Abstract
BACKGROUND: Chronic fatigue syndrome (CFS) is an illness with unknown aetiology and pathophysiology. The difference in incidence by sex observed for CFS indicates a role for oestrogen and oestrogen receptors in disease development. Furthermore, an immunomediated pathogenesis has been suggested for CFS, providing an additional connection to oestrogen, which displays immunomodular functions. AIMS: To investigate a possible association of oestrogen receptor (ER) mRNAs and two ERbeta single-nucleotide polymorphisms (SNPs) with CFS. METHODS: Messenger RNA levels of ERalpha, ERbeta wt and ERbeta cx were investigated in peripheral blood mononuclear cells from 30 patients with CFS and 36 healthy controls by quantitative real-time polymerase chain reaction. Two ERbeta SNPs were scored in the same material. RESULTS: The CFS group showed significantly lower mRNA expression levels of ERbeta wt compared with the healthy control group. No differences were observed for ERalpha or ERbeta cx between patients and controls. There were no significant differences in frequency for the investigated ERbeta SNPs between cases and controls. CONCLUSIONS: The reduced ERbeta wt expression level observed in this study is consistent with an immune-mediated pathogenesis of CFS. Additionally, the observation that ERbeta wt expression is decreased in CFS could provide an entry point to identify interesting, potentially disease-causing, candidate molecules for further study. A possible connection between oestrogen, oestrogen receptors and CFS should be evaluated further.