Autosomal-dominant (AD) gain-of-function (GOF) variants in STAT1 result in chronic mucocutaneous candidiasis (CMC) (Hartono et al., 2018), while AD STAT1 deficiency that impairs type II IFN-induced STAT1-mediated signaling could lead to isolated MSMD (Casanova et al., 2024). Here, STAT1 is linked to Mendelian susceptibility to mycobacterial diseases.