Linkage of chromosome 1, 7, and 17 markers with Coombs antibody activities in B6 × (NZB × B6.Yaa)F1 BC male mice bearing the Yaa mutation. Coombs antibody activities were determined at 6 and 10 months of age. LOD scores were generated with MAPMAKER/QTL, and the highest scores obtained at 10 months of age are shown. The horizontal dotted line represents the threshold for suggestive linkage.