The IL2 and IL21 genes located next to each other on human chromosome 4 (107), and IL4RA and IL21RA on chromosome 16 (108) also bear a strong association with autoimmunity, potentially reflecting the key roles of IL-21 and IL-4 in orchestrating collaboration between Tfh and B cells within GC (109, 110). Here, IL21 is linked to Autoimmunity.