RB1 and acute lymphoblastic leukemia: Among the 227 ALL patients consecutively treated in our department, during the years 2000–2020 (median follow-up time 113.9 months), 85 patients were checked by MLPA (Salsa-MLPA-P335-Kit), for the evaluation of the copy number status of 8 genes: IKZF1, CDKN2A/2B, PAR1, BTG1, EBF1, PAX5, ETV6, RB1.