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Gene duplications can arise as products of several types of errors in DNA replication and repair machinery as well as through fortuitous capture by selfish genetic elements. Common sources of gene duplications include ectopic recombination , retrotransposition event, aneuploidy , polyploidy , and replication slippage .
Evolution by gene duplication is an event by which a gene or part of a gene can have two identical copies that can not be distinguished from each other. This phenomenon is understood to be an important source of novelty in evolution, providing for an expanded repertoire of molecular activities.
Repeated sequences (also known as repetitive elements, repeating units or repeats) are short or long patterns that occur in multiple copies throughout the genome.In many organisms, a significant fraction of the genomic DNA is repetitive, with over two-thirds of the sequence consisting of repetitive elements in humans. [1]
The study of human genetic variation has evolutionary significance and medical applications. It can help scientists reconstruct and understand patterns of past human migration. In medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in certain population groups.
An inversion occurs when a chromosome undergoes a two breaks within the chromosomal arm, and the segment between the two breaks inserts itself in the opposite direction in the same chromosome arm. The breakpoints of inversions often happen in regions of repetitive nucleotides, and the regions may be reused in other inversions. [ 1 ]
Structural variation is an important type of human genetic variation that contributes to phenotypic diversity. [2] There are microscopic and submicroscopic structural variants which include deletions, duplications, and large copy number variants as well as insertions, inversions, and translocations. [1]
The mode of duplication by which redundancy occurs has been found to impact the classifications in breast cancer disposition genes. [19] Gross duplications complicate clinical interpretation because it is difficult to discern if they occur in tandem. Recent methods, like DNA breakpoint assay, have been used to determine tandem status. [19]
Polyploid speciation is commonly observed in plants because their nature allows them to support genome duplications. Polyploids are considered a new species because the occurrence of a whole genome duplication imposes post-zygotic barriers, which enable reproductive isolation between parent populations and hybrid offspring.