Clinical outcome and monitoring of minimal residual disease in patients with acute lymphoblastic leukemia expressing the MLL/ENL fusion gene..     ///    "The observed inconsistency between the clinical cure and the presence of detectable MLL/ENL transcript suggests the existence of a MLL/ENL-expressing ""preleukemia"" stem cells, similar to what demonstrated for the AML1/ETO-positive leukemia setting.. "    ///     We analyzed 12 MLL/ENL positive ALL patients consecutively diagnosed between 1999 and 2009.     ///    "Further, a MLL/ENL expression, not preceding a relapse, was detected several times during the follow-up of five long-survivors. "    ///    The minimal residual disease molecular monitoring showed that MLL/ENL status did not correlate with outcome.     ///    "At CR, a parallel RT-PCR evaluation of the MLL/ENL expression was available in 5 cases. "    ///    "Of these latter, 2 tested MLL/ENL-negative and 3 positive. "    ///    "The MLL/ENL fusion was identified in 4/150 (2.6%), 8/993 (0.8%), and 0/70 of pediatric, adult, and elderly patients, respectively. "    ///    "In conclusion, also in adults, the MLL/ENL fusion identifies a rare leukemic entity with a favorable prognosis. "