The alteration in BCR signaling by low levels of exposure to mercury for the pathogenesis of autoimmune disease is discussed by R. F. Gill et al. Their report showed that Hg2+ has little upstream effects on BHC tyrosine kinase, but SYK tyrosine kinase and B cell scaffolding protein BLNK are augmented by low levels of mercury, suggesting that low levels of mercury may interfere with central tolerance and may be a mechanism connecting mercury intoxication to autoimmune disease. The gene discussed is BLNK; the disease is autoimmune disease.