LMO2 and T-cell leukemia: It is well known that the recent gene therapy trials using retrovirus-mediated introduction of the common cytokine receptor gamma chain (γc; CD132) in X-linked severe combined immunodeficiency (X-SCID) patients resulted in the development of T-cell leukemia due to retroviral insertion at the LMO2 locus (Hacein-Bey-Abina et al., 2003; Hacein-Bey-Abina et al., 2008; Howe et al., 2008).