In the present work, we have assessed anti-CR1 reactivity in brain as well as C1q and C3b binding to CR1 isolated from RBC of control or AD patients, with or without the GWAS-reported CR1 SNPs rs6656401and rs4844609, in order to determine if the diagnosis or SNPs would have an effect on CR1 distribution or function. The gene discussed is CR1; the disease is Alzheimer disease.