Abstract:

Objective: Autoimmune cerebellar ataxia associated with anti-seizure related 6 homolog like 2 (SEZ6L2) antibody was reported, with the literature review and summary clinical features and treatment. Methods and Results: The patient was a 59-year-old female hospitaled in The First Affiliated Hospital of Zhengzhou University in July 2025, with progressive unsteady gait as the main clinical manifestation with dysarthria and mild cognitive dysfunction. Cell based assay (CBA) showed the titer of anti-SEZ6L2 antibody in serum was 1∶320, and cerebrospinal fluid was 1∶10. MRI showed cerebellar hemisphere and vermis mildly atrophy. The therapeutic effect of hormonotherapy was not good. After adding Efgartigimod α to eliminate pathogenic antibodies, the patient received sequential low-dose methylprednisolone therapy combined with mycophenolate mofetil for 3 months. The symptom was improved and could walk with unilateral assistance. Conclusions: Cerebellar ataxia was one of the clinical features of anti-SEZ6L2 antibody-associated disease, is associated with a poor prognosis. Efgartigimod α can be used as a treatment option to improve the prognosis of patients.

Key words: Autoimmune diseases, Cerebellar ataxia, Autoantibodies, Cerebrospinal fluid, SEZ6L2 (not in MeSH)

摘要：

目的: 报道1例抗癫痫相关蛋白6同源物2（SEZ6L2）抗体相关自身免疫性小脑性共济失调患者，复习相关文献，总结其临床特征及治疗方法。方法与结果: 郑州大学第一附属医院2025年7月收治1例59岁女性患者，以进行性行走不稳为主要表现，伴构音障碍、轻度认知障碍；细胞底物实验检测抗SEZ6L2抗体阳性，血清滴度为1∶320、脑脊液为1∶10；头部MRI显示小脑半球和蚓部轻度萎缩；激素治疗效果欠佳，加用艾加莫德α清除致病性抗体联合小剂量甲泼尼龙序贯和吗替麦考酚酯治疗3个月，症状改善，单侧辅助下可行走。结论: 小脑性共济失调是抗SEZ6L2抗体相关疾病的主要临床表现，预后欠佳，艾加莫德α可以作为一种治疗选择，改善患者预后。

关键词: 自身免疫疾病, 小脑共济失调, 自身抗体, 脑脊髓液, 癫痫相关蛋白6同源物2（非MeSH词）