Anti-seizure related 6 homolog like 2 antibody-associated encephalitis: two cases report and literature review

doi:10.3969/j.issn.1672-6731.2025.12.008

Abstract

Abstract: Objective To report and analyze clinical features of anti-seizure related 6 homolog like 2 (SEZ6L2) antibody-associated encephalitis, and review relevant literatures. Methods and Results Two patients were all diagnosed and treated by Ruijin Hospital, Shanghai Jiaotong University School of Medicine from January 2022 to July 2024. The clinical manifestations were mainly with ataxia, gait abnormalities, cognitive dysfunction and bradykinesia. One case exhibited dysautonomia. Cerebrospinal fluid (CSF) white cell counts were elevated, and both serum and CSF antibodies related to autoimmune encephalitis were negative. Further testing for anti-SEZ6L2 antibody revealed that CSF and (or) serum were positive. MRI showed cerebellar atrophy, while ¹⁸F-DPA714 PET/MRI indicated abnormal increased uptake in the cerebellum. ¹⁸F-FDG PET did not reveal any malignant tumors, however, one case showed decreased metabolism in the cerebellum, frontal lobe and temporal lobe. The clinical diagnosis was anti-SEZ6L2 antibody-associated encephalitis, and after immunotherapy, the symptoms improved. Conclusions Anti-SEZ6L2 antibody-associated encephalitis is rare, and it has complicated clinical manifestations. There are difficulties in the early diagnosis and differential diagnosis, but early immunomodulatory treatment leads to a good prognosis in some patients.

Key words: Encephalitis, Autoimmune diseases, Autoantibodies, SEZ6L2(not in MeSH)

摘要： 目的报告2例抗癫痫相关蛋白6同源物2（SEZ6L2）抗体相关脑炎病例，通过复习相关文献，总结抗SEZ6L2抗体相关脑炎临床特征。方法与结果 纳入2022年1月至2024年7月上海交通大学医学院附属瑞金医院诊断与治疗的2例抗SEZ6L2抗体相关脑炎患者。2例患者临床主要表现为共济失调、步态异常、认知功能障碍、运动迟缓，其中1例存在自主神经功能障碍；脑脊液白细胞计数增加，血清和脑脊液自身免疫性脑炎相关抗体阴性，进一步检测抗SEZ6L2抗体，血清和（或）脑脊液均阳性；头部MRI显示小脑萎缩，¹⁸F-DPA714 PET/MRI显示小脑摄取异常增高，提示神经炎症；¹⁸F-FDG PET未见恶性肿瘤，其中1例显示小脑、额叶和颞叶代谢降低。临床诊断为抗SEZ6L2抗体相关脑炎，经免疫治疗后症状好转。结论抗SEZ6L2抗体相关脑炎罕见，临床表现复杂多样，早期诊断与鉴别诊断困难，早期予免疫调节治疗对预后至关重要。

关键词: 脑炎, 自身免疫疾病, 自身抗体, 癫痫相关蛋白6同源物2（非MeSH词）

CHENG Na, LU Yi-zhou, CHEN Sheng, ZHOU Qin-ming. Anti-seizure related 6 homolog like 2 antibody-associated encephalitis: two cases report and literature review[J]. Chinese Journal of Contemporary Neurology and Neurosurgery, 2025, 25(12): 1150-1156.

程娜, 卢逸舟, 陈晟, 周勤明. 抗癫痫相关蛋白6同源物2抗体相关脑炎两例并文献复习[J]. 中国现代神经疾病杂志, 2025, 25(12): 1150-1156.

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