In the context of SLE susceptibility, one of the most consistently mapped non-MHC regions of the mouse genome is the telomeric Chromosome 1 segment, where several disease loci, designated Sle1 (Morel et al. 2001), Nba2 (Drake et al. 1995; Rozzo et al. 1996; Vyse et al. 1997), and Bxs3 (Hogarth et al. 1998), have been mapped in lupus-prone strains. The gene discussed is HLA-C; the disease is systemic lupus erythematosus.