Periodic fever, aphthous stomatitis, pharyngitis and adenitis (PFAPA) syndrome is an autoinflammatory disease and the most common periodic fever syndrome in the paediatric population. PFAPA, which shares certain similarities with monogenic fever syndromes, is currently etiologically unexplained. Clinically similar periodic fever syndromes are of genetic nature, which together with the fact that PFAPA clusters in some families, suggests a possible genetic predisposition of the PFAPA syndrome. Published data show that PFAPA is most likely caused by a combination of several genetic and environmental factors. The syndrome is characterized by spontaneous resolution, suggesting that the mechanism which maintains or triggers the disease is transient in nature. The suspicion that PFAPA syndrome is caused by a genetic mechanism and that the mechanism of the disease is likely to be transient, both point in the direction of DNA methylation as a possible pathogenetic mechanism. We compared DNA methylation profiles between patients with PFAPA syndrome and healthy children at the genome level, using enrichment methods MeDIP and MBD. The study showed that there are changes in DNA methylation patterns in children with PFAPA syndrome compared to healthy children. We identified 24 genomic regions that were hyper- or hypomethylated in patients as compared to healthy children of similar age, however, there was no statistically significant enrichment of a particular biological process or molecular function. Regions were annotated to the genes involved in inflammatory and immune cell differentiation processes, but not with the genes associated with the development of monogenic autoinflammatory diseases. We successfully confirmed the results with MSRE-qPCR. Although the impact of altered DNA methylation in patients with PFAPA syndrome remains unclear, our study suggests that the syndrome could be caused by altered methylation patterns, probably caused by environmental influences such as infection. The identified differences between patients with PFAPA syndrome and healthy children point to a possible new role of DNA methylation in the development of PFAPA syndrome as well as other complex and unexplained immune diseases.
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