This is a very general technique called quantitative trait association mapping (such a locus is called a QTL). It's a technique that has been used for decades,

This is a very general technique called quantitative trait association mapping (such a locus is called a QTL). It's a technique that has been used for decades, back when we used genetic markers and linkage maps (no genomes). What's interesting about this work is simply the degree of difficulty finding QTLs for mental illness; it's not the only genetic factor, and not particularly strong, so the signal to noise is quite poor. It required assembling a high-quality data set to identify a locus. It's good work, but nothing revolutionary. Once you can start to pin down the genetic factors, it can make future work easier, so it does bode well.