,117 Given the variable expressivity, which is relatively common among disorders of immune dysregulation, such as the CTLA-4 insufficiency and the STAT3 gain-of-function,13,14 on several occasions, segregation analysis has revealed typical rheumatic disease without significant evidence of immunodeficiency to segregate with a deleterious mutation in families, where the index patient came to attention and was subjected to genetic sequencing due to their immunodeficiency.118. This evidence concerns the gene STAT3 and immune system disorder.