Endophenotype

In genetic epidemiology, endophenotype (or intermediate phenotype[1]) is a term used to separate behavioral symptoms into more stable phenotypes with a clear genetic connection. By seeing the EP notion as a special case of a larger collection of multivariate genetic models, which may be fitted using currently accessible methodology, it is possible to maximize its valuable potential lessons for etiological study in psychiatric disorders.[2] The concept was coined by Bernard John and Kenneth R. Lewis in a 1966 paper attempting to explain the geographic distribution of grasshoppers. They claimed that the particular geographic distribution could not be explained by the obvious and external "exophenotype" of the grasshoppers, but instead must be explained by their microscopic and internal "endophenotype".[3] The endophenotype idea represents the influence of two important conceptual currents in biology and psychology research. An adequate technology would be required to perceive the endophenotype, which represents an unobservable latent entity that cannot be directly observed with the unaided naked eye. In the investigation of anxiety and affective disorders, the endophenotype idea has gained popularity.[4]

The next major use of the term was in psychiatric genetics, to bridge the gap between high-level symptom presentation and low-level genetic variability, such as single nucleotide polymorphisms.[5] It is therefore more applicable to more heritable disorders, such as bipolar disorder and schizophrenia.[6] Through their impact on the growth and operation of the vital components of the nervous system, such as neurons, transmitter systems, and neural networks, genes have an impact on complex behavior. Therefore, heritable differences in mental abilities may be caused by changes in the code describing the shape and operation of the underlying neural network. One significant expression of this idea is believed to be the many cognitive deficiencies seen in ADHD, making them ideal candidates for an endophenotype approach.[7] Since then, the concept has expanded to many other fields, such as the study of ADHD,[8] addiction,[9] Alzheimer's disease,[10] obesity[11] and cystic fibrosis.[12] Some other terms which have a similar meaning but do not stress the genetic connection as highly are "intermediate phenotype", "biological marker", "subclinical trait", "vulnerability marker", and "cognitive marker".[13][14] The strength of an endophenotype is its ability to differentiate between potential diagnoses that present with similar symptoms.[15]

  1. ^ Preston, Gilbert A.; Weinberger, Daniel R. (June 2005). "Intermediate phenotypes in schizophrenia: a selective review". Dialogues in Clinical Neuroscience. 7 (2): 165–179. doi:10.31887/DCNS.2005.7.2/gpreston. ISSN 1294-8322. PMC 3181731. PMID 16262211.
  2. ^ Kendler, K S; Neale, M C (2010-08-15). "Endophenotype: a conceptual analysis". Molecular Psychiatry. 15 (8): 789–797. doi:10.1038/mp.2010.8. ISSN 1359-4184. PMC 2909487. PMID 20142819.
  3. ^ John B, Lewis KR (May 1966). "Chromosome variability and geographic distribution in insects". Science. 152 (3723): 711–21. Bibcode:1966Sci...152..711J. doi:10.1126/science.152.3723.711. PMID 17797432.
  4. ^ Lenzenweger, Mark F. (2013-03-06). "ENDOPHENOTYPE, INTERMEDIATE PHENOTYPE, BIOMARKER: DEFINITIONS, CONCEPT COMPARISONS, CLARIFICATIONS: The Cutting Edge: Endophenotype, Intermediate Phenotype, and Biomarker". Depression and Anxiety. 30 (3): 185–189. doi:10.1002/da.22042. PMID 23325718. S2CID 6848146.
  5. ^ Gottesman II, Gould TD (April 2003). "The endophenotype concept in psychiatry: etymology and strategic intentions". The American Journal of Psychiatry. 160 (4): 636–45. doi:10.1176/appi.ajp.160.4.636. PMID 12668349.
  6. ^ Greenwood TA, Braff DL, Light GA, Cadenhead KS, Calkins ME, Dobie DJ, et al. (November 2007). "Initial heritability analyses of endophenotypic measures for schizophrenia: the consortium on the genetics of schizophrenia". Archives of General Psychiatry. 64 (11): 1242–50. doi:10.1001/archpsyc.64.11.1242. PMC 10588564. PMID 17984393.
  7. ^ Goos, Lisa M.; Crosbie, Jennifer; Payne, Shalaine; Schachar, Russell (2009-06-01). "Validation and Extension of the Endophenotype Model in ADHD Patterns of Inheritance in a Family Study of Inhibitory Control". American Journal of Psychiatry. 166 (6): 711–717. doi:10.1176/appi.ajp.2009.08040621. ISSN 0002-953X. PMID 19448185.
  8. ^ Alderson RM, Rapport MD, Hudec KL, Sarver DE, Kofler MJ (May 2010). "Competing core processes in attention-deficit/hyperactivity disorder (ADHD): do working memory deficiencies underlie behavioral inhibition deficits?". Journal of Abnormal Child Psychology. 38 (4): 497–507. doi:10.1007/s10802-010-9387-0. PMID 20140491. S2CID 1641972.
  9. ^ Ersche KD, Jones PS, Williams GB, Turton AJ, Robbins TW, Bullmore ET (February 2012). "Abnormal brain structure implicated in stimulant drug addiction". Science. 335 (6068): 601–4. Bibcode:2012Sci...335..601E. doi:10.1126/science.1214463. PMID 22301321. S2CID 13958119.
  10. ^ Reitz C, Mayeux R (November 2009). "Endophenotypes in normal brain morphology and Alzheimer's disease: a review". Neuroscience. 164 (1): 174–90. doi:10.1016/j.neuroscience.2009.04.006. PMC 2812814. PMID 19362127.
  11. ^ Comuzzie AG, Funahashi T, Sonnenberg G, Martin LJ, Jacob HJ, Black AE, et al. (September 2001). "The genetic basis of plasma variation in adiponectin, a global endophenotype for obesity and the metabolic syndrome". The Journal of Clinical Endocrinology and Metabolism. 86 (9): 4321–5. doi:10.1210/jcem.86.9.7878. PMID 11549668.
  12. ^ Stanke F, Hedtfeld S, Becker T, Tümmler B (May 2011). "An association study on contrasting cystic fibrosis endophenotypes recognizes KRT8 but not KRT18 as a modifier of cystic fibrosis disease severity and CFTR mediated residual chloride secretion". BMC Medical Genetics. 12: 62. doi:10.1186/1471-2350-12-62. PMC 3107781. PMID 21548936.
  13. ^ Lenzenweger MF (March 2013). "Endophenotype, intermediate phenotype, biomarker: definitions, concept comparisons, clarifications". Depression and Anxiety. 30 (3): 185–9. doi:10.1002/da.22042. PMID 23325718. S2CID 6848146.
  14. ^ Lenzenweger MF (November 2013). "Thinking clearly about the endophenotype-intermediate phenotype-biomarker distinctions in developmental psychopathology research". Development and Psychopathology. 25 (4 Pt 2): 1347–57. doi:10.1017/S0954579413000655. PMID 24342844. S2CID 13629102.
  15. ^ Brotman MA, Guyer AE, Lawson ES, Horsey SE, Rich BA, Dickstein DP, et al. (March 2008). "Facial emotion labeling deficits in children and adolescents at risk for bipolar disorder". The American Journal of Psychiatry. 165 (3): 385–9. doi:10.1176/appi.ajp.2007.06122050. PMID 18245180.