genetic polymorphism


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Related to genetic polymorphism: Single nucleotide polymorphism

polymorphism

 [pol″e-mor´fizm]
the ability to exist in several different forms.
balanced polymorphism an equilibrium mixture of homozygotes and heterozygotes maintained by natural selection against both homozygotes.
genetic polymorphism the occurrence together in the same population of two or more genetically determined phenotypes in such proportions that the rarest of them cannot be maintained merely by recurrent mutation.
single nucleotide polymorphism (SNP) a genetic polymorphism between two genomes that is based on deletion, insertion, or exchange of a single nucleotide.

ge·net·ic pol·y·mor·phism

the occurrence in the same population of multiple discrete alletic states of which at least two have high frequency (conventionally of 1% or more).

genetic polymorphism

the recurrence within a population of two or more discontinuous genetic variants of a specific trait in such proportions that they cannot be maintained simply by mutation. Examples include the sickle cell trait, the Rh factor, and the blood groups. Compare balanced polymorphism.

genetic polymorphism

or

polymorphism

the presence in a population of two or more MORPHS, produced when different alleles of a gene occur in the same population and the rarest allele is not maintained merely by repeated MUTATION (i.e. has a frequency higher than, say, 0.05%). Such a definition excludes continuously variable characters such as height or skin colour in humans, but the human blood groups are classic examples, where single genes have two or more alleles, producing different antigenic phenotypes. A genetic polymorphism can be maintained by several mechanisms such as heterozygous advantage or FREQUENCY-DEPENDENT SELECTION, and can be stable over several generations (a BALANCED POLYMORPHISM) or may become ‘transient’ as when the environment changes; see, for example, SICKLE-CELL ANAEMIA.
References in periodicals archive ?
The availability in the ESCH database of a group of subjects genotyped for GSTM1 and GSTT1 genes in three national laboratories allowed us to address the question if these genetic polymorphisms can modify the strength of the association between CA and cancer risk.
Glutathione S-transferase M1 and T1 genetic polymorphisms were determined using DNA extracted from participant buccal washings.
The proton pump inhibitor omeprazole, used in the short-term treatment of active duodenal ulcer and esophagitis, is primarily metabolized by the CYP2C19 enzyme, and thus its metabolism is subject to this genetic polymorphism.
Dietary selenium intake, aldehyde dehydrogenase-2 and X-ray repair cross-complementing 1 genetic polymorphisms, and the risk of esophageal squamous cell carcinoma.
Genetic polymorphism of the calcium sensitive casein in Sicilian Girgentana and Argentata dell'Etna goat breeds.
Data from the present study, however, provide a basis for future studies of the role genetic polymorphisms of SV and presynaptic plasma membrane proteins which play in the etiology of AD.
In this issue, Mitra et al (1) report the biology of human cancer in relation to genetic polymorphisms.
Genetic polymorphism of PON1 at Q192R and L55M modulated paraoxonase activity against paraoxon and not against phenyl acetate.
In this situation, however, we can surmise that if the total population variance attributable to the genetic polymorphism is <4% it would not be statistically defensible to partition, because partitioning into 3 groups leads to larger uncertainty around cutoffs than seen with 2 groups.
To our knowledge this is the first time to investigate the correlation between genetic polymorphism of GSTM1 and GSTP1 and lung cancer in Egyptian patients.
Genetic polymorphism of thiopurine methyltransferase and its clinical relevance for childhood acute lymphoblastic leukemia.
Other molecular biology methods may be used to detect genetic polymorphisms, including direct sequencing (6), restriction fragment length polymorphism analysis (7), and single-strand conformation polymorphism analysis (8), but these methods are laborious and cumbersome, which is a major drawback for their routine use in clinical practice.