Clinical characteristics of immunoglobulin A vasculitis associated with the Mediterranean fever gene mutation in Japanese patients: a case-based literature review

Background. Immunoglobulin A vasculitis (IgAV) is the most common vasculitis of childhood. However, its etiology remains unknown. In the Mediterranean region, 10% of patients with IgAV harbor homozygous and compound heterozygous mutations in the Mediterranean fever (MEFV) gene. Thus, such mutations may be involved in the development of IgAV. Objective. We present a Japanese patient with IgAV harboring MEFV gene mutation. Further, a comprehensive literature analysis was performed to validate the clinical characteristics of Japanese patients with IgAV harboring MEFV mutation. Methods. A 5-year-old girl presented with IgAV. She experienced prolonged abdominal pain, which was steroid-resistant. When treatment with colchicine was started, her abdominal pain disappeared immediately. The serum interleukin-18 levels of the patient and other patients with IgAV and FMF were evaluated using enzyme-linked immunosorbent assay. Moreover, all exons of the MEFV gene were analyzed using the direct sequence method. A comprehensive search of Japanese patients with IgAV harboring MEFV gene mutations in PubMed, Ichushi-Web, and Medical Online was conducted. Results. The serum interleukin-18 level of the patient was higher than that of other patients with IgAV and was similar to that of patients with FMF harboring M694I mutation. In addition, the patient presented with E148Q/M694I mutation. In previous studies, only four patients presented with IgAV harboring MEFV gene mutation in Japan. Conclusion. MEFV gene mutations can be masked if the symptoms of IgAV are prolonged or if patients are refractory to treatment. Moreover, the prevalence of IgAV associated with MEFV gene mutation is low in Japan.