Structural Variation Defined
The analysis of the human genome revealed many great insights. Perhaps one of the most interesting is the amount of genetic variation given that the difference in DNA sequences between any two individuals being only about 0.1%. Genetic variation is a broad term that includes differences as small as a single base pair to alterations in the number or structure of entire chromosomes. Structural variation in the genome refers to cytogenetically visible and submicroscopic variants, namely above 1 kb (2). SV is a modification in the organization of genetic material of varying sizes (3, 4). Common examples of SV are comprised of balanced forms, including inversions and translocations, as well as unbalanced forms, including small deletions and duplications (indels), large-scale copy number variants (CNV), and insertions.
Importance of SV in genome research
SV has been recognized as an important source of human genetic disease susceptibility. This recognition has come, in part, from the identification that the contribution of SV to the overall amount of genomic variation is greater than that of single base pair changes (1, 4, 5, 6). These genomic aberrations range from whole or partial chromosome abnormalities (trisomies, monosomies, translocations), microdeletion syndromes and Mendelian diseases, to more complex traits such as Crohn’s disease, cancer, autoimmune disease, and neurodevelopment disorders including autism spectrum disorders (ASD), schizophrenia, epilepsy, and Parkinson’s disease (7, 8, 9). Most of these diseases are not fully understood as a large number of SVs remain undiscovered or untranslated. Therefore, studies of SVs possess significant potential for new approaches to disease diagnosis and medical treatment.