Endophenotype

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Endophenotype is a psychiatric concept and a special kind of biomarker. The purpose of the concept is to divide behavioural symptoms into more stable phenotypes with a clear genetic connection. The concept was originally borrowed by Gottesman & Shields from insect biology.

Other terms with similar meaning but not stressing the genetic connection are “intermediate phenotype,” “biological marker,” “subclinical trait,” “vulnerability marker,” and "cognitive marker".

Contents

[edit] Definition

They make five demands a biomarker or cognitive marker must fulfill to be called an endophenotype:

  1. The endophenotype is associated with illness in the population.
  2. The endophenotype is heritable.
  3. The endophenotype is primarily state-independent (manifests in an individual whether or not illness is active).
  4. Within families, endophenotype and illness co-segregate. Subsequently, an additional criterion that may be useful for identifying endophenotypes of diseases that display complex inheritance patterns was suggested.
  5. The endophenotype found in affected family members is found in nonaffected family members at a higher rate than in the general population.

[edit] For schizophrenia

In the case of schizophrenia, the overt symptom could be a psychosis, but the underlying phenotypes are, for example, a lack of sensory gating and a decline in working memory. Both of these traits have a clear genetic component and can thus be called endophenotypes.[1]

[edit] For suicide

The endophenotype concept has also been used in suicide studies. A tentative endophenotype between the phenotype of completed suicide and the genetic basis is impulsive-aggressive tendencies. The genetic basis of the trait has been suggested to be the gene coding for the serotonin receptor 5-HT1B, known to be relevant in aggressive behaviors.[2]

[edit] See also

[edit] References

  1. ^ Gottesman I & Gould T: The Endophenotype Concept in Psychiatry: Etymology and Strategic Intentions, 2003
  2. ^ Zouk, H., McGirr, A., Lebel, V., Benkelfat, C., Rouleau, G. & Turecki, G.: (2007) The Effect of Genetic Variation of the Serotonin 1B Receptor Gene on Impulsive Aggressive Behavior and Suicide. American Journal of Medical Genetics Part B. Vol 144, pp 996-1002.
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