Effective routine screening for a - thalassemia 1 carroer with the SEA deletion

Abstract

In order to provide rapid method for identifying a - thalassemia 1 in massive screening, we have tested a simple screening strategy using simple blood test and real-time PCR.  Study was done at our ongoing thalassemia screening at the Thalassemia Service Unit, Faculty of Associated Medical Sciences, Khon Kaen University. Initial screening was done for all samples using a modified one tube osmotic fragility test (OF test) and RBC indices obtained using standard blood cell counter. Those who had positive OF test results or MCV less than 80 fl were subjected to further PCR analysis for detection of a - thalassemia 1 (SEA deletion) by two PCR methods. In the first method, a - thalassemia 1 determinant was identified using a conventional GAP-PCR routinely run in our laboratory. In the second method, identification of a - thalassemia 1 (SEA) was carried out using a real-time PCR with SyBr green I and melt curve analysis. The SEA determinant generated specific melt curve with Tm of 86 + 1 ^๐ C. Among 98 subjects who were positive at the initial screening, a - thalassemia 1 (SEA deletion) was detected in 22 (22.5 %) of them by both PCR methods. These included 14 a – thalassemia 1 carriers, 3 patients with Hb H disease and 5 subjects with double heterozygote for a-thalassemia 1 and Hb E. No a - thalassemia 1 was detected in the remaining 76 cases. This data demonstrates that identification of a - thalassemia 1 in routine practice with large number of samples can be effectively done using a combination of OF test or MCV and a real-time PCR which should prove useful in a prevention and control program of thalassemia in area with high prevalence.