STAT1 and inborn error of immunity: Inborn errors of human STAT1 with loss-of-function (LOF) mutations cause three types of primary immunodeficiencies: (1) autosomal recessive (AR), characterized by biallelic complete LOF mutations of STAT1 and complete STAT1 deficiency, (2) AR partial STAT1 deficiency caused by biallelic hypomorphic STAT1 mutations, and (3) autosomal dominant (AD) heterozygous STAT1 deficiency.