Myotonic dystrophies (DMs) are autosomal dominant disorders with multisystemic clinical features. DMs are categorized as DM1, caused by a (CTG)n expansion mutation in 19q13, and DM2, caused by a (CCTG)n expansion mutation in 3q21. Clinical feature of DM2 are diffuse and proximal dominant weakness, wasting, myotonia, cardiac problems, cataracts, insulin-resistance. DM2 is considered to milder form than DM1. Here We compared clinical feature in both DMs. We identified a Japanese patient with DM2 and showed clinical features same as a past report. But DM2 is clinically variable, further investigation of Japanese patients is needed in order to confirm these findings in Japan.