Identification of a compound heterozygous mutation of ABCC2 in a patient with hyperbilirubinemia.

Bilirubin is the end product of heme catabolism, which is produced primarily from the breakdown of erythrocyte hemoglobin in the reticuloendothelial system. Hyperbilirubinemia is induced not only by increased bilirubin synthesis, but can also be caused by decreased bilirubin clearance. There are several disorders, which can contribute to hyperbilirubinemia, including Dubin‑Johnson syndrome (DJS). DJS is a rare autosomal recessive disorder, which is characterized by predominantly conjugated hyperbilirubinemia without progression to end‑stage liver disease. Previous studies have demonstrated that defects in multidrug resistance proteins ATP‑binding cassette C2 (ABCC2)/multidrug resistance‑associated protein 2 (MRP2) contribute to DJS. In the present study, a case of a patient with hyperbilirubinemia was examined and identified a compound heterozygous mutation in the ABCC2 gene (p.T435P and W442X). These were predicted to be deleterious by three bioinformatics programs (Polymorphism Phenotyping‑2, Sorting Intolerant From Tolerant and MutationTaster). These finding expand on the spectrum of ABCC2 mutations and provide additional evidence that ABCC2 is key in the development of DJS.