Clinical subsets of juvenile dermatomyositis classified by myositis-specific autoantibodies: Experience at a single center in Japan

Abstract

Similar to findings in Western countries, the clinical characteristics of JDM in Japanese may differ for each type of MSAs.

Autoantibodies in Juvenile Dermatomyositis: Need to Bridge the Bench and Bedside Gap

“…These observations are in stark contrast to a large cohort from the UK reporting 59% (225/380) antibody positivity, and 50% of this cohort had MSAs [1]. The findings of the Indian cohort are also different from a Japanese study wherein 95.2% (20/21) were positive for MSAs [4]. In both UK and Japanese cohorts, anti-TIF-ϒ was the most common antibody, whereas none in the Sharma et al study had anti-TIF-ϒ antibody [3].…”

Clinical practice guidance for juvenile dermatomyositis (JDM) 2018-Update

“…In the US and European cohorts, autoantibodies are identified in about 70% of patients with JDM, and many of them showed positive response for anti-transcriptional intermediary factor-1Ç (TIF-1Ç) or anti-MJ/ nuclear matrix protein (NXP) 2 antibodies [4,5,23]. After the Japanese version of the guidance had been published, two Japanese groups have reported the frequency of MSAs [6,35]. Both reports show higher frequencies of anti-MDA5 antibodies (20-30%) than those in the UK registry (7.4%) [4].…”

“…Although the incidence of ILD in JDM is not clear, a nationwide survey in Japan reported 13 deaths with JDM in 5 years, six of which were attributed to RP-ILD [121]. Anti-MDA5 autoantibodies are positive in one-third of Japanese patients with JDM in Japan (seen more frequently than in Western countries) and related to both DM-and JDM-associated ILD [4][5][6]30,[35][36][37][38][39]122,123]. Particularly high titers of the autoantibody are associated with RP-ILD in children [30,36].…”

“…Particularly high titers of the autoantibody are associated with RP-ILD in children [30,36]. On the other hand, anti-ARS antibodies which are related to chronic and recurrent ILD in adult DM are quite rare in children [4][5][6]35].…”

Understanding and managing anti-MDA 5 dermatomyositis, including potential COVID-19 mimicry

“…An increased association of ILD was seen with coexistent anti-Ro52 antibodies (70% vs 10% had ILD among patients with anti-MDA5 JDM) in an American cohort of JDM but RP ILD was uncommon [61]. Whereas, in East Asian cohorts over 1/3rd of JDM are constituted by anti-MDA5 DM with RP ILD seen in over half of them [7,62,63]. There were few anti-MDA5-positive JDM subjects in the Indian cohorts described, though the phenotype was akin to that described in the western literature [64].…”