Abstract
Methylmalonic acidemia (MMA) is caused by a deficiency of methyl-malonyl-CoA mutase. It is a multisystemic condition with poor clinical outcomes characterized by frequent metabolic decompensation with acidosis, hyperammonemia and encephalopathy. Restriction of intact protein and supplementation with amino acid-based formula play an important role in its management. Recently, liver transplant (LT) became a treatment option for MMA patients. However, there has been no current consensus on the post-operative nutrition management for MMA patients undergoing transplant, particularly during the initial phase of recovery period with catabolic stressors. We performed a retrospective analysis of clinical and nutritional management as well as biochemical profiles before and after LT in five patients with MMA. Through this study, we observed significant improvement of MMA-associated metabolites after LT. MMA patients were able to tolerate increased intact protein intake post-operatively. At least 1–1.5 g/kg/day of total protein during the acute phase after transplant may be tolerated without worsening of the metabolite levels. This information provides a guide in how to nutritionally manage MMA after LT.
Highlights
Methylmalonic acidemia (MMA) (OMIM: 251000) is an organic acidemia caused by pathogenic variants in the MMUT gene encoding the enzyme, methyl-malonyl-CoA mutase, which is important for the metabolism of valine, methionine, isoleucine, threonine and odd-chain fatty acids [1]
The enzymatic defect causes accumulations of methylmalonic acid in the body, resulting in multisystemic disease. It can present as lethargy, vomiting, metabolic acidosis, hyperammonemia and encephalopathy during the newborn period and can result in coma or death if untreated [2]
Because of the enzymatic defect, MMA patients are very sensitive to protein loads and an excessive amount of protein intake or increased catabolism can trigger a higher accumulation of methylmalonic acid leading to metabolic acidosis [3]
Summary
Methylmalonic acidemia (MMA) (OMIM: 251000) is an organic acidemia caused by pathogenic variants in the MMUT gene encoding the enzyme, methyl-malonyl-CoA mutase, which is important for the metabolism of valine, methionine, isoleucine, threonine and odd-chain fatty acids [1]. The enzymatic defect causes accumulations of methylmalonic acid in the body, resulting in multisystemic disease. It can present as lethargy, vomiting, metabolic acidosis, hyperammonemia and encephalopathy during the newborn period and can result in coma or death if untreated [2]. Dietary protein restriction with precursor-free amino acid (PFAA) formulas, which are methionine- and valine-free with low isoleucine and threonine, and carnitine supplementation play an important role in its medical management
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