Maple syrup urine disease (MSUD) is an autosomal recessive disease associated with
high levels of branched-chain amino acids. Children with MSUD can present severe
neurological damage, but liver transplantation (LT) allows the patient to resume a
normal diet and avoid further neurological damage. The use of living related donors
has been controversial because parents are obligatory heterozygotes. We report a case
of a 2-year-old child with MSUD who underwent a living donor LT. The donor was the
patient's mother, and his liver was then used as a domino graft. The postoperative
course was uneventful in all three subjects. DNA analysis performed after the
transplantation (sequencing of the coding regions of BCKDHA,
BCKDHB, and DBT genes) showed that the MSUD
patient was heterozygous for a pathogenic mutation in the BCKDHB
gene. This mutation was not found in his mother, who is an obligatory carrier for
MSUD according to the family history and, as expected, presented both normal clinical
phenotype and levels of branched-chain amino acids. In conclusion, our data suggest
that the use of a related donor in LT for MSUD was effective, and the liver of the
MSUD patient was successfully used in domino transplantation. Routine donor
genotyping may not be feasible, because the test is not widely available, and, most
importantly, the disease is associated with both the presence of allelic and locus
heterogeneity. Further studies with this population of patients are required to
expand the use of related donors in MSUD.