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目的对一例国人罕见的缺失型β地中海贫血及其家系进行基因分析,以期为地中海贫血的预防、临床诊断及遗传咨询提供科学的参考依据。方法采用血细胞分析仪及全自动快速电泳分析系统进行血液学分析;采用导流杂交法进行常规α和β地中海贫血基因检测;采用多重链接探针扩增技术(multi-link probe amplification technology,MLPA)、DNA测序、缺口PCR(Gap-PCR)及血红蛋白持续增多症缺失型电泳等技术分析其罕见基因型。结果通过血红蛋白持续增多症缺失型电泳技术检测到先证者为中国人罕见的越南型缺失型β地中海贫血;通过导流杂交法检测到先证者母亲为中国人常见的CD41/42基因突变;通过血红蛋白持续增多症缺失型电泳技术检测到先证者父亲及其胞弟为罕见的越南型缺失型β地中海贫血。先证者及胞弟的罕见越南型缺失型β地中海贫血遗传来源是其父亲。结论越南型缺失型β地中海贫血是一种罕见的β珠蛋白基因缺失,血常规有小细胞低色素的表现,血蛋白电泳血红蛋白F(hemoglobin F,HbF)常常增高明显。当出现血液学表型与基因型不符时,应注意进一步做罕见基因型的检测以避免漏诊或误诊,这有助于指导临床诊断、人群筛查和遗传咨询。
OBJECTIVE: To provide a scientific reference for the prevention, clinical diagnosis and genetic counseling of thalassemia in a rare Chinese missing β-thalassemia and its pedigree. Methods Hematology was analyzed by hematology analyzer and automated rapid electrophoresis system. Genes of alpha and beta thalassemia were detected by flow-guide hybridization. Multi-link probe amplification technology (MLPA) , DNA sequencing, gapped PCR (Gap-PCR) and hemoglobin deficiency syndrome. Results The deletion type β-thalassemia was rare in Chinese with probands detected by deletion electrophoresis. The CD41 / 42 gene mutation was detected by flow-through hybridization in Chinese of the proband’s mother. Through the lack of hemoglobin continued polysemia electrophoresis detected probands father and his brother as rare Vietnamese-type beta-thalassemia. The proband and brother’s rare genetic origin of missing-type beta thalassemia is their father. CONCLUSIONS: Vietnam-type deletion β-thalassemia is a rare deletion of β-globin gene, showing the expression of small cell hypochromia in blood. The hemoglobin F (HbF) is often increased significantly. When hematological phenotypes do not match genotypes, further testing of rare genotypes should be made to avoid misdiagnosis or missed diagnosis, which can be helpful in guiding clinical diagnosis, population screening and genetic counseling.