Mariano et al. examined plasma homocysteine levels, serum folate and vitamin B12 concentrations, plasma pyridoxal phosphate levels, C-reactive protein, and antibodies of immunoglobulin G (IgG) and immunoglobulin A (IgA) against Helicobacter pylori (HP) in 30 AD patients and found an association between HP infection and AD (Malaguarnera et al., 2004). The gene discussed is CD79A; the disease is Alzheimer disease.