This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
What is the defect in Dubin Johnson syndrome 
Select and explain. 
A. Mutation in ATP7B gene, B. Mutation in MRP - 2 gene, C. Mutation in UGT1A1 gene, D. Mutation in ATP7A gebe
B: Mutation in MRP - 2 gene
Answer: B: Mutation in MRP - 2 gene 
Explanation: In Dubin Johnson syndrome these is impaired biliary excretion of bilirubin glucuronides due to mutation in canalicular multidrug Resistance Protein -2 (MRP- 2).