Child with a defect in leucine metabolism associated with beta-hydroxyisovaleric aciduria and beta-methylcrotonylglycinuria.

Child with a defect in leucine metabolism associated with p-hydroxyisovaleric aciduria and p-methylcrotonylglycinuria Three inborn errors of the leucine degradation pathway are known, maple syrup urine disease, isovaleric acidaemia, and ,B-methylcrotonylglycinuria. The latter was first described by Eldjarn and his colleagues in 1970 (Eldjarn et al., 1970; Stokke et al., 1972). The patient they reported excreted large amounts of fl-methyl- crotonylglycine and 3-hydroxyisovaleric acid, presumably due to a defective activity of the enzyme ,B-methylcrotonyl CoA carboxylase. A second child with these metabolites in his urine was described the following year (Gompertz et al., 1971). The clinical presentations of these two children were entirely different. The first suffered from a neurological condition similar to Werdnig-Hoffmann disease, while the second presented with vomiting and an acute metabolic acidosis and ketosis. In this report we describe a 9-month-old infant who was admitted moribund with an upper lobe pneumonia and was subsequently shown to be excreting these abnormal metabolites.