Screening for beta thalassemia trait in a heterogeneous university-based population in Delhi-NCR, India

Thalassemia is a major monogenic blood disorder, with India bearing a substantial burden. Although carrier screening is the most effective preventive strategy, inconsistent criteria, borderline HbA2 values, diverse mutations, and limited HbE detection hinder effectiveness. This study determines the prevalence of molecularly confirmed beta thalassemia trait (BTT) and HbE detected through a large-scale screening approach among young adults in Delhi-National Capital Region (NCR) and develops a potential scalable model for university-based carrier detection.

We recruited 4886 young adults aged 18-35 years from universities in Delhi-NCR. All blood samples underwent CBC and HPLC analysis, with selected samples subjected to genetic analysis using ARMS-PCR and Sanger sequencing.

The prevalence of molecularly confirmed BTT and HbE trait detected through the study screening approach was 1.6% and 0.4%, respectively. Overall, 2% showed elevated HbA2 with low MCV and MCH, while 5.1% of carriers had borderline HbA2. Five common beta thalassemia mutations accounted for 84.8% of cases. Nearly 21% of samples with HbA2 4-9% showed no mutations on genetic testing. HbA2 4-9% plus low MCV and MCH showed the highest PPV, with 92% sensitivity and 88% specificity. No significant differences in BTT distribution were observed by region, religion, or social category.

Large-scale screening for BTT among young adults in university-based settings may facilitate early carrier identification. HbA2 levels of 4-9% combined with low MCV and MCH appear to be an effective first-tier screening criterion, while further criteria are needed to identify and prioritize individuals with borderline HbA2 levels (3.2-3.9%) for molecular confirmation. Future studies should focus on developing and validating robust, context-appropriate population-level screening protocols for BTT in India.