Showing posts from April, 2016

Is a polygenic model of schizophrenia genetics really proven?

Response to “A joint history of the nature of genetic variation and the nature of schizophrenia”.*
Kenneth Kendler’s article on the nature of genetic variation and the nature of schizophrenia claims that theory and empirical evidence have proven the polygenic architecture of this disorder. In fact, both theory and data are entirely consistent with a very different model of high genetic heterogeneity, where the disorder is largely caused in individuals by one or a few mutations in any of a large number of genes, incorporating important and complex effects of genetic background.
KK provides a scholarly overview of the history of ideas in these intertwined fields1. While historically interesting, the early arguments between biometricians and Mendelians about continuous versus dichotomous traits conflate two distinct questions: (i) what type of genetic variation contributes to the gradual evolution of new species?, and (ii) what type of genetic variation causes disease? There is no reason t…