PS280 Chapter Notes - Chapter 4: Epigenetics
Document Summary
Examination of concordance rates among twins has been seen as more accurate basis from which to infer genetic contributions to disorders, bc genetic similarity b/w twins is known. Ex identical twins (monozygotic) have inherited same genes from parents (share exact same genotype), whereas non-identifical twins (fraternal/dizygotic) share only half their genotype. If there is greater condordance for a disorder among monozygotic twins than among dizygotic twins, we can infer a genetic basis for the disorder. Hard to amass large sample size; only a little more than 1% of all children are twins, and only one in three of these are monozygotic. For any particular disorder, there will be even fewer twins to select from, since most disorders occur in only very small percentage of population. Schizophrenia occurs in only 1% of population, so its hard to find enough monozygotic twins where at least one has schizophrenia.
