A newborn diagnosed with phenylketonuria (PKU) due to phenylalanine hydroxylase deficiency is placed on a phenylalanine-restricted diet. In classic PKU, which metabolites accumulate and are responsible for the musty/mousy body odor?
- A Homogentisic acid and fumarylacetoacetate
- B Succinylacetone and delta-aminolevulinic acid
- C Phenylpyruvate and phenylacetate ✓
- D Methylmalonic acid and propionate
Correct answer: C. Phenylpyruvate and phenylacetate
Explanation
When phenylalanine hydroxylase is absent, excess phenylalanine is transaminated to phenylpyruvate (a phenylketone) and further metabolized to phenylacetate and phenyllactate. Phenylacetate is excreted in urine and sweat, imparting the characteristic musty or mousy odor. Homogentisic acid accumulation occurs in alkaptonuria. Succinylacetone accumulates in tyrosinemia type I. Methylmalonic acid accumulates in methylmalonic acidemia.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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