對心搏過慢患者所做的基因分析

Genetic Analysis of Patients with Bradycardia

10.6342/NTU.2004.01286

薛嘉祥

心搏過慢 ； Bradycardia

臺灣大學藥理學研究所學位論文

2004年

碩士

賴凌平

繁體中文

背景 心搏過慢好發於高齡族群，它會造成疲倦、嗜睡、暈倒甚至瘁死。一般病態的心搏過慢可以分為病竇症候群及房室結傳導障礙兩種。到目前為止有釵h家族性的病竇症候群及房室結傳導障礙的病歷報告。而且在雙胞胎的研究中也同樣證明了對於竇房結的疾病（sinus node disease ,SND）以及心跳速率是有受到先天基因的調控的。 病患與方法 本實驗試著研究腎上腺乙型交感神經受體第一亞型（ADRB1 A231G）、內向整流鉀管道3.4（KCNJ5 C104T）、心臟奇趣電流管道（HCN2 C1239G）、膜電位依存性鈣離子管道3.2（CACNA1H G5207C）、心臟鈉電流管道（SCN5A A1673G、SCN5A C3266T）以及connexin40（CX40 A71G、CX40 G-44A）的單一核苷酸多型性與心搏過慢的關連性。其中SCN5A除了單一核苷酸多型性以外，我們也同時有進行突變的分析（SCN5A G4219A、SCN5A C3890T）。我們收集了264位平均年齡為72.5±12.7的心搏過慢的患者(病竇症候群179人，房室結傳導障礙85人)並以與病人一對一相對應的方式，配對相同性別、年齡而收集對照組。單一核苷酸多型性的鑑定方式則是採用聚合酶連鎖反應限制酶水解法來進行判別。除了判定單點單一核苷酸多型性與心搏過慢的關連性之外，我們也使用單套體分析（haplotype）以及多 因子多維減少分析(mdr ,multifactor-dimensionality reduction) (Ritchie MD et al.,2001)來同時分析多點的單一核苷酸多型性交互作用。 結果 在單點單一核苷酸多型性的分析中，我們發現在病人的族群中， SCN5A A1673G以及CX40G-44A的出現機會明顯小於正常人（p=0.034）。其他單一核苷酸多型性，包括ADRB1 A231G、HCN2 C1239G、KCNJ5 C104T、CACNA1H G5207C 、CX40 A71G以及SCN5A C3266T，在兩個族群的分佈上則沒有差異。而在CX40 G-44A與CX40 A71G所組成的四種單套體分析中，我們發現CX40 ( -44A,71A)以及CX40(-44G,71G)在病人以及對照組的分佈有顯著的差異(p值別為0.009, 0.003)。其中CX40 ( -44A,71A)較少見於病人(在病人與對照的出現頻率分別為0.033與0.073)， 而相對的CX40(-44G,71G)則較常見於病人(在病人與對照的出現頻率分別為0.081與0.035)。如果將病人分為病竇症候群與房室結傳導障礙兩組後再進行分析，我們發現CX40 ( -44A,71A)在房室結傳導障礙一組中可見到顯著的意義（p＝0.01），而CX40(-44G,71G)則是在病竇症候群一組中呈現出顯著的意義（p＝0.003）。在多因子多維減少分析中，我們發現這些單點SNP之間沒有明顯的交互作用。 結論 SCN5A A1673G基因型具有保護的作用而可以減少老年人嚴重心搏過慢的情況。而CX40 ( -44A,71A)以及CX40(-44G,71G)兩種單套體型式亦與心搏過慢有關。至於ADRB1 A231G、HCN2 C1239G、KCNJ5 C104T、SCN5A C3266T 、CACNA1H G5207C 則與心搏過慢無關。本研究顯示，心搏過慢的確具有遺傳的背景因素。

Background Cardiac bradyarrhythmia is commonly seen in elderly people. It causes symptoms of fatigue, dizzness, fainting, or even sudden death. Pathological bradycardia is usually caused by sick sinus syndrome and/or AV block. Familial sick sinus syndrome and AV block have been reported. Genetic influence on bradycardia has also been confirmed in twin studies. It is generally believed that there are some genetic factors contributing to the pathogenesis of bradyarrhythmias.. Patients and Methods In this report, we performed an association study to search for possible genetic factors causing bradycardias. We analyzed single nucleotide polymorphisms (SNPs) or mutations in ion channels genes and other genes using polymerase chain reaction (PCR) and restriction fragment length polymorphism(RFLP). These genes include beta 1 adrenergic receptor (ADRB1 A231G), funny current (HCN2 C1239G), inward rectifying potassium channel 3.4(KCNJ5 C104T), connexin 40 (Cx40 A71G, Cx40 G-44A) and cardiac sodium channel (SCN5A A1673G, SCN5A C3266T, SCN5A G4219A and SCN5A C3890T) and low voltage activated calcium channel 3.2 (CACNA1H G5207C) . We enrolled 264 patients with an average age of 72.5±12.7 years and the control group was matched to the cases regarding to age and gender one by one. Results We found that the allele frequency of SCN5A A1673G and CX 40G-44A was significantly lower in cases than in controls (p = 0.034, 0.046 respectively) while other SNPs (including ADRB1 A231G, HCN2 C1239G, KCNJ5 C104T, Cx40 A71G, and SCN5A C3266T) did not show significant difference between cases and controls. In haplotype analysis for Cx40, we found the incidence of CX40(-44A,71A) was significantly lower in cases while the incidence of CX40(-44G,71G) was significantly higher in cases( p=0.009 and 0.003 respectively). In subgroup comparison, we found that the incidence of CX40 ( -44A,71A) was significantly lower in patients with AV block（p＝0.01）, while the incidence of CX40(-44G,71G) was significantly higher in patients with sick sinus syndrome（p＝0.003）. MDR analysis showed that there was no significant gene interactions among the SNPs. Conclusion SCN5A A1673G allele was protective against the occurrence of bradycardia. CX40(-44A,71A) and CX40(-44G,71G) was associatiated with AV block and sick sinus syndrome respectively. For CX40 gene, the incidence of (-44A,71A) haplotype was significant lower in cases while the incidence of (-44G,71G) haplotype was significant higher in cases. There was no association between bradycardia and ADRB1 A231G, HCN2 C1239G, KCNJ5 C104T, SCN5A C3266T. Our investigation demonstrated possible genetic factors contributing to the pathogenesis of bradyarrhythmia.