Population Screening and Prevention Strategies for Thalassemias and other Hemoglobinopathies of Eastern India: Experience of 18,166 cases

Abstract

We evaluated population screening programs (1999–2011), conducted by the Thalassaemia Foundation, Kolkata, India, for the first time in Eastern India in different districts of West Bengal, for prevention of thalassemia comprising screening of heterozygotes and β-thalassemia intermedia (β-TI) cases [β⁺, β⁺⁺, β⁰/β⁺, β^E/β^E (codon 26 or HBB: c.79G > A), Hb-E-β-thalassemia (Hb E-β-thal)]. Among 18,166 cases, we found 2092 heterozygotes and 2245 β-TI individuals (who had no information about their disorders). Results were evaluated with standard hematological analyses including erythrocyte indices, hemoglobin (Hb) typing and quantification. Participants were divided into five groups (children, pre-marriage cases, pre-pregnancy cases, affected family members, pregnant women). The objectives of this evaluation were to fix cut-off values of red blood cells (RBCs), mean corpuscular volume (MCV), mean corpuscular Hb (MCH), red blood cell distribution width (RDW) and Hb A₂, as the standard World Health Organization (WHO) guidelines were not strictly followed in mass-scale screening programs. We have observed many dilemmas in considering the status of the thalassemia subject, due to presence of some other clinical conditions such as iron deficiency anemia, α-thalassemia (α-thal), δ-thalassemia (δ-thal), clinically silent Hb variants, and some cases of non hemoglobinopathies (such as pregnancy) along with thalassemia. The MCV values varied greatly in different conditions of hemoglobinopathies, whereas MCH provided a more stable measurement. We found an MCH value of <27.0 pg is a suitable cut-off point for screening in this population. Participants with an MCH of <27.0 pg should be investigated further to confirm or exclude a diagnosis of β-thal trait.

• β-Thalassemia (β-thal)
• Hb A₂/E
• Hb E-β-thalassemia (Hb E-β-thal)
• mean corpuscular Hb (MCH)
• mean corpuscular volume (MCV)
• population screening

Declaration of interest

The authors acknowledge the Thalassaemia Foundation, Salt Lake, Kolkata-700064, West Bengal, India, for their initial financial and infrastructural support and also the Institute of Genetic Medicine and Genomic Science (IGMGS), Kolkata, West Bengal, India for their financial and infrastructural support in the latter part of the project. TC acknowledges the West Bengal University of Health Sciences (WBUHS), Kolkata, West Bengal. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.