Department of Neurology, Columbia University, New York, New York 10032, USA.
Epilepsia. 2011 Nov;52(11):2076-83. doi: 10.1111/j.1528-1167.2011.03256.x. Epub 2011 Sep 11.
Mapping seizure susceptibility loci in mice provides a framework for identifying potentially novel candidate genes for human epilepsy. Using C57BL/6J × A/J chromosome substitution strains (CSS), we previously identified a locus on mouse chromosome 10 (Ch10) conferring susceptibility to pilocarpine, a muscarinic cholinergic agonist that models human temporal lobe epilepsy by inducing initial limbic seizures and status epilepticus (status), followed by hippocampal cell loss and delayed-onset chronic spontaneous limbic seizures. Herein we report further genetic mapping of pilocarpine quantitative trait loci (QTLs) on Ch10.
Seventy-nine Ch10 F(2) mice were used to map QTLs for duration of partial status epilepticus and the highest stage reached in response to pilocarpine. Based on those results we created interval-specific congenic lines to confirm and extend the results, using sequential rounds of breeding selectively by genotype to isolate segments of A/J Ch10 genome on a B6 background.
Analysis of Ch10 F(2) genotypes and seizure susceptibility phenotypes identified significant, overlapping QTLs for duration of partial status and severity of pilocarpine-induced seizures on distal Ch10. Interval-specific Ch10 congenics containing the susceptibility locus on distal Ch10 also demonstrated susceptibility to pilocarpine-induced seizures, confirming results from the F(2) mapping population and strongly supporting the presence of a QTL between rs13480781 (117.6 Mb) and rs13480832 (127.7 Mb).
QTL mapping can identify loci that make a quantitative contribution to a trait, and eventually identify the causative DNA-sequence polymorphisms. We have mapped a locus on mouse Ch10 for pilocarpine-induced limbic seizures. Novel candidate genes identified in mice can be investigated in functional studies and tested for their role in human epilepsy.
在小鼠中定位癫痫易感性基因座为鉴定人类癫痫的潜在新候选基因提供了框架。我们先前使用 C57BL/6J×A/J 染色体替换品系 (CSS) 发现，小鼠 10 号染色体 (Ch10) 上的一个基因座赋予了匹鲁卡品易感性，匹鲁卡品是一种毒蕈碱性乙酰胆碱激动剂，通过诱导初始边缘性癫痫发作和癫痫持续状态 (status)，随后海马细胞丢失和迟发性慢性自发性边缘性癫痫发作，模拟人类颞叶癫痫。在此，我们报告了 Ch10 上匹鲁卡品数量性状基因座 (QTL) 的进一步遗传定位。
使用 79 只 Ch10 F2 小鼠对部分癫痫持续状态持续时间和匹鲁卡品反应达到的最高阶段进行 QTL 定位。基于这些结果，我们创建了区间特异性同系物系，以通过基因型进行选择性连续繁殖来确认和扩展结果，将 A/J Ch10 基因组的片段分离到 B6 背景上。
Ch10 F2 基因型和癫痫易感性表型分析确定了在 Ch10 远端的部分癫痫持续时间和匹鲁卡品诱导癫痫严重程度的显著重叠 QTL。含有 Ch10 远端易感性基因座的区间特异性 Ch10 同系物也表现出对匹鲁卡品诱导的癫痫易感性，证实了 F2 作图群体的结果，并强烈支持在 rs13480781(117.6 Mb)和 rs13480832(127.7 Mb)之间存在一个 QTL。
QTL 定位可以识别对性状有定量贡献的基因座，并最终确定致病 DNA 序列多态性。我们已经在小鼠中定位了一个与匹鲁卡品诱导的边缘性癫痫发作相关的基因座。在小鼠中鉴定的新候选基因可以在功能研究中进行研究，并测试其在人类癫痫中的作用。
