Association of ABCB1 genetic variants with renal function in Africans and in Caucasians
1 University Institute of Social and Preventive Medicine (IUMSP), Centre Hospitalier Universitaire Vaudois and University of Lausanne, Bugnon 17, Lausanne, Switzerland
2 Unit of Biochemistry and Clinical Psychopharmacology, Center for Psychiatric Neurosciences, Department of Psychiatry, Centre Hospitalier Universitaire Vaudois and University of Lausanne Lausanne, Switzerland
3 Division of Nephrology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
4 Department of Medical Genetics, University of Lausanne, Lausanne, Switzerland
5 Swiss Institute of Bioinformatics, Lausanne, Switzerland
6 Department of Medicine, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
7 Ministry of Health, Victoria, Seychelles
8 Department of Epidemiology and Biostatistics, Case Western Reserve University, Cleveland (OH), USA
9 Service of Medical Genetics, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland
10 Division of Genetics, GlaxoSmithKline, Philadelphia, Pennsylvania, USA
BMC Medical Genomics 2008, 1:21 doi:10.1186/1755-8794-1-21Published: 2 June 2008
The P-glycoprotein, encoded by the ABCB1 gene, is expressed in human endothelial and mesangial cells, which contribute to control renal plasma flow and glomerular filtration rate. We investigated the association of ABCB1 variants with renal function in African and Caucasian subjects.
In Africans (290 subjects from 62 pedigrees), we genotyped the 2677G>T and 3435 C>T ABCB1 polymorphisms. Glomerular filtration rate (GFR) was measured using inulin clearance and effective renal plasma flow (ERPF) using para-aminohippurate clearance. In Caucasians (5382 unrelated subjects), we analyzed 30 SNPs located within and around ABCB1, using data from the Affymetrix 500 K chip. GFR was estimated using the simplified Modification of the Diet in Renal Disease (MDRD) and Cockcroft-Gault equations.
In Africans, compared to the reference genotype (GG or CC), each copy of the 2677T and 3435T allele was associated, respectively, with: GFR higher by 10.6 ± 2.9 (P < 0.001) and 4.4 ± 2.3 (P = 0.06) mL/min; ERPF higher by 47.5 ± 11.6 (P < 0.001) and 28.1 ± 10.5 (P = 0.007) mL/min; and renal resistances lower by 0.016 ± 0.004 (P < 0.001) and 0.011 ± 0.004 (P = 0.004) mm Hg/mL/min. In Caucasians, we identified 3 polymorphisms in the ABCB1 gene that were strongly associated with all estimates of GFR (smallest P value = 0.0006, overall P = 0.014 after multiple testing correction).
Variants of the ABCB1 gene were associated with renal function in both Africans and Caucasians and may therefore confer susceptibility to nephropathy in humans. If confirmed in other studies, these results point toward a new candidate gene for nephropathy in humans.