异常血红蛋白（Hb J-Bangkok）合并β地中海贫血的临床表型分析

Analysis of clinical phenotypes of compound heterozygotes of Hb J-Bangkok and β-thalassemia

目的分析异常血红蛋白[HbJ—Bangkok（βCDS6〉GAC）]杂合子及其合并β地中海贫血（简称β地贫）突变的双重杂合子的血液学指标，分析携带该异常血红蛋白突变的表型特征及其对β地中海贫血表型的修饰作用。方法收集1个携带有HbJ—Bangkok／β-地贫突变的家系以及3例散发的Hb J—Bangkok携带者样本，对其进行血常规分析和血红蛋白电泳，分析并测定α和β珠蛋白基因型。结果家系中的父亲和3例散发样本均为Hb J—Bangkok杂合子，红细胞参数均正常，但血红蛋白电泳显示有Hb J异常带，无其他临床表型。先证者为HbJ—Bangkok合并B地贫IVS-Ⅱ-654突变的双重杂合子，其血液学表型与单纯β地贫杂合子类似，具有小细胞低色素贫血特征，血红蛋白电泳结果HbA2上升，并有高含量Hb J异常带。结论单纯HbJ—Bangkok杂合子无临床表型。Hb J-Bangkok合并B地贫突变不会加重其临床症状。因此携带Hb J—Bangkok突变不会对个体的临床表型产生影响。当HbJ—Bangkok突变携带者与β地贫携带者婚配时无需进行产前诊断。

Objective To analyze hematological characteristics of compound heterozygotes of Hb J- Bangkok and β-thalassemia, and to explore the influence of Hb J-Bangkok on the phenotype of β- thalassemia. Methods Peripheral blood samples from a patient carrying Hb J-Bangkok and a/t-thalassemia mutation, her family members and three sporadic Hb J-Bangkok carriers were collected. RBC analysis and hemoglobin electrophoresis were performed. Genotypes of a- and β-globin genes were analyzed. Results The father of the proband and the three sporadic cases were single carriers of Hb J-Bangkok. All of them were asymptomatic and have normal hematological parameters except for an abnormal hemoglobin band detected on hemoglobin electrophoresis. The proband was a compound heterozygote for Hb J-Bangkok and β-thalassemia mutation IVS-β-654. She presented typical β-thalassemia trait, featuring hypochromic microeytie anemia and increased Hb Az level. An abnormal hemoglobin band was also detected. Conclusion Carriers of Hb J-Bangkok alone are asymptomatic. Co-existence of Hb J-Bangkok and β-thalassemia may not aggravate the pbenotype. Therefore, couples with one carrying Hb J-Bangkok marrying and another carrying a β-thalassemia mutation do not require prenatal diagnosis.