Sensitivity of DHPLC for mosaic mutation detection. DHPLC tracing of the following mixtures of abnormal (purified neutrophil) DNA from ATMDS patient no. 2 with a 20 + 1G>A ATRX mutation and normal, wild-type ATRX DNA: 10% mutation-enriched DNA (from the patient's purified peripheral blood granulocytes) with 90% wild-type (cyan), 5% mutant DNA with 95% wild-type (green), 2.5% mutant DNA with 97.5% wild-type (red), and 100% wild-type DNA (purple). The left peak or “shoulder” represents DNA heteroduplexes, the larger central peak represents homoduplexes. Even 2.5% abnormal DNA is clearly differentiated from the pure wild-type DNA. If the peripheral blood granulocytes from the patient with ATMDS included the progeny of any residual normal clones (ie, if the granulocyte DNA was not 100% ATRX mutant), the actual mutant DNA would be even less than 2.5% and the sensitivity correspondingly greater.