Xu Qin, Jin Xuexiao, Jiang Yu, Dang Xin, Han Yongmei
Department of Rheumatology in Sir Run Run Shaw Hospital, Zhejiang University School of Medicine, Hangzhou, 310016, People's Republic of China.
Institute of Immunology, Zhejiang University School of Medicine, Hangzhou, 310058, People's Republic of China.
Clin Rheumatol. 2021 Mar;40(3):1147-1157. doi: 10.1007/s10067-020-05286-y. Epub 2020 Jul 16.
The JAK family (JAK1, JAK2, JAK3, and TYK2) have recently emerged as a potential therapeutic management in controlling severe and refractory dermatomyositis. Meanwhile, the progress in the discovery of JAK blockers is significant, with an increasing number of selective JAK inhibitors reported and some are in or prepare for clinical trials. However, the importance of each JAK in dermatomyositis is unclear, which is critical for a comprehensive understanding of dermatomyositis and significant for forming mechanism-based strategy. Here, we presented a case with clinically amyopathic dermatomyositis and essential thrombocytosis with a somatic constitutive active mutation of JAK2(V617F). The coexistence of these two uncommon diseases attracted us to investigate their underlying relationship. To this end, we characterized the clinical course and laboratory findings of this patient. Particularly, we correlated JAK2(V617F) mutation burden in affected peripheral blood subset with clinical activity score of dermatomyositis. Based on our observation, we concluded that these two diseases are independent disorders, and JAK2(V617F) mutation burden is irrelevant to the severity of dermatomyositis. Finally, we reviewed the literature and summarized them with a thorough discussion.
JAK家族（JAK1、JAK2、JAK3和TYK2）最近已成为控制重症和难治性皮肌炎的一种潜在治疗手段。与此同时，JAK阻滞剂的发现取得了重大进展，有越来越多的选择性JAK抑制剂被报道，其中一些已进入或准备进入临床试验阶段。然而，每种JAK在皮肌炎中的重要性尚不清楚，这对于全面了解皮肌炎至关重要，对制定基于机制的策略也具有重要意义。在此，我们报告了一例临床无肌病性皮肌炎合并原发性血小板增多症且存在JAK2体细胞组成性激活突变（V617F）的病例。这两种罕见疾病的共存促使我们去探究它们之间的潜在关系。为此，我们对该患者的临床病程和实验室检查结果进行了描述。特别地，我们将受累外周血亚群中的JAK2（V617F）突变负荷与皮肌炎的临床活动评分进行了关联分析。基于我们的观察，我们得出结论，这两种疾病是独立的病症，且JAK2（V617F）突变负荷与皮肌炎的严重程度无关。最后，我们查阅了文献并进行了全面讨论后对其进行了总结。
