Analysis of TEL deletions.

(A) Detection of LOH on chromosome 12p. Allotypes at 4 informative markers are shown for each twin pair at diagnosis (T1, T2) and twin 2 at remission (R). Both twins retain heterozygosity of marker D12577 and show LOH at markers D12S89 Δ D12S269. Twin 1 retains heterozygosity at marker D12S310, but twin 2 shows LOH. Deleted alleles are not entirely diminished because of the subclonal deletion of 12p in the leukemic cells. (B) Schematic representation of chromosome 12p showing position of microsatellite markers. The LOH restricted to T2 is shown by the arrow at D12S310. SCDR shows the shortest commonly deleted region.30 REM, remission DNA analysis (no LOH control).