A Reliable Screening Protocol for Thalassemia and Hemoglobinopathies in Pregnancy

Abstract

Primary screening for thalassemia and hemoglobinopathies usually involves an accurate blood count using an expensive electronic blood cell counter A cheaper alternative method was tested by using a modified osmotic fragility (OF) test and a modified dichlorophenolindophenol (DCIP) test. Altogether 423 pregnant Thai women participated in this project. Hemoglobin patterns and globin genotypes were determined using an automated high-performance liquid chromatography analyzer and polymerase chain reaction analysis of alpha- and beta-globin genes. Among the 423 subjects, 264 (62.4%) carried thalassemia genes. The combined OF and DCIP tests detected all pregnant carriers of the 3 clinically important thalassemias, ie, alpha0-thalassemia, beta-thalassemia, and hemoglobin E with a sensitivity of 100.0%, specificity of 87.1%, positive predictive value of 84.5%, and negative predictive value of 100.0%, which show more effectiveness than these values for the standard method based on RBC counts. A combination of modified OF and DCIP tests should prove useful and applicable to prenatal screening programs for thalassemia and hemoglobinopathies in communities with limited facilities and economic resources.

Thalassemia and iron deficiency in a group of northeast Thai school children: relationship to the occurrence of anemia

“…Hemoglobin Constant Spring (Hb CS) and hemoglobin Pakse′ (Hb Pakse′), the α-chain variants, are less common. Carrier frequencies of 1-8% for Hb CS and approximately 1 to 2% for Hb Pakse′ have been reported in Thailand [9,10,21,22]. Generally, the heterozygous state of α + -thalassemia is not associated with anemia even in pregnancy [22,28].…”

Confirmation of the validity of using birth MCV for the diagnosis of alpha thalassemia trait

“…Medical literature does mention that α-thalassemia trait individuals are born with microcytosis. 5,10,11 However, there is no clear demarcation of the level of MCV and MCH where one can expect, with high confidence, to find α-thalassemia. 3,5,11, The work carried out in Thailand 9 took the MCV cut-off value of 95.…”

A Newly Modified Hemoglobin H Inclusion Test as a Secondary Screening for α⁰-Thalassemia in Southeast Asian Populations

“…Initial screening for thalassemia was performed at community hospitals before referral of the cases. All of them had a positive OF test or MCV <80 fl but were negative for DCIP screening for Hb E according to the current screening protocol for thalassemia in Thailand [3,4]. …”

“…While these two tests are used for screening α⁰-thalassemia and β-thalassemia carriers, Hb E is screened for using a dichlorophenolindophenol (DCIP) precipitation test. This screening protocol is simple, cheap and straightforward and has been used for thalassemia screening throughout Thailand and neighboring countries [3,4,5]. The protocol has been proven to be effective, with high sensitivity, i.e.…”