【摘要】 我们分子鉴别了一个缺失型中国(A_γδβ)°-地贫家系。先证者为这一缺失的纯合子,具有中度贫血症状。家系的另五个成员均为这一缺失的杂合子,其胎儿血红蛋白(HbF)为16—21％,接近或达到HPFH杂合子的HbF水平,并且几乎不表现贫血症状。限制性内切酶图谱分析证明了β-珠蛋白基因簇内的DNA顺序缺失,缺失的5′端点位于Aγ基因IVSⅡ内,3′端点在β-珠蛋白基因下游区远端,距HPFH-2的3′缺失端点上游区约11kb。缺失的总长度约为80kb。本文讨论了这一缺失导致胎儿血红蛋白在成人中持续活跃表达的可能机制。更多还原

【Abstract】 A DNA deletion in the β-globin gene cluster that increases fetal hemoglobin (HbF) in a Chinese (Arδβ)°-thalassemia family has been identified and mole-cularly characterized. The proband is a homozygote for this deletion mutation, with milder anemia than that of typical homozygotes of β-thalassemia. The other members of the family are heterozygotes of this mutation, with 16-20% HbF, closing HbF level of heterozygotes of hereditary persistance of fetal hemoglobin(HPFH), and they do not show any anemic symptom.The physical mapping of DNA shows the DNA deletion in the β-globin gene cluster. The 5’ breakpoint of the deletion is within the IVS II of Ar-globin gene. The 3’ breakpoint is located in the distant downstream of β-globin gene, about 11 kb of upstream of the 3’ breakpoint of HPFH-2. The total length of the deletion is about 80kb. The possible mechanism of persist active expression of fetal globin gene in adult resulted by the deletion is discussed.更多还原