Rat chromosome 9 bears a major susceptibility locus for IgE response

Injection of Brown Norway (BN) rats with gold salts provides a model to ana lyze the genetic control of the IgE response. A cohort of F2 progeny of sus ceptible BN and resistant LEW strains has been studied to carry out a genom e-wide search for loci controlling the IgE response. Genome scanning identi fied two previously described loci, Atps1 and Atps2, and a new locus, Atps3 . Atps1 linked to the MHC and Atps2 linked to the cytokine gene cluster tha t included the IL-4 region have been previously associated with serum IgE c oncentrations and with other Th2-dependent immune manifestations triggered by gold salts. The new interval, Atps3, identified on chromosome 9 (Lod sco re; 16), appears to play a major role in the control of the IgE response si nce it accounts for 31% of the genetic variance. Moreover, Atps3 is linked to anti-laminin antibody response and to glomerular immunoglobulin deposits . The identification and functional characterization of genes involved in t hese regions, particularly in Atps3, may shed light on the pathogenesis of atopic diseases in man.