Deletion mutations

Low levels or absence of adenosine deaminase (ADA) is associated with one form of severe combined immunodeficiency disease (SCID) characterized by B-andT-lymphocyte dysfunction due to toxic effects of deoxyadenosine (HI9). Most patients present as infants with failure to thrive, repeated infections, severe lymphopenia, and defective cellular and humoral immunity. Disease severity is correlated with the degree of deoxyadenosine nucleotide pool expansion and inactivation of S-adenosylhomocysteine hydrolase in red blood cells. Up to now, more than 40 mutations have been identified (A4, H20, S5, S6). The majority of the basic molecular defects underlying ADA deficiency of all clinical phenotypes are missense mutations. Nonsense mutations, deletions ranging from very large to single nucleotides, and splicing mutations have also been reported. It is likely that severe... 

The path to individualized therapy is complex and will ultimately require a combination of genomic and proteomic analyses, which will incorporate tumor characteristics and somatic events (mutation, deletion and amplification) in order to provide a complete... 

By using suitable primers, it is possible to use PCR to create point mutations, deletions and insertions of target DNA which greatly facilitates the analysis of gene expression and function. 

Therefore, the genetic lesions caused by a mutagen can be detected in assays for many genetic end points, including base-pair substitution and frameshift mutation, deletion, mitotic recombination or gene conversion, unscheduled DNA synthesis, sister chromatid exchange, and chromosomal aberration.170... 

In addition to site-directed mutations, deletion mutants that eliminated some, or all, of the linker domain have been produced for A. niger glucoamylase.173 Deletions of up to 30 amino acids from the C-terminus of the linker domain had no effect on the activity of either glucoamylase-I or glucoamylase-II.173... 

Frameshift Mutation. Deletion or insertion of a base or bases that alters the reading frame of the gene. In contrast to base substitution mutations where the mutation often has no consequence to the gene function or has only a partial effect on the gene function, a frameshift mutation completely changes the amino acid sequence downstream of the mutation site within a proteincoding gene. Thus, frameshift mutation is a severe type of mutation, which results in inactivation of the protein product most of the time. 

The next more complex type of mutation is referred to as an addition or deletion mutation. In a deletion mutation, one or more bases are removed from the DNA. In an addition mutation, one or more bases are added to the DNA. Addition mutations are also called insertion mutations. Deletion mutations are called small deletions if only a few bases are deleted from the DNA, or large deletions if many bases are deleted from the DNA. The same considerations hold for small-addition and large-addition mutations. 

Replication often produces changes in the chemical makeup of DNA. Many of these changes are easily repaired however, those alterations in the DNA base sequence that do not get repaired are referred to as mutations. There are various types of mutations including point mutations, deletions, and insertions. 

There are various types of mutations including point mutations, deletions, and insertions. 

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