SLC22A2 is associated with tubular creatinine secretion and bias of estimated GFR in renal transplantation

Reznichenko A, Sinkeler SJ, Snieder H, van den Born J, de Borst MH, Damman J, van Dijk MC, van Goor H, Hepkema BG, Hillebrands JL, Leuvenink HG, Niesing J, Bakker SJ, Seelen M, Navis G. SLC22A2 is associated with tubular creatinine secretion and bias of estimated GFR in renal transplantation. Physiol Genomics 45: 201-209, 2013. First published January 22, 2013; doi:10.1152/physiolgenomics.00087.2012.-Genomewide association studies reported SLC22A2 variants to be associated with serum creatinine. As SLC22A2 encodes the organic cation transporter 2 (OCT2), the association might be due to an effect on tubular creatinine handling. To test this hypothesis we studied the association of SLC22A2 polymorphisms with phenotypes of net tubular creatinine secretion: fractional creatinine excretion (FEcreat) and bias of estimated glomerular filtration rate (eGFR). We also studied the association with end-stage renal disease (ESRD) and graft failure (GF) in renal transplant recipients. SLC22A2 single nucleotide polymorphisms (SNPs), rs3127573 and rs316009, were genotyped in 1,142 ESRD patients receiving renal transplantation and 1,186 kidney donors as controls. GFR was measured with I-125-iothalamate clearance. Creatinine clearance was also assessed. FEcreat was calculated from the simultaneous clearances of creatinine and I-125-iothalamate. Donor rs316009 was associated with FEcreat (beta -0.053, P = 0.024) and with estimated [modification of diet in renal disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)] but not measured GFR. In line with this, donor rs316009 was associated with bias of the MDRD and CKD-EPI but not the Cockroft-Gault equation. Both SNPs were associated with ESRD: odds ratios [95% CI] 1.39 [1.16-1.67], P = 0.00065, and 1.23 [1.02-1.48], P = 0.042, for rs3127573 and rs316009, respectively. Neither SNP was associated with GF. Thus, SLC22A2 is associated with phenotypes of net tubular creatinine secretion and ESRD.