Somatic Genome Variations: First Steps Towards a Deeper Understanding of an Underappreciated Source of Biodiversity and Disease

Somatic Genome Variations: First Steps Towards a Deeper Understanding of an Underappreciated Source of Biodiversity and Disease Somatic Genome Variations (SGV) are referred to as intercellular variability of genomes in somatic tissues of the same organism. These can manifest as single-nucleotide changes, short DNA sequence changes (<1kb), short tandem repeat variations, retrotransposition of mobile genome elements (i.e. SINE and LINE), copy number variations and subchromosomal structural abnormalities (microdeletions, microduplications, inversions; >1kb), structural chromosome abnormalities observed at microscopic level (>2-5 Mb), alterations to chromosome morphology (i.e. fragile sites), aneuploidy (gain/loss of whole chromosomes), polyploidy (gain of haploid chromosome sets). Several lines of evidences have been reported that SGV can play a role in human biodiversity and disease. For instance, it is generally recognized that somatic genome changes produced by genomic and chromosomal instability are cancer-causing. However, related phenomena are rarely addressed in non-malignant tissues. Current genomics essentially uses technologies which operate with DNA isolated from a large pool of cells and analyzes interindividual genomic variations, whereas single-cell genomic approaches are much more rarely applied. This probably explains why SGV are significantly less appreciated. Nevertheless, previous biomedical research does provide initial data that (i) SGV appear to be widespread in human cell populations; (ii) intercellular genomic diversity seems to be associated with a number of neurological, psychiatric and immune diseases, chromosomal syndromes and cancers as well as appear to be involved in critical biological processes (intrauterine development, cell number regulation and aging); (iii) molecular cytogenetics does provide technical solutions for studying single-cell genome variations at molecular resolutions. Therefore, a need appears to exist for additional attention to an underappreciated area of single-cell genomics aimed at studying SGV.