Shed hairs (telogen hairs) are common crime scene samples that have little to no nuclear DNA present. When nuclear DNA is too degraded or limited, mitochondrial DNA analysis becomes useful because there are more mitochondrial DNA copies in a cell than there are nuclear DNA. The conventional method of mitochondrial DNA analysis by Sanger Sequencing of the non-coding HVI and HVII regions is time consuming and costly. Further, it has limited discrimination power, analyzing only 10% of the mitochondrial genome. Sanger Sequencing can detect the presence of mixture, but cannot quantitatively resolve mixtures, such as heteroplasmy, which is the presence of wild-type and mutant mitochondrial DNA coexisting in the same person.
To overcome the challenges of Sanger Sequencing, we used targeted capture enrichment of the whole mitochondrial genome coupled with Next Generation Sequencing using the Illumina® MiSeq platform for better detection and quantification of germline heteroplasmy. This high-throughput, massively parallel sequencing (MPS) technique reduces the time and cost to sequence the whole mitochondrial genome. Because of the high sensitivity of the MPS method, we will be better able to detect and quantify low-level heteroplasmy within and outside of the HVI and HVII regions. The high coverage per base of the MPS technique will also give us more confidence in mutation calling.
In this project, we focused on characterizing germline heteroplasmy within and outside of the non-coding region of the mitochondrial genome in mother-offspring pairs. We analyzed DNA from buccal and telogen hair samples from 17 mother-offspring pairs for germline and analyzed the sequenced data using the NextGene® and GeneMarker®HTS software from SoftGenetics®.
(Publisher abstract provided.)