| Abstract: | 癲癇佔總人口 1%，而兒童比成人多，而兒童有一部分為不明原因癲癇(idiopathic epilepsy)，其定義為癲癇且無明顯腦部病變與之相關，KCNQ2突變可造成如此。KCNQ2 為細胞膜鉀離子通道調控基因。對帶有 KCNQ2突變的人，部份會有癲癇與智障，但目前 尚未完全瞭解。而我目前初步研究結果，發現兒童不明原因癲癇帶 KCNQ2基因突變約 1/3，但不知這些突變是否有相關性。因此本研究的目的要利用次世代基因定序方法 (next generation sequence) 建立台灣地區不明原因癲癇 KCNQ2基因突變的盛行率資 料庫，更進一步的利用細胞模式探討 KCNQ2基因突變後所造成的功能影響，來釐清 KCNQ2 基因在兒童不明原因癲癇所扮演的角色和致病機轉。在計畫中我們分兩部分進行：第一 部分，我們已完成 50 個正常人和 30個病人的 KCNQ2基因篩檢，為建立更完整的資料庫。 接下來，我們將再進行另外 70個 (共 100個病人)有不明原因癲癇兒童病人的檢查。第 二部份，將依據我們在病童中所發現 KCNQ2的突變進行功能分析，首先我們將利用分 子生物學技術選殖出 KCNQ2全長基因和建構含 KCNQ2基因突變的表現載體，再利用 微脂粒基因轉殖方法將 KCNQ2突變的基因轉殖入(transfection) 爪蟾卵母細胞中，並利 用電生理的技術來探討 KCNQ2基因突變的電生理功能的差異。相信本計畫如獲得支持 對於釐清 KCNQ2基因在兒童不明原因癲癇的致病機轉有很大的助益。
Background and Objectives： Idiopathic epilepsy usually has genetic heterogenicity. The common genetic cause for idiopathic epilepsy including KCNQ2 mutation, in which, has been known the phenotype of neonatal seizure during first week, however, other presentations including febrile seizure, benign childhood epilepsy with centrotemopral spikes, childhood absence seizure, idiopathic photosensitive convulsion were also reported. The mutant gene locates at 20q13, a voltage-gated potassium channel gene. Until recently, KCNQ2 encephalopathy with mental retardation and refractory seizures have been reported as a new phenotype. The new antiepileptic drug, retigabine, works primarily as a potassium channel opener by activating a voltage-gated potassium channels in the brain. It highlights KCNQ2 encoding childhood epilepsy plays an important role in the pathogenesis and management of epilepsy, however, unfortunately, still not well known. We have studied KCNQ2 genotype from 30 patients and 50 normal controls. The mutation, c. 912 C>C/T (E304E) were detected in 40 % from normal control group. KCNQ2 mutations were detected in 30% from 30 patients with idiopathic childhood epilepsy. From those patients, KCNQ2 mutation variants included c. 1545 G>G/C (E515D); c. 2235 G>G/A (P745P); c. 2339 A>C (N780T); c.1914C>T (P638L); 1627G>A ((V543M); 2338A>C ((T780P), in which, not found in the normal control. Based on the findings, we will further do functional study for the mutation variants. Patients and methods： 1. We will do KCNQ2 sequence for other 70 (total 100) childhood patients with idiopathic epilepsy, and to investigate whether this mutation is associated with epilepsy after comparing those mutation variants between patients and control group. 2. We will use Xenopus oocytes model for functional study of KCNQ2 mutation variants including: c. 1545 G>G/C (E515D); c. 912 C>C/T (E304E); c. 2235 G>G/A (P745P); c. 2339 A>C (N780T); c.1914C>T (P638L); 1627G>A (V543M); 2338A>C ((T780P), which have been found in the past result and further mutations from 70 patients in the study . We will recombine plasmid of pTLN-KCNQ2 and pLEGFP-KCNQ2, and knock in Xenopus oocyte to investigate the electrical change of cell membrane by two-electrode voltage-clamp and whole-cell patch recording. In Taiwan, to our best knowledge, the association of epilepsy and KCNQ2 has not been done. The study will help us understand the role of KCNQ2 mutation in idiopathic epilepsy and set up the animal model for investigate the KCNQ2 encoding epilepsy. |
