Fig. 4— A genome-wide search for quantitative trait loci (QTL) by selective genotyping of the 25 F2 cohort (50 meiosis), i.e. the most extreme high and low responders to intratracheal silica-instillation. a)–f): chromosomes 1–19; t): chromosome x. cM: centimorgans; ····:0; –––: suggestive linkage threshold; – – –: significant linkage threshold. Putative QTL on chromosomes 3, 4, 6, 10, 11, 14, and 18 identified by the genome scan were further analysed with the entire F2 cohort.