Fibromyalgia Driven by Two Viruses and the Risk Genes: Epstein-Barr Virus Explains the Female Bias and Herpes Simplex Virus Type 1 Causes the Pain

Abstract

Fibromyalgia affects 2-4% of the population with a female predominance of up to 9:1, yet its etiology has remained unknown. Here we integrate the largest fibromyalgia genome-wide association study (GWAS) to date (Nature Medicine 2026, 2.5 million individuals, 26 loci) with published transcriptomic, virological, and pharmacological evidence to propose a mechanistic model. The GWAS identifies risk loci near GPR52, DRD2, NPC1, PPP2R2B, and HTT. Four of these genes (GPR52, DRD2, NPC1, PPP2R2B) regulate HSV-1 reactivation through distinct but converging pathways, while HTT acts through autophagy. GPR52 and DRD2 both control intracellular cAMP, which activates protein kinase A (PKA); cAMP/PKA signaling has been proposed to promote HSV-1 reactivation, although the putative cAMP-response element in the ICP0 promoter is non-functional. NPC1 controls cholesterol trafficking potentially required for HSV-1 replication. PPP2R2B encodes a subunit of PP2A, a family that restricts HSV-1. The GWAS also identifies MAML3, a Notch coactivator that binds RBP-Jk, the transcription factor hijacked by EBNA2. Analysis of RBP-Jk ChIP-seq data (GSE75503) reveals that EBNA2 binds TLR7/TLR8 but not KDM6A/DDX3X on the X chromosome. The female bias arises from constitutive X-Y divergence (not EBV-driven). B cells carrying EBV may infiltrate the dorsal root ganglia (DRG), where KDM6A removes the repressive H3K27me3 mark from the latent HSV-1 genome, de-repressing it, and genetically elevated cAMP triggers reactivation via ICP0. Reactivated HSV-1 damages satellite glial cells, which induce DRG neurons to release Substance P and stress neuropeptides that activate mast cells through MRGPRX2; anti-glial IgG arises as a collateral marker of this damage. The model predicts that lowering cAMP with bromocriptine or propranolol should reduce HSV-1 reactivation and pain. Both drugs are generic, safe, and under independent clinical investigation.