Applications of MALDI-TOF MS to large-scale human mtDNA population-based studies

Analysis of the mitochondrial DNA variation in populations is commonly carried out in many fields of biomedical research. We propose the analysis of mitochondrial DNA coding region SNP (mtSNP) variation to a high level of phylogenetic resolution based on MALDI-TOF MS. The African phylogeny has been chosen to test the applicability of the technique but any other part of the worldwide phylogeny (or any other mtSNP panel) could be equally suitable for MALDI-TOF MS genotyping. SNP selection thus aimed to fully cover all the mtSNPs defining major and minor branches of the known African tree, including, macro-haplogroup L, and haplogroups M1, and U6. A total of 230 mtSNPs were finally selected. We used tests samples collected from two different African locations, namely, Mozambique and Chad Basin. Different internal genotyping controls and other indirect approaches (e.g. phylogenetic checking coupled with automatic sequencing) were used in order to evaluate the reproducibility of the technique, which resulted to be 100% using samples previously subjected to whole genome amplification. The advantages of the MALDI-TOF MS are also discussed in comparison with other popular methods such as minisequencing, highlighting its high-throughput nature, which is particularly suitable for case-control medical studies, forensic databasing or population and anthropological studies.