Since CD33 does not have a clear mouse ortholog (Mancuso et al., 2019), proposed transplantation studies using fluorescent human iPSC-derived microglia with altered CD33, either derived from patients or genetically engineered, could provide an opportunity to learn more about AD-associated functions of CD33, especially about its protective variant (Hollingworth et al., 2011; Naj et al., 2011; Griciuc et al., 2013). The gene discussed is CD33; the disease is Alzheimer disease.