The three GWAS breeds (high risk of OS) and the AKC greyhounds (low risk of OS) are genetically distinct and highly inbred populations. (a) Along the top two principal components of variation, the three breeds (Rottweilers (n = 135, red), Irish wolfhounds (IWH, n = 141, purple), and racing greyhounds (n = 267, dark blue) ) are each tight clusters equidistant apart, with the AKC subpopulation of greyhounds (n = 19, light blue) near but not overlapping the racing dogs. (b) Estimate of the inbreeding coefficient (IC) shows the racing greyhounds as the least inbred, on average, while the other three populations fall within the range seen in an earlier survey of 28 dog breeds (grey bars mark average IC in breed; two outliers at 0.53 and 0.62 not shown) . (c) The extent of linkage disequilibrium, measured as average pair-wise r2, drops below 0.2 at 196 kb, 632 kb, and 1,533 kb in the greyhounds, Rottweilers, and IWH, respectively.
Karlsson et al. Genome Biology 2013 14:R132 doi:10.1186/gb-2013-14-12-r132