The European Group for the Immunologic Classification of Leukemia previously described 4 of the most common patterns of expression: pro-T (cCD3+, sCD3−, CD1a−, CD2+, CD5−, CD7+, CD34−), pre-T/immature (cCD3+, sCD3−, CD1a−, CD2+, CD5+, CD7+, CD34−), cortical T (cCD3+, sCD3+/−, CD1a+, CD2+, CD5+, CD7+, CD34−), and mature-T (cCD3+, sCD3+, CD1a− CD2+, CD5+, CD7+, CD34−) [26]. This evidence concerns the gene CD5 and leukemia.