AFF1 and leukemia: Most these MLL fusions are unable to generate fusion proteins because of recombination between noncompatible introns or head-to-head fusions.[4]AFF1, MLLT3, MLLT1, MLLT11, and ELL, which are most frequent involvement with 3-way translocations, are considered the most common partners identified in leukemia with MLL rearrangement.[11] Also, it has been reported that 17% of cases display complex rearrangements between chromosomes 4, 11, and a third chromosome in all MLL-AFF1 fusion-positive cases.[5]