title: Sequence analysis of bile salt export pump (ABCB11) and multidrug resistance p-glycoprotein 3 (ABCB4, MDR3) in patients with intrahepatic cholestasis of pregnancy.
abstract: Intrahepatic cholestasis of pregnancy (ICP) is a liver disorder associated with increased risk of intrauterine fetal death and prematurity. There is increasing evidence that genetically determined dysfunction in the canalicular ABC transporters bile salt export pump (BSEP, ABCB11) and multidrug resistance protein 3 (MDR3, ABCB4) might be risk factors for ICP development. This study aimed to (i). describe the extent of genetic variability in BSEP and MDR3 in ICP and (ii). identify new disease-causing mutations. Twenty-one women with ICP and 40 women with uneventful pregnancies were recruited between April 2001 and April 2003. Sequencing of BSEP and MDR3 spanned 8-10 kb per gene and comprised the promoter region and 100-350 bp of the flanking intronic region around each exon. DNA sequencing of polymerase chain reaction fragments was performed on an ABI3700 capillary sequencer. MDR3 promoter activity of promoter constructs carrying different ICP-specific mutations was studied using reporter assays. A total of 37 and 51 variant sites were detected in BSEP and MDR3, respectively. Three non-synonymous sites in codons for evolutionarily conserved amino acids were specific for the ICP collective (BSEP, N591S; MDR3, S320F and G762E). Furthermore, four ICP-specific splicing mutations were detected in MDR3 [intron 21, G(+1)A; intron 25, G(+5)C and C(-3)G; and intron 26, T(+2)A]. Activity of the mutated MDR3 promoter was similar to that observed for the wild-type promoter. Our data further support an involvement of MDR3 genetic variation in the pathogenesis of ICP, whereas analysis of BSEP sequence variation indicates that this gene is probably less important for the development of pregnancy-associated cholestasis.
authors.affiliation: Department of Internal Medicine, University Hospital Zürich, Zürich Switzerland.
authors.forename: Christiane
authors.initials: C
authors.lastname: Pauli-Magnus
authors.forename: Thomas
authors.initials: T
authors.lastname: Lang
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Meier
authors.forename: Tina
authors.initials: T
authors.lastname: Zodan-Marin
authors.forename: Diana
authors.initials: D
authors.lastname: Jung
authors.forename: Christian
authors.initials: C
authors.lastname: Breymann
authors.forename: Roland
authors.initials: R
authors.lastname: Zimmermann
authors.forename: Silke
authors.initials: S
authors.lastname: Kenngott
authors.forename: Ulrich
authors.initials: U
authors.lastname: Beuers
authors.forename: Christoph
authors.initials: C
authors.lastname: Reichel
authors.forename: Reinhold
authors.initials: R
authors.lastname: Kerb
authors.forename: Anja
authors.initials: A
authors.lastname: Penger
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Meier
authors.forename: Gerd A
authors.initials: GA
authors.lastname: Kullak-Ublick
mesh_terms: D018435:ATP Binding Cassette Transporter, Subfamily B / Q000235:genetics*; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters / Q000235:genetics*; D000595:Amino Acid Sequence; D006528:Carcinoma, Hepatocellular / Q000378:metabolism / Q000473:pathology; D002780:Cholestasis, Intrahepatic / Q000235:genetics*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D005260:Female; D005838:Genotype; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008113:Liver Neoplasms / Q000378:metabolism / Q000473:pathology; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011248:Pregnancy Complications; D011401:Promoter Regions, Genetic / Q000235:genetics; D020539:Sequence Analysis, Protein; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: C093491:ABCB11 protein, human; D018435:ATP Binding Cassette Transporter, Subfamily B; D000074020:ATP Binding Cassette Transporter, Subfamily B, Member 11; D018528:ATP-Binding Cassette Transporters; C095122:multidrug resistance protein 3