Genetic complexity of association with urate at SLC2A9. The left panel, taken from Wei and colleagues , illustrates the epistatic SNP-SNP interactions that are present at the SLC2A9 locus and that concentrate on the indicated 30 kb region. The right panel, taken from Köttgen and colleagues , demonstrates the extent of extremely strong association at the SLC2A9 locus. The approximate positions of the urate-associated copy number variants identified by Scharpf and colleagues  are arrowed. The genomic co-ordinates differ between each study because Wei and colleagues  used Human Genome Project NCBI build 37.3 and Scharpf and colleagues  used NCBI build 36. NCBI, National Center for Biotechnology Information; SNP, single-nucleotide polymorphism.