Objective: To determine the prevalence, molecular characteristics and hematological study of thalassemia in Tha Kradarn Subdistrict Chachoengsao Province.
Material and Method: The present study population consisted of 266 participants from Moo 19 Baan Na-Ngam, Chachoengsao Province, Thailand. After blood collection, all samples were screened for thalassemia by initial screening with the OF and DCIP tests and additional testing by CBC, RBC indices, hemoglobin typing and determination of Hb A2 and Hb E. All common α-thalassemia mutations were determined using the PCR with allele specific primers and Gap PCR for common deletions.
Results: The prevalence of α-thal 1, α-thal 2 and β-thal were found as 2.72%, 11.26% and 0.97%, respectively. Regarding the abnormal hemoglobins, the prevalence of Hb E, Hb Constant Spring and Hb Pakse was 38.45%, 3.69% and 0.78%, respectively. MCV and MCH were significantly different between β-thalassemia as well as α-thal 1 carriers and normal subjects. In all α-thal 1 traits, it was found that the MCV and MCH were less than 75 fL and 25 pg, therefore, these parameters can be used for α-thal 1 screening.
Conclusion: In the present study, the prevalence of thalassemia was similar to previous studies. Moreover, using the combination of OF and DCIP tests compared with MCV, MCH and DCIP tests for the initial thalassemia screening, it was found that the OF and DCIP tests gave more false positive results, which increased the need for further Hb typing. Hence, the MCV and MCH combined with DCIP tests provide cost minimization and practical for a large population-based screening program.

Keywords: Thalassemia, OF test, DCIP test, RBC indices, Hb typing, PCR for α-thalassemia