Interesting study. Though the sample and matched control sizes (n=12) are quite small, the patients were carefully selected out of a bigger sample (n=231).
Volunteers with HIV and HepC were excluded. They selected specifically 12 white female subjects, 52 years or younger, non-obese, with no previous consumption of immunmodulators and only with a sudden viral onset. Furthermore, PEM > 24h, cognitive impairment, a low vitality, low social and/or physical functioning were required.
The authors themselfs say, though the sample size for this study was small, it was carefully selected and likely representative of sudden onset CFS. I cannot say anything about their statistical analyses (maybe we have an expert around?).
They found different DNA Methylation in overall 826 genes in four clusters, cellular processes, positive metabolic regulation, kinase activity and mostly in the the immune response. The majority were hypermethylated (> 60%), so inactivated in comparison to controls.
In my understanding this study has nothing to do with RichvanK's work. Methylation of the DNA activates or inactivates certain gens and their expression in relation to other bodily processes (like autoimmunity) and environmental factors (like an infection or stress). It is not about the methylation process itself.
Here some quotes, I found interesting.
"Differentially methylated genes related to immune cell regulation showed an increased proportion of hypomethylated CpG sites among CFS patients, particularly in promoters and in gene regulatory elements."
"Hypomethylated CpG sites were significantly enriched in promoters and gene regulatory elements of genes related to immune signaling. It is possible that these immune genes may show increased transcript abundance or increased transcriptional potential, at least among the CFS group selected in this study, as promoter hypomethylation is generally associated with an increase in gene expression."
"Nevertheless, our data provide evidence that epigenetic variation in CFS may be distinct, at least in part, from related disorders with an immunological component. For example, epigenomic analysis of whole blood in fibromyalgia (FM) patients indicated differential methylation in genes associated with structural and nervous system development and neuron differentiation [72]."
"Although the immune system showed most changes in DNA methylation, we also found an enrichment in gene sets linked to cellular components, kinase activity, and positive metabolic activity, supporting previous data indicating differences in the expression of genes associated with cellular metabolism and oxidative stress in PBMCs from CFS patients [48,51,52]."
"The results of this study do not indicate whether these observed epigenetic differences are a cause or a consequence of CFS. However, we provide evidence suggesting a potential role for epigenetic alterations in the pathophysiology of CFS."
I would like to see the same study before and after excersise.