Iyengar SK, Elston RC, Goddard KA, Olson JM, Ialacci S, Fondran J, Horvath A, Igo R Jr, Jun G, Kramp K, Molineros J, Quade SR, Sedor JR, Schelling J, Pickens A, Humbert L, Getz-Fradley L, Adler S, Ipp E, Pahl M, Seldin MF, Snyder S, Tayek J, Hernandez E, LaPage J, Garcia C, Gonzalez J, Aguilar M, Klag M, Parekh R, Kao L, Meoni L, Whitehead T, Chester J, Knowler WC, Hanson RL, Nelson RG, Wolford J, Jones L, Juan R, Lovelace R, Luethe C, Phillips LM, Sewemaenewa J, Sili I, Waseta B, Saad MF, Nicholas SB, Chen YD, Guo X, Rotter J, Taylor K, Budgett M, Hariri F, Zager P, Shah V, Scavini M, Bobelu A, Abboud H, Arar N, Duggirala R, Kasinath BS, Thameem F, Stern M, Freedman BI, Bowden DW, Langefeld CD, Satko SC, Rich SS, Warren S, Viverette S, Brooks G, Young R, Spainhour M, Winkler C, Smith MW, Thompson M, Hanson R, Kessing B, Leehey DJ, Barone G, Thornley-Brown D, Jefferson C, Kohn OF, Brown CS, Briggs JP, Kimmel PL, Rasooly R, Warnock D, Cardon L, Chakraborty R, Dunston GM, Hostetter T, O'Brien SJ, Rioux J, Spielman R.
Source
Wake Forest School of Medicine, Winston-Salem, NC, USA.
Abstract
BACKGROUND:
African Americans have increased susceptibility to nondiabetic nephropathy relative to European Americans.
STUDY DESIGN:
Follow-up of a pooled genome-wide association study (GWAS) in African American dialysis patients with nondiabetic nephropathy; novel gene-gene interaction analyses.
SETTING & PARTICIPANTS:
Wake Forest sample: 962 African American nondiabetic nephropathy cases, 931 non-nephropathy controls. Replication sample: 668 Family Investigation of Nephropathy and Diabetes (FIND) African American nondiabetic nephropathy cases, 804 non-nephropathy controls.
PREDICTORS:
Individual genotyping of top 1,420 pooled GWAS-associated single-nucleotide polymorphisms (SNPs) and 54 SNPs in 6 nephropathy susceptibility genes.
OUTCOMES:
APOL1 genetic association and additional candidate susceptibility loci interacting with or independently from APOL1.
RESULTS:
The strongest GWAS associations included 2 noncoding APOL1 SNPs, rs2239785 (OR, 0.33; dominant; P = 5.9 × 10(-24)) and rs136148 (OR, 0.54; additive; P = 1.1 × 10(-7)) with replication in FIND (P = 5.0 × 10(-21) and 1.9 × 10(-05), respectively). rs2239785 remained associated significantly after controlling for the APOL1 G1 and G2 coding variants. Additional top hits included a CFH SNP (OR from meta-analysis in the 3,367 African American cases and controls, 0.81; additive; P = 6.8 × 10(-4)). The 1,420 SNPs were tested for interaction with APOL1 G1 and G2 variants. Several interactive SNPs were detected; the most significant was rs16854341 in the podocin gene (NPHS2; P = 0.0001).
LIMITATIONS:
Nonpooled GWASs have not been performed in African American patients with nondiabetic nephropathy.
CONCLUSIONS:
This follow-up of a pooled GWAS provides additional and independent evidence that APOL1 variants contribute to nondiabetic nephropathy in African Americans and identified additional associated and interactive nondiabetic nephropathy susceptibility genes.
Copyright © 2012 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.