LOH as clonal marker in ALL. PCR analysis in 1 B-ALL case (74) detected identical LOH patterns in leukemic cell DNA in 2 consecutive relapses (lanes 06/90 and 05/91, respectively). This was observed with 2 different microsatellite markers, respectively, on chromosome 3 (D3S1611) and 15 (D15S161). R, remission; Rel, relapse.