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Title
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Phenylketonuria
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ImagePath
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System
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amino acid metabolism − phenylalanine/tyrosine
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Overview
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AR deficiency of phenylalanine hydroxylase or BH₄ cofactor leading to ↑ Phe & ↓ Tyr.
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Pathophysiology
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Excess Phe competes with neutral AAs at BBB → impaired neurotransmitter synthesis & myelination.
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Presentation
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Intellectual disability, growth delay, seizures, fair complexion, eczema, musty body odor.
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Diagnosis
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Newborn screen (tandem MS) after protein feeding; ↑ Phe/Tyr ratio in plasma.
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Management
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Lifetime restriction of Phe (avoid aspartame) with Tyrosine supplementation; BH₄ (sapropterin).
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Epidemiology
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≈1 : 10 000 Caucasian births.
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Tags
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