A variable degree of immunodeficiency has been primarily linked to the variants affecting the switch II domain in the CDC42 gene (Takenouchi et al., 2015; Takenouchi et al., 2016; Martinelli et al., 2018; Motokawa et al., 2018; Uehara et al., 2019; Bucciol et al., 2020; Asiri et al., 2021; Ishikawa et al., 2021; Kashani et al., 2021; Santoro et al., 2021). This evidence concerns the gene CDC42 and immunodeficiency disease.