Transcriptome analysis in rTOF patients determined the RVOT myocardium gene expression and revealed the genetic features of RV dysfunction progression

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart defect. From the genetic perspective, the etiology of TOF is multifactorial. Despite successful surgical repair, many patients have chronic volume and pressure loading leading to a 40% probability of right ventricular (RV) failure by the 3rd decade of life. In addition, some patients developed RV failure before 30 years of age. Heart failure in repaired TOF (rTOF) is recognized as a significant complication. Its occurrence is strongly associated with adverse outcome. Although pulmonary valve replacement (PVR) can delay and improve RV failure, the optimal timing of PVR is still unknown because of the unnatural history of rTOF. Therefore, it is necessary to better understand the molecular and cellular mechanisms which lead to progressive RV enlargement and dysfunction in rTOF patients.Messenger RNA (mRNA) are coding RNA is a single-stranded nucleotides that carries genetic information to guide protein synthesis which are transcripted from one strand of DNA. Messenger RNA accounts for only 2%-5% of the total RNA of human cells, but it widest in variety and most active in metabolism. Based on its rapid expression, simple sequence composition, low immunogenicity and flexible modification, great progress has been made in mRNA therapy which has been used in the treatment of rare genetic metabolic diseases. The research on mRNA therapy for heart disease is in progress, so mining the mRNA profile of RV in rTOF patients is helpful to find potential therapeutic targets and provide necessary theoretical basis of mRNA therapy for RV dysfunction in rTOF patients.We hypothesized that mRNA profiles in RV cardiomyocyte would provide insight into the mechanism of disease progression which could then aid in risk stratification and early prediction of RV failure in rTOF patients. For this purpose, we used RNA-seq to analyze the data pertaining to expression levels and performed high-resolution transcriptome analyses of the myocardial tissue of RV. The RNA-seq library was sequenced using the DNBSEQ platform, which uses the DNA nanoball technology.

法洛四联症（Tetralogy of Fallot, TOF）是最常见的发绀型先天性心脏缺损。从遗传学视角来看，TOF的病因呈多因素特征。尽管手术修复已可取得成功，但诸多患者仍会出现慢性容量与压力负荷过载，至人生第三十年时，右心室（right ventricular, RV）衰竭的发生概率高达40%；部分患者甚至在30岁前就已出现右心室衰竭。修复术后法洛四联症（repaired TOF, rTOF）患者合并心力衰竭已被认定为严重并发症，其发生与不良预后显著相关。尽管肺动脉瓣置换术（pulmonary valve replacement, PVR）可延缓并改善右心室衰竭，但由于rTOF患者的病程具有非自然性，肺动脉瓣置换术的最佳时机仍未明确。因此，亟需进一步阐明rTOF患者中进行性右心室扩大与功能异常的分子及细胞机制。

信使RNA（Messenger RNA, mRNA）为编码型RNA，属于单链核苷酸分子，可携带遗传信息以指导蛋白质合成，由DNA单链转录生成。在人类细胞的总RNA中，信使RNA仅占2%~5%，但其种类最为丰富、代谢活性最强。依托其表达快速、序列组成简洁、免疫原性低且可灵活修饰的特性，mRNA治疗已取得重大进展，并已应用于罕见遗传性代谢疾病的治疗。当前针对心脏疾病的mRNA治疗研究仍在推进中，因此解析rTOF患者右心室的mRNA表达谱，有助于发掘潜在治疗靶点，为rTOF患者右心室功能异常的mRNA治疗提供必要的理论基础。

我们提出假说：右心室心肌细胞的mRNA表达谱可揭示疾病进展的核心机制，进而辅助rTOF患者的危险分层及右心室衰竭的早期预测。为此，我们采用RNA测序（RNA-seq）技术分析相关表达水平数据，并对右心室心肌组织开展高分辨率转录组分析。本次RNA测序文库采用DNBSEQ平台完成测序，该平台依托DNA纳米球技术实现测序。