台灣腦小血管病變之基因研究

Abstract

腦小血管疾病（CSVD）是最常見的慢性進行性血管疾病。此疾病導致約20-30%的中風，除了腦中風，腦小血管疾病也常以血管性失智症或血管性巴金森症等類神經退化性疾病為主要臨床表現。近年來，由於腦部影像檢查的進步及廣泛應用，腦小血管疾病在相關的臨床神經疾病扮演的角色愈發明確。 造成腦小血管疾病的病因有許多，常見的包括動脈硬化、類澱粉血管病變、發炎以及免疫有關的小血管病變。隨著基因診斷技術的快速發展，已鑑定出幾種由單基因變異引起的腦小血管疾病，如：自體顯性腦動脈血管病變合併皮質下腦梗塞及腦白質病變（CADASIL）、體隱性腦動脈血管病變合併皮質下腦梗塞及腦白質病變（CARASIL）、視網膜血管病變伴腦白質病變（RVCL）、COL4A1症候群、法布瑞氏症等，這五個疾病分別由不同基因變異所致病。 研究以次世代定序的技術分析臨床上懷疑為單基因變異引起腦小血管疾病的患者以及有腦出血症狀的患者，期望可以幫助這些患者找到致病原因，並了解本土基因變異分布的情形。本研究招募了133位懷疑為單基因變異引起腦小血管疾病的患者，以及432位有腦出血症狀的患者。實驗室根據文獻自行建立了CSVD panel，包含5個較常見與腦小血管疾病有關的基因：COL4A1, GLA, HTRA1, NOTCH3, TREX1。在133位懷疑為單基因變異引起腦小血管疾病的患者中我們找到了8個致病變異位點，檢出率約8%，以及11個意義尚未明確的變異位點。儘管目前對於CSVD 的病理和生理機制仍然不是很清楚。我們的研究探討了散發性的CSVD個案與CSVD有關之基因分布的情形，這將有助於幫助這類患者的診斷和治療。 相較於桑格定序，次世代定序是一個能大量平行定序，同時讀取上百萬條DNA序列的技術，可以在短時間內產出大量的數據，因此可以節省時間和花費。利用這項技術可以幫助患者找到造成腦小血管疾病的原因，此外，對台灣患者基因組成的了解擴大了我們對這種疾病的認識。

Cerebral Small Vessel Disease (CSVD) is a major cause of cerebrovascular diseases. It contributes to about 20-30% of strokes. Besides stroke, patients with CSVD often present as symptoms of vascular dementia or parkinsonism, mimicking primary neurodegenerative disorders. In recent years, the crucial role of CSVD in neurological disorders becomes clinically apparent with the significant progress and empirical application of advanced neuroimaging techniques. Causes of CSVD are various. Common causes of CSVD include arteriosclerosis, cerebral amyloid angiopathy (CAA), inflammation and immune-mediated small vessel diseases. Along with the rapid progress of genetic diagnostic techniques, several types of monogenic hereditary cerebral SVD have been identified: Cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL), cerebral autosomal recessive arteriopathy with subcortical infarcts and leukoencephalopathy (CARASIL), Retinal vasculopathy with cerebral leukodystrophy and Fabry disease. This project used next generation sequencing technology (NGS) to screen variants in patients with CSVD or Intracerebral hemorrhage (ICH) , expecting to find out causes, and understand the distribution of gene variants in local patients situation. We recruited 133 patients with CSVD and 432 patients with ICH. We used the self-designed NGS CSVD panel including 5 genes: COL4A1, GLA, HTRA1, NOTCH3, TREX1 to screen the DNA of the recruited patients. In this study, we sequenced 133 patients with CSVD and yielded approximately 8% diagnosis rate with identifying 8 different disease-causing variants and several variants of unknown significant (VUS). Although the pathophysiologic mechanisms of CSVD are not yet clear. Our study explored the status of multiple known monogenic CSVD genes in the sporadic population. This will help doctors identify what is causing patients symptoms and improves the quality of clinical decisions. Comparing with Sanger sequencing methods, next-generation sequencing (NGS) is a massively parallel sequencing technology. This process generates high throughputs with high resolution within several days. Using this technology can help patients find the cause of cerebral small vessel disease (CSVD). In addition, understanding of genetic composition of Taiwan patients expands our understanding of cerebral small vessel disease (CSVD).