Absence of R1066X mutation in six Japanese patients with Dubin-Johnson syndrome

The Dubin-Johnson syndrome (DJS) is a rare autosomal recessive liver diseas e characterized by chronic conjugated hyperbilirubinemia. The phenotype of this syndrome is thought to be caused by the impaired expression or the can alicular multispecific organic anion transporter (cMOAT), which transports non-bile salt organic anions into the bile. Recently, a mutation from argin ine (Arg) to stop-codon at codon 1066 in the cMOAT gene has been reported i n one Caucasian patient with DJS. in this study, we investigated whether th is mutation is found in Japanese patients with DJS. Genomic DNAs were extra cted from the leukocytes of six Japanese patients and the fragments spannin g codon 1066 were amplified by polymerase-chain reaction, The digest of the amplified fragments with a restriction enzyme, TaqI, demonstrated that all of six patients did not exhibit an R1066X mutation. No mutation at Arg(106 6) was also confirmed by direct sequencing of the amplified products. These findings suggested that this R1066X mutation was not a major mutation in J apanese patients with DJS. Further investigation will be required in an att empt to search other mutations in cMOAT gene in Japanese patients with DJS.