Liver transplantation in maple syrup urine disease

Maple syrup urine disease (MSUD) is an autosomal recessive disorder. Impaired activity of the branched-chain 2-oxoacid dehydrogenase complex (BCOA-DH) causes accumulation of branched-chain L-amino (BCAA) and 2-oxoacids (BCOA) which may exert neurotoxic effects. Treatment comprises dietary management with strictly reduced quantities of protein and BCAA as well as aggressive intervention during acute neonatal and subsequent metabolic complications. MSUD is regarded as a metabolic disorder with potentially favourable outcome when the patients are kept on a carefully supervised long-term therapy. Up to now, three MSUD patients, exhibiting the classical form of the disease, have received orthotopic whole liver transplantation (OLT). Liver replacement resulted in a clear increase in whole body BCOA-DH activity to at least the level of very mild MSUD variants. These patients no longer require protein restricted diets and the risk of metabolic decompensation during catabolic events is apparently abolished.

Considering the overall expenses, risks, and outcome, however, the benefit of OLT, even in the most severe form of MSUD, may not be significantly different from that of a classical strict dietary management. Thus, OLT appears not to represent a specific option in the treatment in MSUD.