Objective  To evaluate the clinical efficacy of heterozygous living donor liver transplantation for pediatric maple syrup urine disease.

  Methods  A 3-year-old boy was admitted to the hospital on July 5, 2017 due to maple syrup urine disease for half a year. The child presented with paroxysmal dysarthria and motor dysfunction of the lower limbs under fasting status for half a year, accompanied with obvious maple syrup urine odor and slow language development. No other growth abnormality or mental defects were observed. Serum branched chain amino acid (BCAA) assay detected that the level of leucine was 684 μmol/L and 559 μmol/L for the valine. The child was diagnosed with maple syrup urine disease type b based on gene detection combined with BCAA assay. Living donor liver transplantation from his biological father was performed. Postoperatively, routine immunosuppression, anti-virus, anti-infection therapies, maintenance of fluid, electrolyte, and acid-base balance and other necessary nutritional support were given. The dose of tacrolimus was adjusted according to biochemical parameters and cytochrome P450(CYP)3A5 genotype of the recipient. Glucocorticoid administration was terminated at approximately 6 months after operation.

  Results  The liver function of the recipient was recovered to normal range at postoperative 1 month, and basically stabilized at 3 years after surgery. The amino acid level was decreased to normal level immediately after operation, and BCAA was continually declined after normal diet for postoperative 1 month. As of the submission date, the recipient grew well in a stable condition and achieved high quality of life.

  Conclusions  Heterozygous living donor liver transplantation is a safe and effective treatment of maple syrup urine disease, which reduces the possibility of sudden acute metabolic events, significantly improves the quality of life of the recipient and provides a novel idea for surgical treatment of maple syrup urine disease.