Are fibromyalgia and chronic fatigue syndrome different illnesses or simply different manifestations of the same disorder? Researchers and physicians have debated this question for years. A new study from Spain, to be presented at the Annual European Congress of Rheumatology in Barcelona in mid-June, may have taken a big step toward answering that question once and for all.
In this study, scientists looked at the variation in Single Nucleotide Polymorphisms (SNPs) of different etiopathogenic pathways in order to gain insights into the genetic profile of FM and CFS. They also related the severity of both diseases to the variation of SNPs.
Objectives: The study was conducted to test the hypotheses that FM and CFS are different clinical and genetic entities and that the phenotypic variation observed in both diseases is part of the result of a different genetic profile.
Methods: The American College of Rheumatology’s 1990 diagnostic criteria for fibromyalgia and the Center for Disease Control’s 1994 Fukuda diagnostic criteria for chronic fatigue syndrome were used for the respective diagnosis of FM and CFS. Participants included a group of 403 women (186 with FM, 217 with CFS) and an independent validation group of 282 women (126 with FM, 156 with CFS), The Fibromyalgia Impact Questionnaire and the CDC Symptom Inventory Questionnaire were used to define severity subgroups.
Results: Fifteen SNPs were identified and used to discriminate between FM and CFS patients with an 11.5 Likelihood Ratio (LR+, 95% specificity). The analysis of further SNPs allowed differential genetic profiling between the most aggressive FM phenotype and the mild forms as well as between a severe CFS phenotype and a milder one (both 12.4, LR+).
Conclusion: The models described in this study are suitable for the differential diagnosis between FM and CFS, as well as to differentiate subtypes between severe and milder phenotypes of both diseases, in a female Spanish population. These subtypes could represent different illnesses or clinical situations that, in the future, can be differentiated.
Published On: May 31, 2007