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.


CONCLUSIONS
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.
Zhou
Yu-Qiu
YQ
Women and Children's Healthcare Hospital of Zhuhai City, Zhuhai 519001, China.
Xiao
Ge-Fei
GF
Li
Li-Yan
LY
Li
Wen-Dian
WD
Liu
Zhong-Ying
ZY
Zhu
Lan-Fang
LF
Mo
Qiu-Hua
QH
Qu
Xin-Jun
XJ
Xu
Xiang-Min
XM
D004247:DNA / Q000235:genetics; D005260:Female; D006580:Genetic Carrier Screening / Q000379:methods*; D005838:Genotype; D006579:Heterozygote; D006801:Humans; D008297:Male; D010641:Phenotype; D016133:Polymerase Chain Reaction / Q000379:methods*; D017085:alpha-Thalassemia / Q000175:diagnosis / Q000235:genetics*
D004247:DNA