ADA and severe combined immunodeficiency: A few iPSC models of gene therapy for primary immunodeficiencies – genetic disorders of impaired immunity against pathogens – have been generated, including for severe combined immunodeficiency (SCID; X-linked, RAG1-SCID and ADA-SCID), chronic granulomatous disease (CGD) and Wiscott-Aldrich syndrome (WAS) (Brauer et al., 2016; Chang et al., 2015; Dreyer et al., 2015; Flynn et al., 2015; Ingrungruanglert et al., 2015; Jiang et al., 2012; Laskowski et al., 2016; Laugsch et al., 2016; Menon et al., 2015; Merling et al., 2015; Park et al., 2008a; Sweeney et al., 2017; Zou et al., 2011b).