MEFV mutations in systemic onset juvenile idiopathic arthritis
Autoinflammatory diseases constitute a large spectrum of monogenic diseases like FMF or cryopyrin-associated periodic syndromes (CAPS) and complex genetic trait diseases such as systemic onset juvenile idiopathic arthritis (SoJIA). An increased rate of MEFV mutations has been shown among patients with PAN and HSP, in populations where FMF is frequent. The aim of the study is to search for MEFV mutations in our patients with SoJIA and see whether these mutations had an effect on disease course or complications. Thirty-five children with the diagnosis of SoJIA were screened for 12 MEFV mutations. The control data were obtained from a previous study of our centre determining the carrier frequency in Turkish population. Two patients were homozygous and three patients were heterozygous for the M694V mutation. One patient was a compound heterozygote for the M680I/V726A mutations. Heterozygous V726A mutation was found in one patient. The overall mutation frequency of patients was 14.28%. This figure had been compared with the previously published rate of disease-causing mutations in this country, which is 5%. Disease-causing mutations were found to be significantly more frequent in the SoJIA patients than the population (P < 0.01). Among these, M694V was the leading mutation with a frequency of 10% in SoJIA. Six patients carrying MEFV mutations were among the most resistant cases requiring biological therapy. SoJIA patients had a significantly higher frequency of MEFV mutations but clinical studies with large number of patients are needed to confirm the association of MEFV mutations with SoJIA and its course.