Interestingly, only metabolites of the valine pathway have been detected in plasma and urine of patients with ECHS1 deficiency (ECHS1D), suggesting that ECHS1 is vital for valine metabolism, but not leucine or isoleucine metabolism [16,17]. This evidence concerns the gene ECHS1 and mitochondrial short-chain Enoyl-Coa hydratase 1 deficiency.