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

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地喧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－地贫贱有型，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，－α3．7和－α42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8．123，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。

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

OBJECTIVE: To evaluate the feasibility of using gap-PCR for routine screening of alpha-thalassemia in clinical laboratory. METHODS: A total of 382 clinical blood samples randomly collected from the population of Zhuhai city were screened for alpha-thalassemia determinants with hematological and gap-PCR method respectively in a double-blind manner. Parallel analysis with Southern blotting was performed to verify the genotyping results by PCR. RESULTS: Of the 382 samples tested, 3 common alpha-thalassemia genes with genotypes of --(SEA)/alpha alpha, -alpha(3.7)/alpha alpha and -alpha(4.2)/alpha alpha were detected in 21 (5.50%), 7 (1.83%) and 3 (0.79%) cases respectively by gap-PCR, including 7 cases with normal phenotype and 3 case of iron-deficiency anemia. The overall incidence of alpha-thalassemia was 8.12% in the population of Zhuhai city, as determined by gap-PCR, in total agreement with the results by Southern blotting. Only 21 of the 31 alpha-thalassemia cases were identified by hematological analysis (besides 2 cases with alpha-thalassemia phenotype undetermined), which had a false-negative rate of 32.3%. Seven silent alpha-thalassemia and 3 mild alpha-thalassemia cases failed to be detected by hematological analysis, resulting in a rate of 2.62% for failure of detection. CONCLUSION: Gap-PCR method is specific and feasible as a better alternative for alpha-thalassemia screening, especially advantageous in detecting silent carriers in comparison with hematological method.