A meta-analysis of 2901 individuals (1311 AD patients and 1590 healthy control subjects) revealed a significant increase in the amount of endogenous IgG autoantibodies targeting Aβ in the blood; by contrast, anti-Aβ IgM autoantibody levels were markedly lower in patients with AD than in control subjects, suggesting the possibility that alterations in autoantibody levels may be a biomarker [89]. The gene discussed is CD40LG; the disease is Alzheimer disease.