Abstract: Objective To analyse the relationship between genotype and phenotype of the deletional ^Gγ⁺(^Aγδβ)⁰-thalassemia with β thalassemia,and explore an approach to rapid prenatal diagnosis for compound heterozygotes of those defect with β-thalassemia. Methods A total of three members in a Chinese family who had a 1-year-old propositus with thalassemia major and requested prenatal diagnosis for the second pregnancy were studied.The results of phenotyping on hematological data including the RBC indices,quantification of HbF and HbA2 by Hb electrophoresis were obtained.Mutations of the β thalassemia were defined by reverse dot blot (RDB) genotyping analysis,and the deletion of ^Gγ⁺(^Aγδβ)⁰-thalassemia was analyzed using the method of gap-PCR. Results The propositus inherited the mutation of ^Gγ⁺(^Aγδβ)⁰-thalassemia gene from her mother's and inherited the frameshift mutation of CD17(A>T) from her father. Conclusion It is the first time to have performed prenatal diagnosis in Chinese family under risk of compound heterozygotes for ^Gγ⁺(^Aγδβ)⁰-thalassemia and β-thalassemia in mainland China,and this strategy to analyze the disease presented may be a valuable reference to the similar problem.

Key words: β-thalassemia, ^Gγ⁺(^Aγδβ)⁰-thalassemia, gene deletion, prenatal diagnosis

摘要： 目的 分析基因缺失突变导致的^Gγ⁺(^Aγδβ)⁰地中海贫血复合β地贫基因型与表型的关系,探讨^Gγ⁺(^Aγδβ)⁰地贫复合β地贫在高危β地贫家系的产前诊断方法。方法 以表型与基因型对一家系进行分析。表型分析采用红细胞相关指标与血红蛋白电泳分析;用反向点杂交技术筛查β地贫基因突变;用跨越断裂点的三引物聚合酶链反应直接分析法检测^Gγ⁺(^Aγδβ)⁰地贫缺失突变;并对高危β地贫家系进行了产前指导。结果 先证者(重症地贫)为一种^Gγ⁺(^Aγδβ)⁰地贫与β地贫双重杂合子,其^Gγ⁺(^Aγδβ)⁰地贫基因遗传自母方,β地贫遗传自父方。结论 诊断出极罕见的缺失型^Gγ⁺(^Aγδβ)⁰地贫基因与β地贫移码突变的双重杂合子导致重型地贫高危儿。本病例诊断采用的技术简便、快速,可用作同类事件的参考,避免β重型地贫高危儿的出生。

关键词: β地中海贫血, ^Gγ⁺(^Aγδβ)⁰地中海贫血, 基因缺失, 产前诊断