"Well, all that shows is they have a genetic predisposition to having unhelpful beliefs".
Genes might predispose to beliefs through a biological mechanism. No problem. (Genes might predispose someone to the belief that they are weak if the genes encode for muscular dystrophy.)
But perhaps the strongest conclusion one can draw from PACE is that beliefs are not the problem in MECFS. So
they are not unhelpful. The trial showed that you may be able to talk people into thinking differently about their health, or at least talking as if they did, but it makes no difference to more objective measures of how they are. They didn't get better. So the flaw in the argument is the invocation of
unhelpful belief.
The BPS approach pivots on the idea that you can separate 'psychological' and 'social' causation from biological causation. Note that depression that is not explained as a reaction to circumstances is called "biological". Psychiatrists treat it as such. But "psychological" in the BPS sense is not psychiatric or mental, it is some causation that can be treated as outside biology. Genes are biology. So we expect biological depression to link to genes. We can also reasonably expect genes to determine how miserable someone becomes after being made redundant or losing a loved one.
But that still doesn't make reactive depression fit "BPS". Nobody is likely to say that your depression "is psychological" in a BPS sense. The BPS guru does not claim that someone isn't really depressed, and just have this mind set that they are miserable when really they are a bundle of fun. The psychodynamic therapist might claim that you believe everything is terrible when in fact it is fine and that that is the problem. But most of us in medicine long ago went over to the view that having an abnormally negative take on things is driven by biology - neurotransmitters, synapses, and so on.
If BPS people start scoffing at DecodeME and saying that, so what, lot of psychological illnesses show gene links, what I would say is that what they mean is psychiatric illness And if they are suggesting that MECFS is on a par with those why are MECFS patients dying of starvation because they are denied feeding support because their illness is seen as
not psychiatric but functtional or biopsychosocial. Why do people with psychiatric disorders get full on long term care and life support when MECFS patients are just sent home to die?
Whether or not MECFS is a psychiatric illness doesn't depend on causation, it depends on the presentation of the illness. And by and large we can say pretty clearly that it is not psychiatric because it does not involve disordered thought in the way that neuroses and psychoses do but, for instance, dementia and Parkinsonisn do not. It is not an illness of derangement, but it does interfere with people's cognition. So it isn't a psychiatric disorder and never looked like one. Whether it is a bioposychosocial disorder is a
completely different question, which
does depend on what you believe about causation, and one which PACE answered with a fairly clear No.