Is This a Successful Study for Bipolar Genetics? That's how they are billing it.

A "new" GWAS came out for Bipolar Disorder. As yet, I have only seen the abstract, but I wonder whether I need to see more? Let me comment on a few things:

"Eight of the 19 variants that were genome-wide significant (P < 5 × 10−8) in the discovery GWAS were not genome-wide significant in the combined analysis, consistent with small effect sizes and limited power but also with genetic heterogeneity."

Is that really what it's consistent with? If you have variants that were found to be significant in previous studies and you include the data from those studies in your current study, even if the effect size was small (and, the power now increased), you should expect most of them to retain significance, even if they weren't significant in the new data set independently. The fact that half of them have lost significance is a good indication that most or all of them were false positives to begin with. Moreover, once again, why not do an independent GWAS (I'm assuming they did not) of the new data and compare it to the old data?
Now let's look at the very next sentence:

Publishing Bias, but look a little closer

Over the past few decades, hundreds of "genetic links" have been "found", largely through genome-wide association studies, in which the researchers look at hundreds of different genetic loci to find 1 or 2 that are more highly correlated in their study group vs. their control group, whether this be for intelligence, schizophrenia, "novelty-seeking", etc.  As I've already mentioned, these studies tend to crank out a lot of false positives, which even the scientific community is coming to terms with, as can be seen here.  So, since almost all of the hundreds of alleged genetic linkages have not been replicated, we might expect to see a lot of studies in the literature that give negative results, refuting the previous positive results.   In actuality, although we occasionally do see that, it is the exception rather than the rule.

Bipolar Disorder. What are we really talking about?

As a clinical psychiatrist, I have a lot of thoughts about studies, genetic or otherwise, of the various mental disorders.  Before we even look at the merits of a genetic association study for a particular mental disorder, I think it's worth looking at a few diagnoses and some of the possible pitfalls of doing a study specific to a diagnosis.  Some diagnoses might have a more "organic" flavor to them (Schizophrenia, Schizoaffective Disorder, Bipolar Disorder) and one might assume that they would lend themselves better to genetic association study.  So I'll start with one of those: Bipolar Disorder.