Department of Medical Genetics and Prenatal Diagnosis, Huizhou First Maternal and Child Health Care Hospital, Huizhou, Guangdong, China.
Berry Genomics Corporation, Beijing, China.
Clin Biochem. 2022 Oct;108:46-49. doi: 10.1016/j.clinbiochem.2022.06.015. Epub 2022 Jul 2.
Thalassemia is the most frequent recessive Mendelian inherited monogenic disease worldwide, and is characterized by the impaired synthesis of globin chains due to disease-causing variants in α- or β-globin genes. There are many conventional methods to diagnose thalassemia but all of them have limitations.
We present the case of a 37-year-old female with abnormal values of routine hematological indices who was admitted for genetic screening of thalassemia. Genomic DNA was extracted and used for genetic assays covering the known and potential novel genotypes in HBA and HBB genes using a suspension-array system, gap-polymerase chain reaction (Gap-PCR), PCR-reverse dot blot (PCR-RDB) and multiplex ligation-dependent probe amplification (MLPA). Finally, using long-read single-molecule real-time (SMRT) sequencing, we first confirmed the case with a novel 15.8 kb deletion located in the HBA gene (Chr16:163886-179768, GRch38/hg38).
Our results showed that long-read SMRT sequencing has great advantages in the detection of rare α-globin gene variants. This study may provide a reference protocol for the use of long-read SMRT sequencing for the detection of known and potential novel genotypes of thalassemia in the population and improve the accuracy of genetic counseling and prenatal diagnosis.
地中海贫血是全球最常见的隐性孟德尔遗传单基因疾病，其特征是由于α-或β-珠蛋白基因中的致病变异导致珠蛋白链合成受损。有许多常规方法可用于诊断地中海贫血，但都存在局限性。
我们报告了一例 37 岁女性的病例，其常规血液学指标异常，因地中海贫血的基因筛查而入院。提取基因组 DNA，用于使用悬浮液阵列系统、Gap-聚合酶链反应 (Gap-PCR)、PCR-反向斑点印迹 (PCR-RDB) 和多重连接依赖性探针扩增 (MLPA) 对 HBA 和 HBB 基因中的已知和潜在新型基因型进行遗传检测。最后，通过长读长单分子实时 (SMRT) 测序，我们首次证实了该病例存在 15.8 kb 的新型缺失，位于 HBA 基因中（Chr16:163886-179768，GRch38/hg38）。
我们的结果表明，长读长 SMRT 测序在检测罕见的α-珠蛋白基因突变方面具有很大的优势。本研究可为长读长 SMRT 测序用于检测人群中已知和潜在新型地中海贫血基因型提供参考方案，并提高遗传咨询和产前诊断的准确性。
