Polymorphism of the human MDR1 gene in Siberian and Central Asian populations

The multidrug resistance gene MDR1 (ABCB1) codes for a P-glycoprotein that acts as an ATP-dependent transporter and is involved in removing drugs, xenobiotics, and peptides from the cell. MDR1 is expressed in the brain, kidneys, liver, and gastrointestinal tract. The P-glycoprotein is thought to play a role in individual resistance to xenobiotics and infections. Several polymorphisms of MDR1 are associated with the level of its expression and resistance to various neurodegenerative and gastrointestinal diseases. The allele and haplotype frequencies, genetic differentiation, and linkage disequilibrium for five MDR1 single nucleotide polymorphisms (3435C/T, 2677G/T/A, 1236C/T, +139C/T, and -1G/A) were studied in the Russian, Tuvinian, and northern and southern Kyrgyz populations. Significant genetic differences were observed between Russians and northern Kyrgyz and between Tuvinians and northern Kyrgyz. The linkage disequilibrium pattern was characterized by high population specificity.