Sequence analysis of bile salt export pump (ABCB11) and multidrug resistance p-glycoprotein 3 (ABCB4, MDR3) in patients with intrahepatic cholestasis of pregnancy

Autor: Pauli-Magnus, Christiane, Lang, Thomas, Meier, Yvonne, Zodan-Marin, Tina, Jung, Diana, Breymann, Christian, Zimmermann, Roland, Kenngott, Silke, Beuers, Ulrich, Reichel, Christoph, Kerb, Reinhold, Penger, Anja, Meier, Peter J, Kullak-Ublick, Gerd A
Zdroj: Pharmacogenetics; February 2004, Vol. 14 Issue: 2 p91-102, 12p
Abstrakt: 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 BSEPand MDR3in 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 BSEPand MDR3spanned 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. MDR3promoter 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 BSEPand 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 MDR3promoter was similar to that observed for the wild-type promoter. Our data further support an involvement of MDR3genetic variation in the pathogenesis of ICP, whereas analysis of BSEPsequence variation indicates that this gene is probably less important for the development of pregnancy-associated cholestasis.
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