Background: Familial Mediterranean fever (FMF) is generally defined as an autosomal recessive disease, characterized by the automatic activation of the innate immune system in the absence of a detectable pathogenic stimulant. We hypothesize that the pathogenic factors, besides the genetic causes, may affect the development of FMF symptoms. To test this hypothesis, we examined the effects of human foamy virus (HFV) positivity on the occurrence of the clinical symptoms of FMF.
Materials and methods: Two hundred and twenty-two FMF patients with definitive diagnosis according to Tel Hashomer criteria (study group 1 [SG1]), 205 symptomatic FMF patients who had definitive diagnosis according to the same criteria but did not carry any of the 12 most commonly occurring MEFV gene mutations (study group 2 [SG2]), and 200 healthy individuals were included as control group (study group 3 [SG3]) in the study. The genetic analysis was applied in the Molecular Genetics Laboratory of the Department of Medical Biology, Faculty of Medicine, Ondokuz Mayıs University. This study was designed as a case-control study. HFV positivity was tested by amplifying the HFV bel1 gene sequence with polymerase chain reaction technique. Statistical analyses were conducted using SPSS version 23.0 software.
Results: HFV positivity showed significant differences between the study groups (P = 0.002). While 43 (19.02%) of the 222 SG1 patients were positive for the HFV bel1 gene sequence, 33 (16.09%) of the 205 SG2 patients were positive for the same sequence. Only 15 (7.5%) of the SG3 participants were positive for the presence of HFV bel1 gene sequence.
Conclusion: The results of our study suggested that HFV positivity can be a stimulant pathogenic factor of natural immune system which can cause the emergence of FMF symptoms.
Keywords: Bel1 gene; familial Mediterranean fever; human foamy viruses; inflammation; pyrin.