Genetic Variations of the ABC Transporter Gene ABCB11 Encoding the Human Bile Salt Export Pump (BSEP) in a Japanese Population

The bile salt export pump (BSEP) encoded by ABCB11 is located in the canalicular membrane of hepatocytes and mediates the secretion of numerous conjugated bile salts into the bile canaliculus. In this study, 28 ABCB11 exons (including non-coding exon 1) and their flanking introns were comprehensively screened for genetic variations in 120 Japanese subjects. Fifty-nine genetic variations, including 19 novel ones, were found: 14 in the coding exons (6 nonsynonymous and 8 synonymous variations), 4 in the 3'-UTR, and 41 in the introns. Three novel nonsynonymous variations, 361C>A (Gln121Lys), 667C>T (Arg223Cys), and 1460G>T (Arg487Leu), were found as heterozygotes and at 0.004 allele frequencies. These data provide fundamental and useful information for genotyping ABCB11 in the Japanese and probably other Asian populations.