Ning Sisi, Luo Yudi, Liang Yi, Xie Yuling, Lu Yinghong, Meng Binrong, Pan Jinjie, Xu Ruofan, Liu Yinyin, Qin Yunrong
Department of Clinical Laboratory, Yulin Women and Children Health Care Hospital, Yulin, Guangxi Zhuang Autonomous Region, China.
Berry Genomics Corporation, Beijing, China.
Clin Chim Acta. 2022 Oct 1;535:7-12. doi: 10.1016/j.cca.2022.07.020. Epub 2022 Aug 6.
Thalassemia is one of the most common hemoglobinopathies. Thalassemia is mainly caused by the loss and/or deficiency of one or more globin chains in hemoglobin. The copy number variant (CNV) of α-globin gene is one of the important factors affecting the clinical phenotype of β-thalassemia. The precise detection for this type of variation is needed.
Peripheral blood of a 33-year-old man and his family members were collected. Complete blood counts and serum iron levels were measured for participants. Genomic DNA was extracted from all family members. Routine genetic analysis of thalassemia was performed to determine the genotype. Additional PCR-electrophoresis and Multiplex ligation dependent probe amplification (MLPA) were conducted. Single-molecule real-time technology(SMRT) was then performed as a validation assay and further characterization of the variant for family members.
PCR-electrophoresis and MLPA found a new variant, but the exact genotype could not be determined. At last, SMRT identified the new variant as a rearrangement of the α-globin gene cluster named αHKαα (NC_000016.9:g.169818_174075dup169818_174075dup173302_177105del), which contained both the -α and αααα crossover junctions. Carriers of the novel CNV show normal clinical phenotype according to the hematological results.
We have identified an unreported CNV (αHKαα) in α-globin gene cluster. The novel CNV not only demonstrates the accuracy and efficiency of our combining strategy in detecting unknown CNVs, but also enriched the variant spectrum of thalassemia.
地中海贫血是最常见的血红蛋白病之一。地中海贫血主要由血红蛋白中一条或多条珠蛋白链的缺失和/或缺陷引起。α-珠蛋白基因的拷贝数变异（CNV）是影响β-地中海贫血临床表型的重要因素之一。需要对这类变异进行精确检测。
采集一名33岁男性及其家庭成员的外周血。对参与者进行全血细胞计数和血清铁水平检测。从所有家庭成员中提取基因组DNA。进行地中海贫血的常规基因分析以确定基因型。另外进行了聚合酶链反应-电泳（PCR-电泳）和多重连接依赖探针扩增（MLPA）。然后采用单分子实时技术（SMRT）作为验证试验，并对家庭成员的变异进行进一步表征。
PCR-电泳和MLPA发现了一个新变异，但无法确定其确切基因型。最后，SMRT将该新变异鉴定为α-珠蛋白基因簇的重排，命名为αHKαα（NC_000016.9:g.169818_174075dup169818_174075dup173302_177105del），其中包含-α和αααα交叉连接点。根据血液学结果，该新型CNV的携带者表现出正常的临床表型。
我们在α-珠蛋白基因簇中鉴定出一种未报道的CNV（αHKαα）。这种新型CNV不仅证明了我们联合策略在检测未知CNV方面的准确性和效率，还丰富了地中海贫血的变异谱。
