We identified a novel nonsense de novo pathogenic variant of the NEXMIF gene in a 29 year‐old female patient with refractory epilepsy and mild intellectual disability. The patient presented with episodic atypical absence status (AS), the longest duration of her seizures was approximately 36 hr. She also had occasional eyelid myoclonia during absence seizure. EEG highlighted a photosensitivity phenomenon and generalized epileptiform discharges that were induced by eye closure. Whole exome sequencing revealed a novel nonsense pathogenic variant c.1063delC (p.L355*) in exon 3 of the NEXMIF gene. The mRNA expression of NEXMIF in this female patient was below −2 SD from the mean of control group. In addition to adding a novel pathogenic variant type to the NEXMIF variant database and conducting mRNA studies, this report also describes a unique phenotype in a patient with atypical AS associated with a NEXMIF variant. We discuss implications for medication management in similar patients.

中文翻译：

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女性难治性癫痫和智力残疾的新型NEXMIF基因致病变异。

我们在一名顽固性癫痫和轻度智力障碍的29岁女性患者中鉴定出NEXMIF基因的新型无意义的致病性变体。该患者表现为发作性非典型性失神状态（AS），其发作的最长持续时间约为36小时。在失神发作期间，她还偶有眼睑肌阵挛。脑电图突出显示了光敏性现象和闭眼引起的广泛性癫痫样放电。整个外显子组测序揭示了NEXMIF基因第3外显子中新的无意义的致病变异体c.1063delC（p.L355 *）。该女性患者中NEXMIF的mRNA表达低于-2 SD从对照组的平均值。除了向NEXMIF变异数据库添加新的致病变异类型并进行mRNA研究外，该报告还描述了非典型AS与NEXMIF变异相关的患者的独特表型。我们讨论了类似患者中药物治疗的意义。