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Deletion on a chromosome. In genetics, a deletion (also called gene deletion, deficiency, or deletion mutation) (sign: Δ) is a mutation (a genetic aberration) in which a part of a chromosome or a sequence of DNA is left out during DNA replication.
In genetics and especially genetic engineering, deletion mapping is a technique used to find out the mutation sites within a gene. The principle of deletion mapping involves crossing a strain which has a point mutation in a gene, with multiple strains who each carry a deletion in a different region of the same gene.
In immunology, clonal deletion is the process of removing T and B lymphocytes from the immune system repertoire. [1] [2] The process of clonal deletion helps prevent recognition and destruction of the self host cells, making it a type of negative selection. Ultimately, clonal deletion plays a role in central tolerance. [3]
A conditional gene knockout allows gene deletion in a tissue in a tissue specific manner. This is required in place of a gene knockout if the null mutation would lead to embryonic death, [13] or a specific tissue or cell type is of specific interest. This is done by introducing short sequences called loxP sites around the gene.
In immunology, clonal selection theory explains the functions of cells of the immune system (lymphocytes) in response to specific antigens invading the body. The concept was introduced by Australian doctor Frank Macfarlane Burnet in 1957, in an attempt to explain the great diversity of antibodies formed during initiation of the immune response .
There is a critical difference between deletion and CN-LOH, as the latter mechanism cannot be detected by comparative genomic hybridization (CGH)-based gene copy number counting, and requires allelic genotyping. Either way, LOH leaves only non-functioning alleles of the TSG, and the individual may go on to develop cancer.
An advantageous mutation can create an advantage for that organism and lead to the trait's being passed down from generation to generation, improving and benefiting the entire population. The scientific theory of evolution is greatly dependent on point mutations in cells. The theory explains the diversity and history of living organisms on Earth.
Gene knockdown is an experimental technique by which the expression of one or more of an organism's genes is reduced. The reduction can occur either through genetic modification or by treatment with a reagent such as a short DNA or RNA oligonucleotide that has a sequence complementary to either gene or an mRNA transcript.