Methylation problems such as MTHFR is always associated with fibromyalgia: at least all the cases I’ve seen. I think methylation problems, along with their vitamin deficiencies they cause, are the cause for the fatigue and CFS (chronic fatigue syndrome) commonly found in fibromyalgia. This proves my point. (So if you have fibro or IC, get your metHylation and mitochondrial errors defined with my FOUNDATION METHYLATION GENETIC PANEL off my website under testing at www.danpursermd.com )

https://pubmed.ncbi.nlm.nih.gov/25824380/