While the common phenotypic denominator is chronic mucocutaneous candidiasis [CMC—in 98% of the patients (4)], less frequent phenotypes were also associated with STAT1 GOF, like John Cunningham (JC)-virus induced progressive multifocal leukoencephalopathy (5), immunodysregulation polyendocrinopathy enteropathy X-linked (IPEX)-like syndromes with CMC (6, 7), Orf infection (8), and combined immunodeficiency (CID) without CMC (9). Here, STAT1 is linked to combined immunodeficiency.