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 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.