Genome duplication is the process by which additional copies of the entire genome are generated, due to nondisjunction during meiosis. The resulting cells and organisms are polyploid – they contain more than two homologous sets of chromosomes.

Duplication is a type of mutation that involves the production of one or more copies of a gene or region of a chromosome. Gene and chromosome duplications occur in all organisms, though they are especially prominent among plants. Gene duplication is an important mechanism by which evolution occurs.

Gene duplication is the process by which a region of DNA coding for a gene is copied. Gene duplication can occur as the result of an error in recombination or through a retrotransposition event. Duplicate genes are often immune to the selective pressure under which genes normally exist.

Duplications typically arise from an event termed unequal crossing-over (recombination) that occurs between misaligned homologous chromosomes during meiosis (germ cell formation). The chance of this event happening is a function of the degree of sharing of repetitive elements between two chromosomes.

Like some deletions, duplications of some human chromosomes cause syndromes of phenotypic abnormalities. A person afflicted with a duplication syndrome has three copies of the duplicated region, whereas other chromosome regions are present in two copies as usual.

1q21. 1 microduplication is a chromosomal change in which a small amount of genetic material on chromosome 1 is abnormally copied (duplicated). The duplication occurs on the long (q) arm of the chromosome at a location designated q21. 1. Some people with a 1q21.

Mosaic trisomy 22 is characterized by an extra copy of the chromosome 22 (trisomy) in some of the body cell populations. This could be due to an error during the division of reproductive cells in one of the parents (mitotic nondisjunction) or during cellular division after fertilization (fetal mitosis).

Duplications are even less common, showing a prevalence of 0.7 per 10,000 births and representing ≍ 2% of all the chromosome abnormalities identified (Wellesley et al., 2012).

Potocki-Lupski syndrome is a condition that results from having an extra copy (duplication ) of a small piece of chromosome 17 in each cell. The duplication occurs on the short (p) arm of the chromosome at a position designated p11. 2. This condition is also known as 17p11.

Chromosome 15 likely contains 600 to 700 genes that provide instructions for making proteins. These proteins perform a variety of different roles in the body.

In some people with Prader-Willi syndrome, the loss of a gene called OCA2 is associated with unusually fair skin and light-colored hair . The OCA2 gene is located on the segment of chromosome 15 that is often deleted in people with this disorder.