A critical reappraisal of dietary practices in methylmalonic acidemia raises concerns about the safety of medical foods. Part 2: cobalamin C deficiency

Cobalamin C (cblC) deficiency impairs the biosynthesis of 5′-deoxyadenosyl-adenosyl- and methyl-cobalamin, resulting in methylmalonic acidemia combined with hyperhomocysteinemia and hypomethioninemia. However, some patients with cblC deficiency are treated with medical foods, devoid of methionine and high in leucine content, that are formulated for patients with isolated propionate oxidative defects. We examined the effects of imbalanced branched-chain amino acid intake on growth outcomes in cblC-deficient patients.