ARID1A and hairy cell leukemia: In addition, low-frequency mutations were identified on diverse epigenetic regulators including MLL3 (KMT2C, ~ 16%), ARID1A (~ 9%), CRERBBP (CBP, ~ 7%), KDM6A (~ 7%), and ARID1B (~ 4%), suggesting that epigenetic modifications may contribute to the pathogenesis of HCL.