Location of polymorphic DNA markers used for the (A/J × CASA/RkJ) F2 genome scan. Black circles represent unlinked markers, open circles represent failed or indeterminate markers, and gray circles designate markers with suggestive linkage by visual assessment of pooled samples. After examining individual genotypes within the pools, only D6Mit12 achieved statistically significant linkage (asterisk). This linkage was subsequently confirmed after extended genotype analysis of the entire F2 population (n = 200).