FAS and autoimmune lymphoproliferative syndrome: Other IEIs with somatic mosaicism as a reported etiology include but are not limited to FAS-related autoimmune lymphoproliferative syndrome (Dowdell et al., 2010); TLR8-related immunodeficiency with bone marrow failure (Aluri et al., 2021); and UBA1-related severe and often fatal, adult-onset autoinflammatory disease (Beck et al., 2020).