Heteroduplex analysis with denaturing HPLC of mtDNA fragment 2762-3389 at 59°C. PB indicates peripheral blood; BM, bone marrow; and PRP, platelet-rich plasma. *Homoduplex peak representing homoduplex wild-type as well as homoduplex mutant mtDNA. The small shoulder in the homoduplex peak was also present in normal controls. **Heteroduplex peak representing the heteroduplex species formed by wild-type and mutant mtDNA strands after denaturation and slow renaturation of the PCR product. Since heteroduplex molecules contain a destabilizing physical “bubble” of the 2 DNA strands at the site of the mismatch, they denature at a lower temperature than the corresponding homoduplex. Because of the resulting increase in single-strandedness, heteroduplex molecules more easily desorb from the HPLC column bead surface and thus have a shorter retention time.