IgA Vasculitis in Japanese Patients Harboring MEFV Mutations: A Case Report and Review of the Literature.

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 () gene. Thus, such mutations may be involved in the development of IgAV. Herein, we present a five-year-old girl presented with IgAV. She experienced prolonged abdominal pain, which was steroid-resistant. When treatment with colchicine was started, her abdominal pain resolved immediately. The serum interleukin (IL)-18 levels of the patient and other patients with IgAV and familial Mediterranean fever (FMF) were evaluated using enzyme-linked immunosorbent assay. The serum IL-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. Moreover, all exons of the  gene were analyzed using the Sanger sequencing and the patient presented with E148Q/M694I mutation. Further, a comprehensive search of Japanese patients with IgAV harboring  gene mutations in PubMed, Ichushi-Web, and Medical Online was conducted to validate the clinical characteristics of Japanese patients with IgAV harboring  gene mutation. In previous studies, only five patients presented with IgAV harboring  gene mutation in Japan.  The prevalence of IgAV associated with  gene mutation may be low in Japan. However, gene mutations should be suspected if the symptoms of IgAV are prolonged or if patients are refractory to treatment. In such case, IL-18 monitoring and colchicine treatment may be useful for IgAV with  gene mutation.