Figure 2. Pedigree of the six Basenji dogs affected with progressive retinal atrophy (PRA) selected as cases for the genome-wide association study. Square symbols=males; Circles=females. Solid black symbols=affected dogs; Grey symbols=dogs of unknown phenotype; half-black/half-gray symbols=dogs that, assuming autosomal recessive inheritance, are at least obligate heterozygotes. The male dog marked with an asterisk is common to the maternal and paternal ancestral lines of all six affected dogs in this pedigree. Not all ancestors or lines of descent are shown.