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Because they commonly involve more than one gene, the disorders caused by these large deletion and duplication mutations are often severe.
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.
Deletion Mutation Definition. A deletion mutation is a mistake in the DNA replication process which removes nucleotides from the genome. A deletion mutation can remove a single nucleotide, or entire sequences of nucleotides.
Genes contain instructions that determine how the body is supposed to look and function. (See Genes and Chromosomes for a discussion about genetics.) When parts of chromosomes are missing, a number of syndromes can occur. These syndromes are called chromosomal deletion syndromes.
A deletion, as related to genomics, is a type of mutation that involves the loss of one or more nucleotides from a segment of DNA. A deletion can involve the loss of any number of nucleotides, from a single nucleotide to an entire piece of a chromosome.
Deletions: A portion of the chromosome is missing or deleted. Duplications: A portion of the chromosome is duplicated, resulting in extra genetic material. Translocations: A portion of one chromosome is transferred to another chromosome.
There can be cases with one piece deleted at the end (terminal deletion), two deletions – one deleted within the chromosome, and one on the end – (interstitial deletion). Microdeletions also occur when the deletions in the chromosomes are too small to be detected.
The result is the deletion of a DNA sequence in one chromosome, and the insertion of a DNA sequence in the other chromosome.
Syndromes involving smaller deletions (and additions) that affect one or more contiguous genes on a chromosome and are not visible on karyotyping are considered microdeletion and duplication syndromes.
Mutations can also influence the phenotype of an organism. This tutorial looks at the effects of chromosomal mutations, such as nondisjunction, deletion, and duplication.