https://www.theatlantic.com/science/archive/2019/05/waste-1000-studies/589684/
After 20 years of research linking a single gene polymorphism to depression, a subsequent larger study appears to have debunked the link. In the meanwhile, thousands of papers of been written on this gene and the mechanism linking it to human depression.
One possibility is that the larger study failed to account for all of the myriad environmental variables associated with depression, or other genetic effects are masking whatever causal relationship exists. Another possibility is that the small study was too small, and the significant findings were artifactual.
These types of findings always raise the skeptics' question: If scientists are publishing soooo much crap, why should we trust them on global warming and evolution?
In reality, the opposite is true: scientists police themselves, hypotheses and theories are constantly being edited and corrected. It may turn out that this gene is critical. Increased scrutiny will be placed on studies emerging in this field, and the truth will out.
Did we really just spend 2 decades and hundreds of millions of dollars studying noise?
https://ajp.psychiatryonline.org/doi/10.1176/appi.ajp.2018.18070881
Even if that gene polymorphism turns out to have nothing to do with depression, it could still prove highly beneficial to medical science to find out exactly what it DOES do. So I say it should be studied until we find what it does even after if or when we discover it has nothing to do with depression.