherited Disorders of Metabolism > Part 2. Disorders of Amino Acid (AA) and Organic Acid (OA) Metabolism > Chapter 135. Hyperphenylal-AninemiasHyperphenylal-Aninemias: IntroductionBernd Christian Schwahn | |
Topics Discussed: genetics and dysmorphology; hyperphenylalaninemia; phenylketonuria, maternal.
Sections: References.
Excerpt:"Hyperphenylalaninemias are an important group of metabolic disorders
that present mainly as chronic encephalopathy. Severe hyperphenylalaninemia
leading to phenylketonuria (PKU) has a very distinct role in the
field of inherited metabolic disorders: PKU is the first genetic
disease that could be treated exclusively by dietary manipulation
and that could be entirely prevented by universal newborn screening
and presymptomatic dietary intervention. This has had a huge impact
on pediatric medicine, on the evolution of neonatal mass screening,
and on the concept of gene-environment interaction. Genetic defects
associated with hyperphenylalaninemia can now be regarded as a strong
risk factor for neurodisability, but their outcome is more determined
by the degree of metabolic control than by genetic variability.There is a continuous clinical spectrum of severity that ranges
from malformation and mental retardation to asymptomatic mild hyperphenylalaninemia.
Symptoms depend on the extent and ontogenetic timing of an organism's
exposure to elevated phenylalanine concentrations. The phenylalanine
pool is a function of dietary phenylalanine intake and residual
capacity for catabolism. Primary prevention of maternal PKU syndrome in newborns starts
with early advice about avoiding pregnancy in teenage girls with
hyperphenylalaninemia. Pregnancy prevention is mandatory in every
sexually active woman whose plasma phenylalanine concentrations
exceed 10 mg/dl (600
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