Binds KMT2A/MLL1. Component of the MLL1/MLL complex, at least composed of KMT2A/MLL1, ASH2L, RBBP5, DPY30, WDR5, MEN1, HCFC1 and HCFC2 (By similarity). Interacts with TASOR (PubMed:31112734). Expressed in the spermatogonia, spermatocytes and ovary. Truncated N-terminus.