人类珠蛋白相关基因上游开放阅读框的变异分析

β-地中海贫血症是一种珠蛋白生成障碍的常染色体隐性遗传病。而γ珠蛋白基因的开放表达和胎儿血红蛋白的合成,是缓解β地中海贫血病人临床表型的一个重要因素。本研究针对202个血红蛋白相关调控基因或miRNA,对1802个β-地中海贫血症患者进行了目标区域捕获测序。通过生物信息学的分析,检测出了所有捕获区域内的突变。进一步对位于5′端非编码区(5′untranslated region, 5′UTR)的突变进行系统扫描,共计寻找到41个影响uORF(upstream open reading frame, uORF)有或无的功能性突变。从中选取了CHTOP基因(chr1:153606541 C>T)和TGFB1基因(chr19:41859418 G>A)的两个突变,通过定点诱变和双荧光素酶报告实验,在体外证实这两个突变均可显著地改变下游基因的表达。该研究结果为β-地中海贫血症临床表型的精确诊断提供了潜在的筛查靶点。

Analysis of variants in upstream open reading frames of human globin-related genes

β-thalassemia is an autosomal recessive monogenic disease that is caused by defects in the production of β-like globin chains. Activation of γ-globin gene and the increase in fetal hemoglobin expression have been demonstrated as one of the most important factors to ameliorate the clinical outcome of β-thalassemia patients. In this study, 202 genes or miRNAs associated with human hemoglobin gene expression from 1802 β-thalassemia patients were analyzed with target capture and next generation sequencing strategies in terms of functional variants that might affect hemoglobin gene expression. The subsequent bioinformatics analysis included assessments of sequence quality, the variants within the target regions and the 5′UTR with potential effects on upstream open reading frames (uORFs). Among the 41 variants in 5′UTR potentially affecting the uORFs identified in the study, two variants (chr19: 41859418 G>A and chr1:153606541 C>T) were experimentally validated with dual-luciferase assays to be capable of significantly down-regulating the expression of TGFB1 and CHTOP gene, respectively. The present study demonstrated a system suitable for evaluating the importance of variants in 5′UTRs affecting uORFs in 202 human genes associated with hemoglobin expression. Research with this approach could provide potential targets that may contribute to the clinical phenotypes and provide biomarkers for precise diagnosis of β-thalassemia.