Lim-only 1 (LMO1) also known as T-cell translocation gene 1 (TTG-1) and Rhombotin 1 (RBTN-1) encodes a LIM domain transcriptional cofactor, and was originally identified at a chromosomal breakpoint in a T-acute lymphoblastic leukaemia (T-ALL) cell line bearing the t(11;14)(p15;q11) translocation.1, 2LMO1 is not normally expressed in T-cells, but the t(11;14)(p15;q11) juxtaposes LMO1 to gene regulatory elements within the T-cell receptor α/δ loci leading to ectopic expression in a T-lymphoid environment. The gene discussed is LMO1; the disease is acute lymphoblastic leukemia.