Pathogenic variants of <i>CYBB</i> [cytochrome b(-245), beta subunit; Mendelian Inheritance in Man [MIM] accession code, 300481] are known to cause "immunodeficiency 34, mycobacteriosis, X-linked" (IMD34, MIM#300645) and "chronic granulomatous disease, X-linked" (CGDX, MIM#306400). Here, CYBB is linked to immunodeficiency disease.