Discussion
inherited blood disorder, blood disorder, inherited hemoglobin disorders, consanguineous, anemia, hemoglobinopathy, beta thalassemia, micronutrient deficiencies, hemoglobinopathies, blood disorders, thalassemia, beta thalassemia intermedia
BETA THALASSEMIA, BLOOD DISORDER, DISEASE, OTHER HEMOGLOBINOPATHIES, BETA THALASSEMIA INTERMEDIA, BETA THALASSEMIA, HEMOGLOBINOPATHY, ANEMIA, WEST, IRON DEFICIENCY, HEMOGLOBINOPATHIES, BLOOD DISORDERS, DELETION, THALASSEMIA, ALPHA THALASSEMIA
Our community-based estimate of hemoglobinopathy prevalence in Bangladesh found 11% of women and 10% of children to have an inherited blood disorder, including alpha or beta thalassemia, hemoglobin E, hemoglobin S, hemoglobin D, or other abnormalities. The most prevalent hemoglobinopathy was alpha thalassemia, which was identified in 7% of women and 5% of children. Beta thalassemia and hemoglobin E were found in 2–3% of our sample. No severe cases of thalassemia or hemoglobinopathy were identified in this community-based sample, such as alpha or beta thalassemia intermedia or major, or hemoglobin E disease. Having any inherited blood disorder was associated with lower hemoglobin concentrations and higher odds of anemia. This association was largely driven by beta thalassemia. The evidence for this relationship was very strong among non-pregnant women, though similar associations were seen in the smaller samples of pregnant women and children. To our knowledge, we are presenting the first community-based estimate in Bangladesh that includes a comprehensive analysis of both alpha and beta thalassemia as well as other hemoglobinopathies.There is scarce literature on alpha thalassemia levels in Bangladesh to compare to our alpha thalassemia prevalence among women and children in the FAARM trial population, and existing studies report a range of estimates. One study, published in 2020, assessed alpha thalassemia in 413 newborns in three hospitals in three divisions of Bangladesh, including Sylhet, and found that 16% had at least one alpha thalassemia deletion [Interestingly, we did not identify any cases of the Southeast Asia deletion (-While research on beta thalassemia has been conducted more frequently in Bangladesh, few studies examined prevalence in a community-based sample. Of two studies that did, one assessed students from classes 9 and 10 (aged 14–16 years) [The prevalence of hemoglobin E in our rural Sylheti population (women: 3%; children: 2%) was slightly lower than other community-based prevalences reported in Bangladesh and the surrounding region. Khan et al. (2005) and Noor et al. (2020) reported somewhat higher prevalences in their sample of students (Sylhet: 4%; national: 6%) and adults (Sylhet: 9%; national: 9%). A study examining blood samples of hospital patients in West Bengal, India over ten years with a very large sample size (n = 119,336) and age range (5 months to 72 years) found a similar prevalence to our study (3%) [When examining beta thalassemia and hemoglobin E in mother–child pairs, we found a lower than the expected 50% chance of passing each condition to one’s child (Additional file Recent studies in Bangladesh have reported high anemia prevalences alongside low iron deficiency. This may point to alternative causes of anemia such as other micronutrient deficiencies (e.g., vitamin A, vitamin B12) or a potential role of inherited hemoglobin disorders. The latter were reported to be as high as 28% among women in Rangpur division in northeastern Bangladesh, driven by high levels of hemoglobin E [Our study had several strengths. The women and children included in this analysis were randomly selected from our FAARM trial population in a stratified way to ensure an even distribution over the study area. Thus, our sample was representative of our trial population and potentially other similar regions of Bangladesh. We had a large sample size and examined both young women and their children 6–37 months of age, a group which has not yet been reported on in Bangladesh. Another strength of our study is that we were able to identify thalassemia and hemoglobinopathies even in asymptomatic individuals since we did not limit our analysis to those with poor hematological indices. In addition, our chosen method (MLPA) to identify deletions/triplications in the alpha globin gene offers a substantial advantage in that it can also find previously unknown mutations-unlike other methods that can only assess previously known abnormalities.Our study also had some limitations. Though our sample is representative of our trial population, it is not representative of Habiganj district, Sylhet division, or Bangladesh nationally. As shown by other regional studies, inherited blood disorder prevalence may vary geographically, sometimes to quite a large degree. As marital partners are often likely to be found locally versus from long distances, in addition to the varying frequency of consanguineous unions, this likely contributes to pockets of very high prevalence of inherited blood disorders in certain regions of Bangladesh. A recent study estimated 7% of marriages as consanguineous in Bangladesh, higher in rural than urban areas, with the highest estimate from rural Sylhet at 10%. At the village level, estimates ranged from 2 to 41% [