Comparison between patients who have acquired UPD 13q at relapse in the whole leukemic clone (patient 9) or as a subclone (patient 1). (A) Change in relative allele signal (RAS) values between diagnosis and relapse, for SNPs heterozygous at diagnosis in the region of LOH on chromosome 13 for patients 1 and 9. The same SNPs that are heterozygous at diagnosis shift RAS values at relapse, consistent with LOH. (B) Electropherogram showing PCR fragment quantitation of FLT3 wild type, at 329 base pairs, and the larger ITD fragment in patients 1 and 9.