Fine mapping of trypanosomosis resistance Loci in murine by haplotype approach
Mapping of trypanotolerance QTL in two F2 resource populations generated by crossing BALB/c and A/J with C57BLl6J has previously been achieved by Kemp et al., (1997). The subsequent fine mapping using the advanced intercross line (AIL) found the same to be true in F6 using same strains of mice (Iraqi et al., 2000). To confirm and fine map the QTL, a genome-wide scan for quantitative trait loci (QTLs) affecting trypanotolerance in a population of 300 F2 progeny derived from a cross between 129/J and, C57BLl6J. Two trypanotolerance QTLs (Tirl and Tir3) were detected at the genome-wide 5% or less level. Tirl and Tir3, located on Chromosomes (Chrs) 17and 1, respectively, had main effects on trypanotolerance. However, Tir2 on Chr 5 was not detected at the same level and had LOD score bellow 2. Resistant (tolerant) alleles derived from C57BLl6J were responsible for the high trypanotolerance effect. These results indicated that the genetic control of trypanotolerance is complex and the identified QTLs may provide new insights into the pathogenesis of trypanotolerance in mice as well as in livestock and humans.