Detection of Mutations in Mitochondrial DNA by Droplet Digital PCR.

Mutations in mitochondrial DNA (mtDNA) may result in various pathological processes. Detection of mutant mtDNAs is a problem for diagnostic practice that is complicated by heteroplasmy - a phenomenon of the inferring presence of at least two allelic variants of the mitochondrial genome. Also, the level of heteroplasmy largely determines the profile and severity of clinical manifestations. Here we discuss detection of mutations in heteroplasmic mtDNA using up-to-date methods that have not yet been introduced as routine clinical assays. These methods can be used for detecting mutations in mtDNA to verify diagnosis of "mitochondrial disease", studying dynamics of mutant mtDNA in body tissues of patients, as well as investigating structural features of mtDNAs. Original data on allele-specific discrimination of m.11778G>A mutation by droplet digital PCR are presented, which demonstrate an opportunity for simultaneous detection and quantitative assessment of mutations in mtDNAs.

[The association of the mitochondrial DNA oriB variants with metabolic syndrome]. / Rol' polimorfizma saita oriB mitokhondrial'noi DNK v metabolicheskom sindrome.

Different genes are involved in the development of pathology and formation the metabolic syndrome (MS) phenotype. In the literature, there is a data connection to the site oriB polymorphisms of mitochondrial DNA (mtDNA), known as 16184-16193 polycytosine tract, with insulin resistance, type 2 diabetes (T2DM) and other metabolic abnormalities in different ethnic populations. It is supposed that for certain polymorphisms at this site decreases mtDNA copy number in the cells. In this study, we have identified different allelic variants of the mtDNA oriB site in MS patients (n=106) and healthy individuals (n=71) using capillary sequencing, and determined the amount of mtDNA copy blood leukocytes by droplet digital polymerase chain reaction (ddPCR). The continuous polycytosine tract was significantly more common in MS patients, and such a link was particularly strong in MS patients with type 2 diabetes (p<0.01). No significant correlation has been found between mtDNA copy number and the oriB site variants, but in general there is a tendency to decreased mtDNA copy number in MS patients.