Tspan7 [CD231, TM4SF2, A15 and T-cell acute lymphoblastic leukemia (T-ALL)-associated antigen I], located on human chromosome Xp11.4, was first discovered by Takagi et al (Takagi et al., 1995) in 1995 as a highly specific marker for adult T-ALL. This evidence concerns the gene TSPAN7 and T-cell acute lymphoblastic leukemia.