毛细管等电聚焦电泳定量分析健康成人及地中海贫血携带者的Hb A2

目的 对等电聚焦毛细管电泳(capillary isoelectric focusing，CIEF)检测血红蛋白A2(HbAt)含量做出用于筛查地中海贫血(地贫)携带者的方法学评价。方法 收集105名健康成人、93例经常规地贫筛查有阳性表型的连续临床样品。通过正常人样品分析比较CIEF测定HbA2与Helena Spife combo电泳系统结果的一致性；通过比较样品内和样品间Hb A2的CIEF测定值的变异系数评价该法的精确度和稳定性；通过分析阳性样品的基因型来评价CIEF检测地贫的准确性。结果 用CIEF分析当地健康人的Hb A2正常参考值为3．59％～5．23％。CIEF结果与常规血红蛋白电泳结果具有良好的线性关系；以基因分析为确诊标准，用CIEF检测Hb A2含量，及结合红细胞指数阳性测定值所筛查的87例α-地贫或β-地贫携带者、6例成人血红蛋白E病例样品均被准确诊断，未见假阳性或假阴性结果。结论 等电聚焦毛细管电泳是一种快速高效、高稳定性、高精确度的HbA2测定方法，可用作地贫携带者的常规筛查手段。

Use of capillary electrophoresis to determine hemoglobin A2 in healthy adults and α- and β-thalassemia carriers

OBJECTIVE: To evaluate the capillary isoelectric focusing (CIEF) method for the estimation of blood hemoglobin A2 (Hb A2) concentrations in routine thalassemia screening. METHODS: A total of 105 samples from healthy adults and 93 samples with positive phenotypes were collected by routine thalassemia screening. CIEF was compared with Helena spife combo electrophoresis system for Hb A2 measurement and its precision and reproducibility were tested by analyzing intra-assay or inter-assay coefficient of variations(CVs). The reliability and veracity of Hb A2 measurement by CIEF for the detection of alpha- and beta- thalassemia including Hb E were evaluated by genotyping of 93 consecutive samples for routine thalassemia screening. RESULTS: By us e of CIEF for measurement of Hb A2 in a local healthy adult population, the range of reference value(3.59%-5.23%) was obtained. The results of CIEF showed good linearity relation to that of conventional Hb electrophoresis assay. All thalassemia carriers (43 cases of alpha-thals and 44 of beta-thals) or Hb E carriers (6 cases) presumptively identified by the present CIEF for the quantification of Hb A2, combined with routine RBC parameters for indicating microcytosis and hypochromia were confirmed to be the heterozygous or compound heterozygous defects of alpha- or beta- globin gene by molecular diagnosis, without any false positive or false negative results. CONCLUSION: The measurement of Hb A2 by CIEF method is rapid, precise and reproducible; it could be used in routine screening for alpha- or beta- thalassemia.