A prospective study of residual-disease monitoring of the ALL1/AF4 transcript in patients with t(4;11) acute lymphoblastic leukemia..     ///     Twenty-five patients (22 adults and 3 infants) with ALL1/AF4-positive acute lymphoblastic leukemia (ALL) were prospectively monitored by reverse transcriptase-polymerase chain reaction (RT-PCR) between January 1992 and July 1999. 