Phupong Vorapong
Department of Obstetrics and Gynecology, Faculty of Medicine, Chulalongkorn University, Rama IV Road, Pathumwan, Bangkok 10330, Thailand.
J Med Assoc Thai. 2006 Apr;89(4):509-12.
Thalassemia is a common single gene disorder in Southeast Asia. a-thalassemia is a group of syndrome characterized by deficient production of the alpha-globin chain. Individuals with heterozygous alpha-thalassemia-1 are at risk of having a fetus that has Hemoglobin Bart's hydrops fetalis (Hb Bart's). Usually, when the hemoglobin electrophoresis in heterozygous alpha-thalassemia-1 is normal, the Mean Corpuscular Volume (MCV) is lowered. We report a case of increased cardiothoracic ratio that led to a diagnosis of Hb Bart's in a couple who had normal hemoglobin electrophoresis and low MCV.
A 23-year-old woman, gravida 2, Para 0-0-1-0, initially presented for antenatal care at 13 weeks pregnancy. Her MCV was 67 fentolitre, DiChlorophenol-IndolPhenol (DCIP) test was negative and hemoglobin electrophoresis was normal. Her husbands MCV was 67 fentolitre, and hemoglobin electrophoresis was normal. Cardiomegaly (an increased of the cardiothoracic ratio) was detected by ultrasonogram at 25 weeks of gestation. She and her husband were comprehensively counseled after an Hb Bart's was suspected. A cordocentesis was performed and the fetal blood was tested for hemoglobin electrophoresis. The result was later known and confirmed as Hb Bart's. The couple decided to terminate the pregnancy. The induced abortion was successful and the patient was discharged on the second day after the abortion. She was well at the 4-week follow-up.
A prenatal ultrasonographic screening should be conducted in couples who are suspected of being alpha-thalassemia-1 carriers when DNA study of alpha-globin gene cannot be performed. The increase of cardiothoracic ratio will help detect an early stage of Hb Bart's.
地中海贫血是东南亚常见的单基因疾病。α地中海贫血是一组以α珠蛋白链生成不足为特征的综合征。杂合子α地中海贫血-1患者怀有患血红蛋白巴氏水肿胎儿（Hb Bart's）的风险。通常，当杂合子α地中海贫血-1患者的血红蛋白电泳正常时，平均红细胞体积（MCV）会降低。我们报告一例心胸比率增加导致诊断为Hb Bart's的病例，该夫妇血红蛋白电泳正常且MCV较低。
一名23岁女性，孕2产0-0-1-0，孕13周时首次前来进行产前检查。她的MCV为67飞升，二氯酚靛酚（DCIP）试验阴性，血红蛋白电泳正常。其丈夫的MCV为67飞升，血红蛋白电泳正常。妊娠25周时超声检查发现心脏扩大（心胸比率增加）。在怀疑为Hb Bart's后，对她和她丈夫进行了全面咨询。进行了脐血穿刺，并对胎儿血液进行了血红蛋白电泳检测。结果后来得知并确诊为Hb Bart's。这对夫妇决定终止妊娠。引产成功，患者在流产后第二天出院。流产后4周随访时她情况良好。
当无法进行α珠蛋白基因的DNA研究时，对于疑似α地中海贫血-1携带者的夫妇应进行产前超声筛查。心胸比率增加有助于早期发现Hb Bart's。
