Table 1.

Biological features in adolescents and young adults (AYA) with acute lymphoblastic leukemia (ALL)

Characteristic	Comment
Cytogenetics	Low incidence of: hyperdiploidy, t(12;21) High incidence of: hypodiploidy, t(9;22), other poor risk cytogenetics, IgH@ translocations, complex karyotype
Molecular genetics	Increased frequency of mutations of: CRLF2, JAK, IKZF1, CDNK2A/B High incidence of: IAMP21, BCR-ABL-like
Immunophenotype	Higher incidence of early T precursor ALL
Response to chemotherapy	Higher MRD burden after induction chemotherapy
Tolerabilty to intensive chemotherapy	Poorer in some studies