1. There are serious doubts about accuracy of diagnosis, well rooted out here:
I suspect the ME/CFS prevalence in this cohort was largely based on the CDC symptom inventory. This Wiki for the Lifelines project provides some more information:
https://wiki.lifelines.nl/doku.php?id=cfs_diagnostic_score
https://wiki.lifelines.nl/doku.php?id=fatigue_cdc
So it's is basically chronic faitgue plus at least 4 out of 8 largely generic CDC/Fukuda symptoms, with no mandatory pem, whose assessment in any case is unclear. And no attempt to diagnose alternative causes of fatigue, which is the hardest and most important aspect of diagnosis
As
@ME/CFS Skeptic points out, the 4%+ prevalance adds to the doubt. This looks like a diagnosis of CF/poor health. It isn't surprising they find a substantial overlap with other disorders, probably similarly poorly diagnosed.
It looks like a big fuzzy mess inevitably overlaps internally, but probably with little chance of finding out anything meaningful.
Looking at it another way:
DecodeME's grant application cited the Utah registry study that found an ME/CFS heritability of (I think) 0.12; respectable, but still pretty low on a 0-1 scale. That figure could include familial environmental factors, including behaviour, i.e. an unknown genetic contribution.
DecodeME itself will calculate genetic-only heritability. If that is similar to the Utah study, it will suggest that environmental factors are relatively low. Of course, this study is claiming that genetics is important.
But what are those shared genetic influences? At that stage, what would matter is which genes are implicated - what biology? Maybe it points to biological, not psychosocial factors. I'm not aware of any GWAS for, say, FM or IBS, but if there are, I expect Chris and co. will be looking at them, either in the main paper or later. At this point, we would have good data to debate the overlap between FD/ID and ME/CFS. Currently, we seem only to have unsafe data and a lot of speculation.
Wouldn't it be nice to have some good data and move on to discussing science, not pile up papers that sort of support the views of authors but are full of holes and take us nowhere?
Well, that's my bit of frustration coming out!