ANKRD55 (ankyrin repeat domain 55) is a nuclear protein predominantly expressed in CD4+ T cells that functions as a critical regulator of T cell-mediated inflammation and immune responses 1. The protein contains ankyrin repeat domains that facilitate protein-protein interactions 2, and genetic variants in ANKRD55 are associated with multiple sclerosis (MS), rheumatoid arthritis, and type 2 diabetes risk 34. Mechanistically, ANKRD55 regulates T cell receptor (TCR) signaling by interacting with subunits of the chaperonin-containing TCP1 (CCT) complex to modulate immune synapse formation and proper microtubule organization 1. ANKRD55 deficiency impairs Th1 and Th17 differentiation in experimental autoimmune encephalomyelitis, reducing disease severity and neuroinflammation 1. The protein also localizes to nuclear speckles and participates in mitotic spindle dynamics through interactions with cohesin complexes and tubulin 2. MS-associated risk alleles correlate with elevated ANKRD55 expression in CD4+ T cells and dendritic cells 56, while ANKRD55 variants associate with decreased insulin sensitivity in type 2 diabetes 7. ANKRD55 represents a therapeutic target for pathogenic T cell-driven autoimmune diseases.