Familiar Mediterranean fever (FMF) is a well defined autosomal recessive disease occurring mostly in Mediterranean regions. Here we present the experience from one center from Czech Republic, where we follow 4 families with patients with genetically proven FMF. Three out of these 4 families cluster to one limited region in Moravia, in the heart of Europe, without any linkage to Mediterranean origin. Furthermore, majority of these patients are heterozygots presenting with well defined typical clinical symptoms. Potential pseudodominant inheritance and/or epigenetic and environmental factors might influence clinical presentation of the disease.