Diagnosis of allelic imbalances.

ln (allelic ratio) of the normal DNA − ln (allelic ratio) of the leukemic DNA was plotted for all patients and all microsatellite markers (except noninformative markers and markers showing complete LOH or biallelic losses). Note that ln (allelic ratio) = ln [(N2/N1)/(L2/L1)] = ln (N2/N1) − ln (L2/L1) and that the values are symmetrically distributed around 0 (representing the case N2/N1 = L2/L1). A total of 879 markers with allelic ratio values above 0.199 [upper cut-off level, calculated as 75% quartile + 3 × (75% quartile − median)] or below −0.207 [lower cut-off level, calculated as 25% quartile − 3 × (median − 25% quartile)] were assessed as harboring allelic imbalances (see Mosteller et al49 for rationale). All other ratios were scored as heterozygous (ie, normal).