If You Can't Make it Happen for Schizophrenia

 This is an expansion of a previous Schizophrenia GWAS:

Mapping genomic loci prioritises genes and implicates synaptic biology in schizophrenia

This is the PGC schizophrenia study. We hadn't really had an update since 2014. It appears they buried the lead with the usual false optimism. They went from 36,000 cases in the previous study to 69,000 in this one. We have been promised that polygenic risk scores (PRS) would explain more and more of the "missing heritablity" as the study sizes increased. Well, in this case, the PRS variance explained went from 3.4% to ... 2.6%. Of course, that 3.4% was apparently an error anyway.They also admit that their previous calculation of 3.4%, often cited in other papers, was calculated in error and was probably lower. Is that to make it look like the 2.6% is not that bad?

The fact of the matter is that this is a very bad result. This is not even a within family calculation, which one might expect to be very close to 0%. I think at this point, getting 2 or 3 percent of the variance explained is essentially a null finding, and I challenge any authors who claim otherwise to compare it to obvious null traits.

I might have more to say about this related to the loci they say reached significance, but can't find the old PGC data to compare it with directly. In any case, the only thing that increasing N does is bolster the number of "significant" loci and I expect none of these loci will independently meet statistical significance in any other study.

What this study really suggests, when you take away the spin, is that the entire model of a polygenic mechanism for schizophrenia is pie in the sky. This points to a larger problem, which is that if any psychiatric trait should be due to a physical (genetic) cause, one would think schizophrenia would be a sure thing. If you can't make it happen for schizophrenia, good luck making it happen for dubious diagnoses like ADHD or really any other psychiatric trait.