Familial mediterranean fever - An increasingly important childhood disease in Sweden

Aim To characterize Familial Mediterranean Fever (FMF) in western Sweden, focusing on genotype, clinical picture, prevalence and age of onset as well as time to diagnosis. Methods Patients with autoinflammatory diseases are continuously registered at the five main hospitals in Western Sweden. Case records of patients with FMF were analysed retrospectively. Population data on immigration was retrieved from Statistics Sweden. Results Until 2008, 37 patients with FMF were identified. The prevalence among inhabitants of Turkish, Lebanese, Syrian and Iranian origin was 173, 124, 86 and 17/100 000, respectively. Median age at first symptoms was 4 years (range 3 month-37 years) and at diagnosis 10 years (range 2-44 years). Median time from first symptoms to diagnosis was 4 years (range <1 year-34 years). Among 32 patients screened for twelve common mutations, 75% were homozygotes or compound heterozygotes, 16% were heterozygotes and in 9% no mutation was found. In our cohort the frequencies of symptoms were fever 100%, peritonitis 92%, pleuritis 22% and arthritis 11%. Conclusions The majority of patients with FMF present during childhood. The prevalence among immigrants in western Sweden is in the same range as in their country of origin. Time to diagnosis needs to be shortened by means of increased awareness of the disease.