Trait
In genetics, a trait refers to any genetically determined characteristic. In technical terms, a genetic trait is amenable to segregation analysis rather than quantitative analysis. A dominant lethal trait is a trait that is expressed if present in the genome and therefore precludes having descendants. All such cases must necessarily be sporadic and must represent new mutations, not inherited ones (because a potential parent with the trait would die before being able to pass it along). A mendelian trait is one that segregates in accordance with the laws of genetics set forth by Gregor Mendel. Sickle cell trait is a mendelian trait. It refers to the situation in which a person has one copy (and one copy only) of the gene for sickle cell but does not have sickle cell disease (which requires two copies of the sickle cell gene). If two people with sickle cell trait have children together, each of their children has a one in four chance (25%) of having sickle cell disease. A nonpenetrant trait is a genetic trait that is in the genome but does not manifest itself in the individual. By contrast, a penetrant trait is one that manifests itself. If, for example, if 100 people have a particular genetic trait but only 80 of them express it, the penetrance of that trait is 80%.
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A qualitative characteristic; a discrete attribute as contrasted with metric character. A t. is amenable to segregation rather than quantitative analysis; it is an attribute of phenotype, not of genotype. [Fr. from L. tractus, a drawing out, extension]
- Bombay t. Bombay phenomenon.
- categorical t. in genetics, a feature that can conveniently and effectively be analyzed by sorting into classes either because there is no satisfactory way of measuring it (as with blood group s) or because it falls into natural classes so that the variation among classes far exceeds that within classes ( e.g., the phenotypic effects of many enzyme polymorphisms); existence of categories suggests but does not prove the operation of a major, simple, underlying cause. SYN: qualitative t..
- chromosomal t. a t. dependent on a recurrent chromosomal aberration.
- dominant t. an outstanding mental or physical characteristic. See dominance of traits.
- dominant lethal t. t., expressed in the phenotype if present in the genotype, that precludes having descendants. All such cases are necessarily sporadic and must represent new mutations as the usual methods of classical genetics provide no means of demonstrating any genetic component whatsoever, except for tenuous arguments such as advanced paternal age. Molecular biology may help although the methods may be tedious; if there is an epistatic gene that may mask the t., the logic is more tractable, though complex.
- galtonian t. a quantitative genetic t. due to contributions from many more of less equally important loci that resembles a continuous t..
- intermediate t. a measurable t. in which there is some evidence of the operation of a simple major cause, but in which the variation within the putative categories is such as to cause overlap and hence ambiguity in classification of any particular reading.
- liminal t. SYN: threshold t..
- marker t. a t. that may be of little importance in itself but which by association, linkage, or other means facilitates the detection, anticipation, or understanding of a disease or (for genetic diseases) the localization of the causative gene on the karyotype.
- mendelian t. a categorical t. that segregates in accordance with a single-locus genetic system.
- nonpenetrant t. a genetic t. that is not phenotypically manifest because of nongenetic factors; it therefore does not include recessivity, epistasis, hypostasis, or parastasis but does include environmental factors and pure random effects such as lyonization.
- penetrant t. a t. that in the appropriate genotypes is phenotypically manifest; strictly, it is the t. that is penetrant, not the gene. See penetrance.
- qualitative t. SYN: categorical t..
- recessive t. dominance of traits.
- sickle cell t. the heterozygous state of the gene for hemoglobin S in sickle cell anemia.
- threshold t. a t. that falls into natural groups that originate not in categorically distinct causes but in whether or not the outcome attains critical values; e.g., gallstones may result from a categorical cause or from unusual levels of causal factors that themselves show no evidence of grouping. SYN: liminal t..

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trait 'trāt, Brit usu 'trā n an inherited characteristic

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(trāt) 1. any genetically determined characteristic; see also entries under character, gene, and inheritance. 2. sometimes, more specifically, the condition prevailing in the heterozygous state of a recessive disorder, as in sickle cell anemia. 3. a distinctive behavior pattern.

Medical dictionary. 2011.

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  • trait — 1. (trè ; le t ne se lie pas ; au pluriel, l s se lie : des trè z irréguliers) s. m. 1°   Action de tirer une voiture, un chariot. 2°   Corde ou lanière en cuir par laquelle les chevaux tirent une voiture. 3°   Plusieurs bateaux qu on attache… …   Dictionnaire de la Langue Française d'Émile Littré

  • Trait — may refer to: * Trait, a characteristic or property of some entity. * Biological traits, which involve genes and characteristics of organisms. * Trait theory, an approach to the psychological study of personality.In computing * Trait class, a… …   Wikipedia

  • Trait — Trait, n. [F., fr. L. tractus, fr. trahere to draw. See {Trace}, v., and cf. {Tract} a region, {Trace} a strap, {Tret}.] [1913 Webster] 1. A stroke; a touch. [1913 Webster] By this single trait Homer makes an essential difference between the… …   The Collaborative International Dictionary of English

  • Trait — steht für: Trait (Fluss), ein Fluss in Frankreich, Nebenfluss des Aron Trait (Programmierung), eine besondere Variante eines Mixins, welche z.B. in der Programmiersprache Scala genutzt werden kann in der Psychologie die Persönlichkeitseigenschaft …   Deutsch Wikipedia

  • Trait —   [treɪ(t); englisch »Zug«] der, (s)/ s, Psychologie: relativ unveränderlicher Grundzug der Persönlichkeit; in der faktorenanalytischen Theorie werden die Wesenszüge grundsätzlich in komplexe allgemeine Traits und persönliche Traits unterteilt,… …   Universal-Lexikon

  • Trait — [treit] das; s <aus engl. trait »Zug, Eigenheit«, dies über gleichbed. fr. trait aus lat. tractus zu trahere »ziehen«> Bez. für eine weitgehend stabil gedachte Charaktereigenschaft od. ein Verhaltensmerkmal einer Person (Psychol.) …   Das große Fremdwörterbuch

  • trăit — TRĂÍT s.n. (Rar) Faptul de a trăi. – v. trăi. Trimis de LauraGellner, 13.09.2007. Sursa: DEX 98  trăít s. n. Trimis de siveco, 10.08.2004. Sursa: Dicţionar ortografic …   Dicționar Român

  • trait — [treı, treıt US treıt] n [Date: 1500 1600; : French; Origin: act of pulling, trait , from Latin tractus; TRACT] formal a particular quality in someone s character personality/character traits ▪ a mental illness associated with particular… …   Dictionary of contemporary English

  • trait — (n.) late 15c., shot, missiles; later a stroke, short line (1580s), from M.Fr. trait, from L. tractus draft, drawing, drawing out, later line drawn, feature, from pp. stem of trahere to pull, draw (see TRACT (Cf. tract) (1)). Sense of particular… …   Etymology dictionary

  • trait — ► NOUN 1) a distinguishing quality or characteristic. 2) a genetically determined characteristic. USAGE Trait has two pronunciations. The first, sounding like tray, is the traditional one (corresponding to its sound in French), but the newer one …   English terms dictionary

  • trait — trait. См. признак. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

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