- Endophenotype
Endophenotype is a psychiatric concept and a special kind of
biomarker . The purpose of the concept is to divide behaviouralsymptom s into more stablephenotypes with a cleargenetic 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".
Definition
They make five demands a biomarker or cognitive marker must fulfill to be called an endophenotype:
# The endophenotype is associated with illness in the population.
# The endophenotype is heritable.
# The endophenotype is primarily state-independent (manifests in an individual whether or not illness is active).
# 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.
# The endophenotype found in affected family members is found in nonaffected family members at a higher rate than in the general population.For schizophrenia
In the case of
schizophrenia , the overt symptom could be apsychosis , but the underlying phenotypes are, for example, a lack of sensory gating and a decline inworking memory . Both of these traits have a clear genetic component and can thus be called endophenotypes. [Gottesman I & Gould T: The Endophenotype Concept in Psychiatry: Etymology and Strategic Intentions, 2003 ]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 theserotonin receptor 5-HT1B, known to be relevant in aggressive behaviors. [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.]ee also
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Biomarker References
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