Living donor–domino liver transplantation for maple syrup urine disease: surgical and metabolic outcomes

This study evaluates the feasibility and safety of combining living donor liver transplantation (LDLT) with domino liver transplantation (DLT) for maple syrup urine disease (MSUD). MSUD causes neurological impairment due to branched-chain amino acid accumulation (BCAA). Liver transplantation restores metabolic homeostasis via branched-chain ketoacid dehydrogenase (BCKDH) present in the donor graft. MSUD livers can be reused as domino liver grafts (DLG) since enzyme deficiency in DLG is supplied by production in other recipient’s tissues. From October 2012 to September 2025 live donors (LD), MSUD patients and DLG recipients were enrolled for DLT and followed for at least 1 year after transplantation. Plasma BCAA levels in MSUD patients at 3 time points (pretransplantation, early [1–90 d], and late [>90–365 d] posttransplantation) were compared with age-matched pediatric controls without metabolic disorders. Surgical and metabolic outcomes were monitored up to 1-year post-transplantation. Among 32 LDLT for MSUD, 27 (84.4%) grafts were reused. Patient/graft survival was 93.8% for MSUD recipients and 96.3%/85.2% for DLG recipients, respectively. Late hepatic artery thrombosis occurred in 3.1% of MSUD patients and 7.4% of DLG recipients. Primary factors for DLG disposal were double arteries and younger MSUD patients, related to small arterial caliber. No increased risk related to DLG donation was demonstrated. Combining LDLT and DLT expands the donor pool for pediatric patients while ensuring safety in MSUD treatment, with microsurgical arterial reconstruction supporting DLG reuse. Higher graft-to-recipient weight ratio (GRWR) was associated with better early metabolic control, but this association was not significant after adjustment for age, suggesting that the apparent contribution of graft size to early metabolic adaptation may be age-related.