Abbreviations CA = chronic arthritis; CIA = collagen-induced arthritis; CV = coefficiant of variation; GO = Gene Ontology; LN = lymph node; LOD = logarithm of the odds; MAPK = mitogen-activated protein kinase; NC = naive control; OA = onset of arthritis; PI = post-immunisation; QTG = quantitative trait gene; QTL = quantitative trait loci; RA = rheumatoid arthritis.