Gap-PCR作为临床一线α-地中海贫血携带者筛查技术的应用评价

Evaluation of clinical application of gap-PCR as a routine method for α-thalassemia carrier detection

目的评价检测中国人3种常见的缺失型α-地中海贫血(地贫)基因的gap-PCR作为临床一线α地贫携带者筛查技术的可行性。方法 以双盲试验对随机抽取的382份血样同时采用gap-PCR分子筛查技术和血液学分析法分别检测α-地贫基因型和α-地贫表型,并以 Southern blot分析法作平行对照分析。结果在382份样品中,用gap-PCR法检出3种常见的α－地贫基因-SEA、α37和、-α^(+2)分别为21、7和3例、据此该市人群中α－地贫的基因携带率为8．12%。在这些阳性样品中有7例和3例分别检出自血液学表型正常(7/10)和缺铁性贫血(3/10)样品。这些结果与 Southern blot分析完全一致。血液学表型筛查法仅检出其中的21例(除2例α－地贫表型阳性未定型外),该法的假阴性率为32.3%。因血液学表型筛查漏检了7例静止型和3例轻型α－地贫样品,故此法总的漏检率为2.62%。结论 与血液学筛查法比较,gap－PCR分子筛查技术更具有特异性和可靠性,是临床上进行α－地贫基因携带者(尤其是静止型α－地贫)筛查的可选用的一线技术。

Objective To evaluate the feasibility of using gap-PCR for routine screening ofa-thalassemia in clinical laborato-ry. Methods A total of 382 clinical blood samples randomly collected from the populaton of Zhuhai city were screened forα-thalassemia determinants with hematological and gap-PCR method respectively in a double-blind manner. Parallel analysiswith Southem blotting was performed to verify the genotyping results by PCR. Results of the 382 samples tested, 3 commonα-thalassemia genes with genotypes of --SEA/αα, and -α^(4.2)/αα4 were detected in 21 (5.50%). 7 (1.83%) and 3 (0.79%)cascs respectively by gap-PCR, including 7 cases with normal phenotyPe and 3 casc of iron-deficiency anemia. The overall in-cidence of α-thalassemia was 8.12% in the population of Zhuhai city, as determined by gap-PCR, in tOtal agreement with theresultS by Southern blotting. Only 21 of the 31 α-thalassemia cases wcre identified by hematological analysis (besides 2 caseswith α-thalassemia phenotype undetermined), which had a false-negative rate of 32.3%. Seven silent α-thalassemia and 3 mildα-thalassemia cases failed to be detected by hematological analysis, resuting in a rate of 2.62% for failure of detection. Con-Clusion Gap-PCR method is specific and feasible as a better alternative forα-thalassemia screening, especially advantageousin detecting silent carriers in comparison with hematological method.