Multidrug resistance protein-2 encoded by the ABCC2 gene (MRP2/ABCC2), an efflux transporter expressed at the proximal renal tubule, is rate-limiting for urine excretion of coproporphyrin (UCP) isomers I and III, translating in high UCP [I/(I + III)] ratio in MRP2-deficient patients presenting with the Dubin-Johnson Syndrome.
The molecular basis in Dubin-Johnson syndrome is absence or deficiency of human canalicular multispecific organic anion transporter MRP2/cMOAT caused by homozygous or compound heterozygous mutation(s) in ABCC2 located on chromosome 10q24.
The mutations in MRP2/ABCC2 leading to conjugated hyperbilirubinemia (Dubin-Johnson syndrome) and in MRP6/ABCC6 leading to the connective tissue disorder Pseudoxanthoma elasticum are also discussed.
FVII deficiency in both populations is caused by a founder A244V mutation in the F7 gene and DJS is caused by two founder mutations, I1173F and R1150H in the MRP2 gene that are specific for Iranian and Moroccan Jewish patients, respectively.
We hypothesized that RS can be an allelic variant of Dubin-Johnson syndrome, caused by mutation in ABCC2, and investigated ABCC2 (gene) and ABCC2 (protein) in two patients with RS.
A comprehensive list of sequence variants in the human ABCC2 gene summarizes predicted and proven functional consequences, including variants leading to Dubin-Johnson syndrome.
This study suggests that long-term follow-up is indicated for neonatal DJS because of possible recurrence and/or second attacks of jaundice in later life, and that disruption of functionally important ABC domains in MRP2 may be related to the earlier onset of the disease.
In the present study, we report the effects of chronic administration of both drugs in a patient with Dubin-Johnson syndrome (DJS), an inherited autosomal recessive disorder characterized by the absence of functional MRP2 protein at the canalicular hepatocyte membrane.
Several naturally occurring mutations leading to the absence of functional MRP2 protein from the apical membrane have been described causing the human Dubin-Johnson syndrome associated with conjugated hyperbilirubinaemia.
We postulated that loss-of-function mutations in ABCC2, which are involved in the Dubin-Johnson syndrome, may be associated with impaired methotrexate elimination and an increased risk of toxicity.
To clarify the genetic basis of the disease and the long-term stability of serum bilirubin levels, we conducted a mutational analysis of the MRP2 gene and followed up serum bilirubin levels in Japanese DJS patients 30 years after they were originally diagnosed, based on traditional criteria.
In this work, we analyzed a relatively frequent Dubin-Johnson syndrome mutation that leads to an exchange of two hydrophobic amino acids, isoleucine 1173 to phenylalanine (MRP2I1173F), in a predicted extracellular loop of MRP2.
We investigated the consequences of 2 missense mutations, R768W and Q1382R, of nucleotide-binding domains (NBDs) of the multidrug resistance protein 2 (MRP2; ABCC2) that were previously identified in patients with DJS.
The aim of this study was to identify the mutations in two previously characterized clusters of patients with Dubin-Johnson syndrome among Iranian and Moroccan Jews and determine the consequence of the mutations on MRP2 expression and function by expression studies.
Several mutations in the human MRP2 gene have been identified that lead to the absence of MRP2 from the canalicular membrane and to the conjugated hyperbilirubinemia of Dubin-Johnson syndrome.
This is the first mutation in Dubin-Johnson syndrome shown to cause deficient MRP2 maturation and impaired sorting of this glycoprotein to the apical membrane.