The objective of this study was to describe the first patient with recurrent ataxia and diplopia in association with a pathogenic variant in SCN8A.

We identified a girl with a heterozygous SCN8A pathogenic variant and performed thorough phenotyping.

A 10-year-old girl was previously well with normal intelligence. She had recurrent diplopia, dysmetria, and unsteady gait, which occurred only in the context of febrile illnesses. EEG during her initial acute episode showed multifocal epileptiform discharges, with similar findings seen on a follow-up study 3 months later when she was well. Brain MRI finding was normal. A gene panel identified a de novo SCN8A variant, p.Arg847Gln, classified as likely pathogenic. One year after her initial presentation, the girl is well and developmentally normal and has never had an event concerning for seizure.

This case presentation demonstrates that SCN8A pathogenic variants should be considered in children with transient ataxia, dysmetria, and diplopia in the context of viral febrile illnesses, even if there is no history of seizures. While there are clinical and molecular data suggesting that SCN8A dysfunction can cause temperature-sensitive phenotypes, further research is necessary to determine how the functional changes caused by our patient's SCN8A variant result in her unique phenotype.

本研究的目的是描述第一例与SCN8A致病性变异相关的复发性共济失调和复视患者。

我们鉴定出一名具有杂合SCN8A致病性变异的女孩，并进行了彻底的表型分析。

一名10岁女孩此前智力正常。她患有复发性复视、辨认困难和步态不稳，这些症状只发生在发热性疾病的情况下。在她最初的急性发作期间，脑电图显示多灶性癫痫样放电，3个月后她康复后的后续研究中也发现了类似的结果。脑部 MRI 检查结果正常。基因组鉴定出一种新的SCN8A变体 p.Arg847Gln，被归类为可能致病的。初次就诊一年后，女孩身体状况良好，发育正常，从未发生过与癫痫发作有关的事件。

本病例报告表明，对于病毒性发热性疾病背景下出现短暂性共济失调、辨距困难和复视的儿童，即使没有癫痫病史，也应考虑SCN8A致病性变异。虽然临床和分子数据表明 SCN8A 功能障碍可导致温度敏感表型，但仍需进一步研究以确定患者SCN8A变异引起的功能变化如何导致其独特的表型。