异常血红蛋白合并遗传性持续性胎儿血红蛋白增多症患者一例的基因分析

摘要

目的 对1例异常血红蛋白合并遗传性持续性胎儿血红蛋白增多症(HPFH)患者进行基因分析.方法 患者男,26岁,2010年9月到广州金域医学检验中心进行体检,经血液学分析、血红蛋白电泳、红细胞渗透脆性分析后,疑为异常血红蛋白合并HPFH病患者.应用常规血液学检查、碱性琼脂糖凝胶血红蛋白电泳对先证者进行表型分析；通过对HBB基因直接测序检测异常血红蛋白的突变类型；应用多重连接酶依赖探针扩增技术(MLPA)检测整个β-珠蛋白基因簇有无缺失及缺失的大致范围；应用跨越断裂点聚合酶链反应(gap-PCR)进行跨越断裂点PCR扩增,对此扩增产物进行基因测序分析,并将其结果与参考序列NC_000011.9进行比对,判断具体的断裂位点.结果 通过对HBB基因进行直接测序,发现该异常血红蛋白为Ta-Li( HBB:c.250G＞T),通过MLPA结合gap-PCR以及对产物进行基因测序,发现患者存在β-珠蛋白基因的大片段缺失,缺失范围为NC_000011.9:g.5222878_5250288del,即患者的基因型为异常血红蛋白Ta-Li合并东南亚型遗传性持续性胎儿血红蛋白增多症(SEA-HPFH).结论 联合应用MLPA、gap-PCR和基因测序技术可能有助于明确先证者的基因型.%Objective To investigate the genotype of a case with abnormal hemoglobin combined with hereditary persistence of fetal hemoglobin (HPFH).Methods Male patient,26 years old,were suspected abnormal hemoglobin combined with HPFH after receiving medical examination including hematology exmination,hemoglobin electrophoresis,erythrocyte osmotic fragility analysis in Guangzhou Kingmed Diagnostics in September 2010.Routine examination of anemia and hemoglobin electrophoresis at alkaine pH on agarose gels were applied to analyze the phenotype.Direct sequencing of the complete HBB gene was utilized to identify the hemoglobin variant.Multiplex ligation-dependent probe amplification (MLPA) assay was used to identify the presence of β-globin gene cluster deletion.Gap polymerase chain reaction (gap-PCR) was used to amplify the HBB gene fragment across the breakpoint,and the deletion breakpoint was characterized by direct sequencing the gap-PCR product and comparing the sequencing result with the reference sequence NC_000011.9.Results By direct sequencing of the complete HBB gene,the patient in this study was found to carry a hemoglobin Ta-Li (HBB:c.250G ＞ T) mutation.By combining use of MLPA and gap-PCR with gene sequencing,we found that it had a gross deletion in the β-globin gene cluster,the deletion region was NC_000011.9:g.5222878_5250288del.Therefore,the genotype of this subject was SEA-HPFH combined with abnormal hemoglobin Ta-li.Conclusion Combining application of MLPA and gap-PCR with gene sequencing can help to make sure the genotype.