一例中间型α地中海贫血[--^(SEA)/α^(CD90-92(-AGCTTCGG))α]的基因诊断及家系分析

Gene diagnosis and pedigree analysis: a case of intermediate α-thalassemia[--^(SEA)/α^(CD90-92(-AGCTTCGG))α]

目的:对一个罕见的非缺失型血红蛋白H病(hemoglobin H disease,Hb H)家系进行基因诊断与遗传学分析。方法:采集先证者及其父母的外周静脉血样,进行血常规、血红蛋白电泳以及α地贫基因常规检测,用二代测序检测潜在的致病变异,并通过Sanger测序进行家系验证。结果:先证者为HbA2:c.272_279delAGCTTCGG罕见变异复合东南亚型α地贫缺失(--^(SEA))患者,二者分别遗传自母亲和父亲。结论:HbA2:c.272_279delAGCTTCGG罕见变异复合东南亚型α地贫缺失(--^(SEA))是导致先证者非缺失型Hb H的原因。上述发现为该家系的遗传咨询与产前诊断提供了依据。

Objective To explore the genetic basis for a Chinese pedigree affected with a rare non-deletional hemoglobin H disease(Hb H disease).Methods Peripheral venous blood samples of the proband and his parents were collected and subjected to routine blood testing,hemoglobin electrophoresis and screening for common mutations associated with thalassemia.Next generation sequencing was carried out to detect potential pathogenic variant,and candidate variant was verified by Sanger sequencing.Results The proband was found to harbor a rare HbA2:c272_279delAGCTTCGG variant,which compounded with southeast Asian type deletion ofα-thalassemia(--^(SEA)).The two mutations were respectively inherited from his mother and father.Conclusion The rare HbA2:c.272_279delAGCTTCGG variant compounded with Southeast Asian typeα-thalassemia(--^(SEA))probably underlay the non-deletion Hb H in the proband.Above finding has enabled genetic counseling and prenatal diagnosis for this family.