Linkage mapping of the rat interleukin 1 receptor antagonist gene on chromosome 3.

activity of these two cytokines is neutralized. Specific alleles of the human IL1RN were found to be associated with chronic hypochlorhydric response to Helicobacter pylori infection and the risk of gastric cancer [4], and with severe clinical symptoms in several chronic inflammatory diseases, including systemic lupus erythematosus [5], ulcerative colitis [6] and alopecia areata [7]. Two SNPs were identified in the intron 1 of the Il1rn gene between the ACI and WTC strains (accession numbers AB045625 and AB045626). Another SNP was also detected in the intron 3 (accession number AB045627). These three SNPs were genotyped by SSCP analysis among 8 rat inbred strains (Fig. 1, Table 1). Rat Il1rn gene was mapped to the proximal portion of rat Chr 3 using the SNP marker D3Ncc46 (Fig. 2). The chromosomal synteny established in this study, human Chr 2q14.2, mouse Chr 2 (10) and rat Chr 3, has not been reported [8]. The chromosomal position of D3Ncc46/Il1rn allows us to determine the precise proximal border of the syntenic region between rat Chr 3 and mouse Chr 2. The entire rat Chr 3 might correspond to the extended region of mouse Chr 2 (from 10-cM to telomere), while a part of rat Chr 17 might correspond to the remaining small part of mouse Chr 2 near the centromere (from 0to 9-cM).