T-ALL most common genetic alterations such as STIL-TAL1 rearrangement, TLX3 rearrangement, NOTCH1 and FBXW7 mutations were assessed, to evaluate CD44 expression levels in different molecular subgroups; 22 cases (21.0%) were STIL-TAL1 positive and 5.3% TLX3; 50 cases (48.5%) had NOTCH1 mutations, and 19 FBXW7 mutations. The gene discussed is NOTCH1; the disease is acute lymphoblastic leukemia.