mitoTree

Human mitochondrial DNA (mtDNA) is a double-stranded circular DNA which is present in a part of cells that are known as mitochondria. This kind of DNA is an essential marker in various scientific disciplines like population, evolutionary, medical and forensic genetics. mtDNA is inherited exclusively through the maternal line, meaning that the mtDNA is passed from the mother to all her children. Therefore, mtDNA is not unique but identical within the same maternal line and can not be used for individualization. However, mtDNA has some beneficial properties. Especially in cases of damaged or degraded samples, mtDNA can stand out due to its high stability and the higher abundance compared to nuclear DNA. Therefore, it became an important domain in forensic investigations that deal with e.g., ancient samples, burnt samples or samples obtained from disasters like Tsunamis. To perform a mtDNA analysis, the mtDNA of the sample is extracted and then sequenced. This sequence is a long string consisting of the letters A, C, G and T. Once, the sequence is obtained, it is compared to a reference sequence known as the revised Cambridge Reference Sequence or short rCRS. Through noting only the differences to the rCRS a mtDNA profile or so called mtDNA haplotype is obtained. Each haplotype can be classified into a haplogroup and about 5,400 different haplogroups are known so far. The totality of all haplogroups present the current resolution of human mtDNA diversity and this is displayed as a phylogenetic tree termed PhyloTree. Unfortunately, PhyloTree is not maintained anymore but at the same time, (mt)DNA sequencing technologies improved and the amount of mtDNA data available is continuously growing but not used. This backlog of unused mtDNA haplotypes cause problems in all disciplines that rely on mtDNA haplogrouping as they are limited by outdated data. PhyloTree does not reflect the actual depth of known phylogeny anymore, leading to vague classification of mtDNA haplotypes and provoking an uncontrolled development of new and ambiguous haplogroups. To solve all these problems and to keep up with ongoing developments, we want to introduce mitoTree. The main objective of the project is to use quality controlled mtDNA haplotypes to enhance our knowledge of human mtDNA phylogeny and global haplotype variation. We make use of special algorithms to process and analyze the large amounts of data. Simultaneously, we strive to prevent the unregulated development of self-introduced haplogroups and uncontrolled growth. mitoTree should serve as a novel and high-quality reference for improved mtDNA haplogrouping. In this context, we will extend and rearrange the phylogenetic tree and propose to implement a user- friendly and interactive graphical interface to facilitate the usage across different scientific areas.