Polygenic Risk Score is Absolutely Useless for Predicting Schizophrenia

 This Study  used the best polygenic risk score (PRS) to try and predict schizophrenia for a large group of individuals. Let's just cut to the chase, here:

For all outcomes investigated, the SCZ PRS did not improve the performance of predictive models, an observation that was generally robust to divergent case ascertainment strategies and the ancestral background of the study participants.

 At this point, it is denial to believe that PRS is ever going to have any real use for schizophrenia or other classified mental disorders. The reason for this is that these traits are not related to genetic variants. The entire premise of PRS is a flawed idea for behavioral genetics. Let me add that if you let your diagnosis be influenced by polygenic scores (which you shouldn't based on this study, but you know how these go), then you will create a self-fulfilling prophecy of PRS predicting schizophrenia. 

My Review of Kathryn Paige Harden's "The Genetic Lottery "

Every few years, the scant evidence for genetic determinism will be promoted and sold in book form. In 2018, it was Robert Plomin’s “Blueprint.”  The latest comes from psychologist and behavior geneticist, Kathryn Paige Harden, with her new book: “The Genetic Lottery - Why DNA Matters for Social Equality.” From the title alone, one can see that she will be selling a version of genetic determinism with a heart. To her credit, in contrast to Plomin, Harden addresses the ramifications of behavioral genetics’ historical association with eugenics in some detail, but her book is otherwise similar in substance to Blueprint (despite her own negative review of Blueprint). Both books spin polygenic scores as a savior for the failing field of behavioral genetics, with the dubious suggestion that these results are “causal.”  

In Plomin’s case, his fanaticism for polygenic scores could be written off as wishful thinking for a man at the end of his career, touting a perceived future of ever improving polygenic prediction. Harden, on the other hand, has had a few years to see the hype dwindle, with study after study noting the limitations of such scores. 

Harden’s primary focus is what is referred to as “educational attainment,” basically a simple measurement of how far someone goes in school, viewing it as a trait with some genetic basis. In truth, this “trait” is a bit of subterfuge, serving as a proxy for intelligence, while avoiding some of the controversy surrounding genetic studies of IQ (and their association with books like Charles Murray’s, “The Bell Curve”). 

Harden's writing style at times involves condescending oversimplification through analogy: “If a gene is a recipe, then your genome -  all the DNA contained in all of your cells - is a large collection of recipes, an enormous cookbook.” This quaint presentation of the subject suggests that she is targeting a lay audience, but I question whether those not already familiar with this kind of research would find this book engaging and these analogies do not appear to clarify the subject in a more comprehensible manner.

Books of this nature generally have the same two issues to tackle and Harden’s is no exception. The first is to sell the scientific evidence related to claims of a genetic basis for educational attainment and other behavioral traits. The second relates to the ethical and practical implications of this research. I will address her treatment of both issues here, beginning with the latter.