PRC1 and acute lymphoblastic leukemia: While genetic alterations in PRC1 factors are rare, reduced function of PRC2 due to mutation or deletion is common in acute myeloid leukaemia (AML) and the immature subgroup of T-acute lymphoblastic leukaemia (T-ALL), as well as the rarer T/myeloid mixed phenotype acute leukaemia (MPAL) subtype.