Direct quantification of mitochondrial DNA and its 4.9-kb common deletion without DNA purification

Quantitative analysis of mitochondrial DNA (mtDNA) and its common deletion (CD) are sensitive and early markers for mitochondrial mutations and suffering. However, the use of purified DNA can lead to quantification errors because of variable DNA extraction yields due to the significant differences in size and structure between genomic DNA (gDNA) and mtDNA. We report a real-time qPCR-based protocol directly on tissue lysate, without DNA extraction. This method, which allows both absolute and relative measure, increases the measuring accuracy of the mtDNA/gDNA ratio and leads to reliable and more reproducible results when measuring the deleted/total mtDNA ratio.