Alterations of length heteroplasmy in mitochondrial DNA under various amplification conditions

There are several areas within mitochondrial DNA that show length heteroplasmy. If the heteroplasmy pattern is unique and consistent for each person, it may be used to support an interpretation of exclusion in identity testing. We investigated whether the length heteroplasmy pattern would be consistent under different amplification conditions. We also determined whether various amplification parameters would affect the homopolymeric cytosine stretches (C-stretch) in HV1. Monoclonal samples tended to be heteroplasmic after amplification. After several repetitions, C-stretch patterns of all samples were inconsistent even under the same amplification conditions. Increased PCR cycles and high template concentrations resulted in a more frequent heteroplasmic tendency. These amplification parameters seem to have little effect if samples are not long enough in C-stretch or total length of the segment from nt 16180 to nt 16193. It is suggested that the pattern of length heteroplasmy cannot be used as an additional polymorphic marker.