For example, heterozygous mutations in the stat3 gene leading to replacements of key amino acids, such as K392R, M394T and K658N, and enhanced STAT3 binding, or dimerization are associated with multi-organ autoimmunity, lymphoproliferation and hypogammaglobulinemia with terminal B cell maturational arrest [300]. Here, STAT3 is linked to Autoimmunity.