AFF1 and acute lymphoblastic leukemia: In addition, several infant or pediatric malignancies appear to be due to a single genetic event: MLL-AF4 fusion in infant acute lymphoblastic leukemia [42], homozygous inactivation of SMARCB1 in pediatric rhabdoid tumors [43], and C11orf95-RELA fusion in brain ependymoma [44].