Common treatment methods for MMA include a liver transplant or a liver and kidney transplant to combat the renal disease of methylmalonic acidemia. However, detrimental neurological effects can continue to plague patients even after a successful operation. It is thought that this is due to the widespread presence of methylmalonyl-CoA mutase throughout the central nervous system. Due to the loss of functionality of the enzyme, substrate levels build up in the CNS. The substrate, L-methylmalonyl-CoA hydrolyzes to form methylmalonate (methylmalonic acid), a neurotoxic dicarboxylic acid that, due to the poor dicarboxylic acid transport capacities of the blood-brain barrier, is effectively trapped within the CNS, leading to neurological debilitation. To combat these effects perioperative anti-catabolic regimes and no diet discontinuation are recommended.