Pediatric Genomics Discovery Program, Department of Pediatrics, Yale University School of Medicine, New Haven, Connecticut, USA.
Division of Genetics and Metabolism, Phoenix Children's Hospital, Phoenix, Arizona, USA.
J Med Genet. 2019 Feb;56(2):113-122. doi: 10.1136/jmedgenet-2018-105322. Epub 2018 Oct 15.
Early infantile epileptic encephalopathies are severe disorders consisting of early-onset refractory seizures accompanied often by significant developmental delay. The increasing availability of next-generation sequencing has facilitated the recognition of single gene mutations as an underlying aetiology of some forms of early infantile epileptic encephalopathies.
This study was designed to identify candidate genes as a potential cause of early infantile epileptic encephalopathy, and then to provide genetic and functional evidence supporting patient variants as causative.
We used whole exome sequencing to identify candidate genes. To model the disease and assess the functional effects of patient variants on candidate protein function, we used in vivo CRISPR/Cas9-mediated genome editing and protein overexpression in frog tadpoles.
We identified novel de novo variants in () in two unrelated children with early infantile epileptic encephalopathy. Depleting with CRISPR/Cas9-mediated genome editing induced spontaneous seizures in tadpoles, mimicking the patients' condition. Overexpression of wild-type NEUROD2 induced ectopic neurons in tadpoles; however, patient variants were markedly less effective, suggesting that both variants are dysfunctional and likely pathogenic.
This study provides clinical and functional support for variants as a cause of early infantile epileptic encephalopathy, the first evidence of human disease caused by variants.
早发性婴儿癫痫性脑病是一种严重的疾病，包括早期起病的难治性癫痫发作，常伴有明显的发育迟缓。随着下一代测序技术的不断普及，人们已经能够识别出某些早发性婴儿癫痫性脑病的单一基因突变作为潜在病因。
本研究旨在鉴定候选基因作为早发性婴儿癫痫性脑病的潜在病因，并提供遗传和功能证据，支持患者变异是致病原因。
我们使用全外显子组测序来鉴定候选基因。为了模拟疾病并评估患者变异对候选蛋白功能的影响，我们使用体内 CRISPR/Cas9 介导的基因组编辑和蛋白过表达在青蛙蝌蚪中进行了研究。
我们在两名患有早发性婴儿癫痫性脑病的无关联儿童中发现了 （）中的新型新生变异。使用 CRISPR/Cas9 介导的基因组编辑敲除 会诱导蝌蚪自发性癫痫发作，模拟患者的情况。野生型 NEUROD2 的过表达会在蝌蚪中诱导异位神经元；然而，患者的变异体则明显效果较差，这表明这两种变异体都存在功能障碍，可能是致病原因。
本研究为 变异作为早发性婴儿癫痫性脑病的病因提供了临床和功能支持，这是首次证明人类疾病是由 变异引起的。
