Anti-Gal IgM, IgG, and IgA activities were found to be elevated in patients of Crohn’s disease (D’Alessandro et al., 2002), whereas only anti-Gal IgA is elevated in Henoch–Schönlein purpura (Davin et al., 1987), in ulcerative colitis (D’Alessandro et al., 2002), and in Alzheimer’s disease (Angiolillo et al., 2021). The gene discussed is CD79A; the disease is early-onset autosomal dominant Alzheimer disease.