As B cell-mediated atheroprotection in mice depends on Id3, the association of the functional polymorphism in ID3 with measures of atherosclerosis [11] in humans raises the intriguing hypothesis that ID3 may mediate B cell atheroprotection in humans and the polymorphism at rs11574 may identify those with loss of this humoral immune protection. The gene discussed is ID3; the disease is atherosclerosis.