In fact, many studies have shown variable severity in FMF according to country of residence, irrespective of ethnicity and pathogenicity of MEFV variants.5 Ozen et al. showed in the large Eurofever registry of 346 FMF children that patients living in Eastern Mediterranean countries had more severe disease than those living in Western Europe, including Turkish children, suggesting that environmental factors affect FMF phenotypes. The gene discussed is MEFV; the disease is familial Mediterranean fever.