Copy-number variation

Copy number variation ( CNV short, German copy number variation ) refers to a form of structural variation in the genome ( SV for short, English structural variation), generates the deviations of the number of copies of a particular DNA segment within a genome. Approx. 30.000 Copy Number Variants ( CNVs ) are known in humans. It was thought until recently that genes in the genome are present usually in two copies ( one copy per chromosome set ). However, some genes show a variation in gene copy number between different individuals. Thus, a gene may be present in only one copy number ( gene deletion ) or in more than three or four copies ( gene duplication ). Genes can also be completely absent ( homozygous gene deletion ). Similar to single nucleotide polymorphisms ( SNPs or ) may also be due to the presence or absence of CNVs individuals differ from each other clearly. CNVs can have an impact on the predisposition to certain diseases. Compared with SNPs generate CNVs a larger number of genetic differences between individuals when ( nucleotides) specifies the number of records affected by CNVs DNA building blocks to reason.

For CRF in the genomes based identification techniques as well as DNA sequencing, and in particular methods of both microarray "second generation sequencing " is used. An analysis of data of a pilot study of the 1000 Genome Project allowed the identification of 28,000 CNVs in the genomes of 185 individuals with four different DNA sequence based analysis. These four methods include end pair sequencing and the bioinformatic analysis ( paired- end mapping), the direct Alinierung of DNA sequences via the terminals ( or " breakpoints " ) of CNVs (split -read analysis ), the sequence depth analysis (read- depth analysis) and the use of computational methods for sequence assembly (sequence assembly).

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