Stabilization of blood methylmalonic acid level in methylmalonic acidemia after liver transplantation

Methylmalonic acidemia with complete mutase deficiency (mut0 type) is an inborn error of metabolism with high mortality and morbidity. LT has been suggested to be a solution to this disease, but elevation of urinary and blood MMA was still observed after LT. In this study, we measured dry blood spot MMA and its precursor propionyl-carnitine (C3-carnitine) for mut0 patients. The results revealed that when C3-carnitine rose during metabolic stress, MMA rose exponentially (up to 1000 μmol/L) in patients who did not undergo LT. In patients who underwent LT, MMA rose to 100-200 μmol/L when C3-carnitine reached 10-20 μmol/L. However, when C3-carnitine rose further to 40-50 μmol/L, MMA levels just stayed put. Therefore, LT stabilized blood MMA level, though there might be a threshold for blood MMA clearance by the donor liver. This finding should be critical to understand the long-term outcome for LT in methylmalonic acidemia. ? 2009 John Wiley & Sons A/S.