School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Laboratory of Medical Genetics, Qinzhou Maternal and Child Health Care Hospital, Qinzhou, Guangxi 535099, PR China.
School of Basic Medical Sciences, Xi'an Jiaotong University Health Science Center, Xi'an, Shaanxi 710061, China; Laboratory of Medical Genetics, Qinzhou Maternal and Child Health Care Hospital, Qinzhou, Guangxi 535099, PR China.
Gene. 2022 May 15;822:146332. doi: 10.1016/j.gene.2022.146332. Epub 2022 Feb 16.
Thalassemia is a monogenic disorder with a high carrier rate in the southern region of China. Most laboratories currently follow the protocol of testing hematologic indicators in individuals with positive hematologic indicators and then using the hot-spot mutation test kit. A novel thalassemia gene test is performed if there is a mismatch between the hematology and hot-spot mutation test results. However, due to the large population in southern China, some individuals carry complex α-globin gene cluster (CAGC) variants in NG_000006.1, which are difficult to detect using conventional thalassemia genetic analysis protocols, leading to missed or false genetic test results for individuals carrying these complex α-globin gene cluster variants. When an individual carries a complex α-thalassemia gene variant, and an individual carries a β- thalassemia gene variant, there may be clinical symptoms that might complicate clinical consultation and prenatal diagnosis if not accurately detected. Third-generation sequencing (TGS) enables long-read single-molecule sequencing with high detection accuracy, and long-length DNA chain reads in high-fidelity reads mode. TGS can be used to analyze high homology and rich GC DNA sequences.
Four samples that showed abnormalities in the thalassemia genetic test were studied using TGS, revealing that they carried genotypes with complex α-globin gene cluster variants, one of which was a complex variant αα anti3.7 α anti3.7 α 17.2.
TGS detects complex α-globin gene cluster variants. This study may provide a reference protocol for the use of TGS for the detection of complex α-globin gene cluster variants. TGS can reveal individuals with complex α-thalassemia genotypes in the population and improve the accuracy of genetic counseling and prenatal diagnosis.
地中海贫血是一种单基因疾病，在中国南方地区的携带率较高。大多数实验室目前遵循的方案是，对血液学指标阳性的个体进行血液学指标检测，然后使用热点突变检测试剂盒。如果血液学和热点突变检测结果不匹配，则进行新型地中海贫血基因检测。然而，由于中国南方人口众多，一些个体携带复杂的α-珠蛋白基因簇（CAGC）在 NG_000006.1 中的变体，这些变体很难用常规地中海贫血基因分析方案检测到，导致携带这些复杂α-珠蛋白基因簇变体的个体的基因检测结果出现漏检或假阳性。当个体携带复杂的α-地中海贫血基因突变，且个体携带β-地中海贫血基因突变时，如果不能准确检测，可能会导致临床症状复杂，使临床咨询和产前诊断变得复杂。第三代测序（TGS）可实现长读长单分子测序，具有高检测准确性和高保真读模式下的长 DNA 链读长。TGS 可用于分析高度同源和富含 GC 的 DNA 序列。
使用 TGS 研究了 4 例在地中海贫血基因检测中出现异常的样本，结果显示它们携带复杂的α-珠蛋白基因簇变异基因型，其中一种为复杂变异型αα抗 3.7α抗 3.7α17.2。
TGS 可检测复杂的α-珠蛋白基因簇变体。本研究可为 TGS 检测复杂的α-珠蛋白基因簇变体提供参考方案。TGS 可以揭示人群中携带复杂α-地中海贫血基因型的个体，提高遗传咨询和产前诊断的准确性。
