@article{oai:nagasaki-u.repo.nii.ac.jp:00001460, author = {Endo, Yushiro and Koga, Tomohiro and Ishida, Midori and Fujita, Yuya and Tsuji, Sosuke and Takatani, Ayuko and Shimizu, Toshimasa and Sumiyoshi, Remi and Igawa, Takashi and Umeda, Masataka and Fukui, Shoichi and Nishino, Ayako and Kawashiri, Shin-ya and Iwamoto, Naoki and Ichinose, Kunihiro and Tamai, Mami and Nakamura, Hideki and Origuchi, Tomoki and Agematsu, Kazunaga and Yachie, Akihiro and Masumoto, Junya and Migita, Kiyoshi and Kawakami, Atsushi}, issue = {1}, journal = {Arthritis Research & Therapy}, month = {Nov}, note = {BACKGROUND: We showed previously that Japanese individuals with familial Mediterranean fever (FMF) have a more atypical phenotype compared to endemic areas. The clinical differences between young-onset FMF (YOFMF), adult-onset FMF(AOFMF), and late-onset FMF(LOFMF)in Japan are unclear. METHODS: We enrolled 395 consecutive patients. We defined YOFMF, AOFMF, and LOFMF as the onset of FMF at<20, 20-39, and??40years of age, respectively. We compared clinical manifestations and MEFV mutations patterns among these groups. RESULTS: Median ages at onset were YOFMF 12.5 years (n?=?182), AOFMF 28 years (n?=?115), and LOFMF 51years (n?=?90). A family history, MEFV mutations in exon 10, and more than two MEFV mutations were significantly more frequent in the earlier-onset groups (p?