Fig. 1.

Acyl thioester metabolism and oxidative phosphorylation in brain mitochondria. The fatty acid β-oxidation pathway is shown only the last two steps. A cluster of four yellow balls represents 17β-HSD10. β-HBD rather than HAD or 17β-HSD10 plays a key role in ketone body metabolism. A missense mutation in the 17 β-HSD10 gene would block the isoleucine catabolic pathway to result in the accumulation of isoleucine metabolites such that tiglic acid and 2-methyl-3-hydroxybutyric acid would be released from the HSD10 deficienct-cell and their glucoronated derivatives be excreted in the urine of patient having an inborn error in isoleucine metabolism.