Umbilical Cord Blood Screening for the Detection of Common Deletional Mutations of α-Thalassemia in Bangladesh

Current Status of Newborn Bloodspot Screening Worldwide 2024: A Comprehensive Review of Recent Activities (2020-2023)

Newborn bloodspot screening (NBS) began in the early 1960s based on the work of Dr. Robert "Bob" Guthrie in Buffalo, NY, USA. His development of a screening test for phenylketonuria on blood absorbed onto a special filter paper and transported to a remote testing laboratory began it all. Expansion of NBS to large numbers of asymptomatic congenital conditions flourishes in many settings while it has not yet been realized in others. The need for NBS as an efficient and effective public health prevention strategy that contributes to lowered morbidity and mortality wherever it is sustained is well known in the medical field but not necessarily by political policy makers. Acknowledging the value of national NBS reports published in 2007, the authors collaborated to create a worldwide NBS update in 2015. In a continuing attempt to review the progress of NBS globally, and to move towards a more harmonized and equitable screening system, we have updated our 2015 report with information available at the beginning of 2024. Reports on sub-Saharan Africa and the Caribbean, missing in 2015, have been included. Tables popular in the previous report have been updated with an eye towards harmonized comparisons. To emphasize areas needing attention globally, we have used regional tables containing similar listings of conditions screened, numbers of screening laboratories, and time at which specimen collection is recommended. Discussions are limited to bloodspot screening.

Thalassemia and hemoglobinopathy prevalence in a community-based sample in Sylhet, Bangladesh

BACKGROUND

Inherited blood disorders affect 7% of the population worldwide, with higher prevalences in countries in the "thalassemia belt," which includes Bangladesh. Clinical management options for severely affected individuals are expensive; thus, targeted government policies are needed to support prevention and treatment programs. In Bangladesh, there is a lack of data, in particular community-based estimates, to determine population prevalence. This study aims to estimate the prevalence of a wide range of hemoglobinopathies and their associations with anemia in a community-based sample of women and young children in rural Sylhet, Bangladesh.

METHODS

Capillary blood samples from 900 reproductive-aged women and 395 children (aged 6-37 months) participating in the Food and Agricultural Approaches to Reducing Malnutrition (FAARM) trial in two sub-districts of Habiganj, Sylhet Division, Bangladesh were analyzed for alpha thalassemia, beta thalassemia, and other hemoglobinopathies. We examined the association of each inherited blood disorder with hemoglobin concentration and anemia using linear and logistic regression.

RESULTS

We identified at least one inherited blood disorder in 11% of women and 10% of children. Alpha thalassemia was most prevalent, identified in 7% of women and 5% of children, followed by beta thalassemia and hemoglobin E in 2-3%. We also identified cases of hemoglobin S and hemoglobin D in this population. Having any of the identified inherited blood disorders was associated with lower hemoglobin values among non-pregnant women, largely driven by alpha and beta thalassemia. Pregnant women with beta thalassemia were also more likely to have lower hemoglobin concentrations. Among children, we found weak evidence for a relationship between hemoglobinopathy and lower hemoglobin concentrations.

CONCLUSIONS

We found a high prevalence of alpha thalassemia among both women and children in rural Sylhet, Bangladesh-higher than all other identified hemoglobinopathies combined. Community-based estimates of alpha thalassemia prevalence in Bangladesh are scarce, yet our findings suggest that alpha thalassemia may comprise the majority of inherited blood disorders in some regions of the country. We recommend that future research on inherited blood disorders in Bangladesh include estimates of alpha thalassemia in their reporting for public health awareness and to facilitate couples  counseling.

α- and β-Globin Gene Mutations in Individuals with Hemoglobinopathies in the Chattogram and Sylhet Regions of Bangladesh

Hemoglobinopathies, including α- and β-thalassemias and sickle cell disease, are among the most widely disseminated hereditary blood disorders worldwide. Bangladesh is considered a hotspot for hemoglobinopathies, and these diseases cause a significant health concern in the country. However, the country has a dearth of knowledge on the molecular etiology and carrier frequency of thalassemias, primarily due to a lack of diagnostic facilities, limited access to information, and the absence of efficient screening programs. This study sought to investigate the spectrum of mutations underlying hemoglobinopathies in Bangladesh. We developed a set of polymerase chain reaction (PCR)-based techniques to detect mutations in α- and β-globin genes. We recruited 63 index subjects with previously diagnosed thalassemia. Along with age- and sex-matched control subjects, we assessed several hematological and serum indices and genotyped them using our PCR-based methods. We identified that parental consanguinity was associated with the occurrence of these hemoglobinopathies. Our PCR-based genotyping assays identified 23 HBB genotypes, with the codons 41/42 (-TTCT) (HBB: c.126_129delCTTT) mutation leading the spectrum. We also observed the presence of cooccurring HBA conditions, of which the participants were not aware. All index participants in this study were on iron chelation therapies, yet we found they had very high serum ferritin (SF) levels, indicating inefficient management of the individuals undergoing such treatments. Overall, this study provides essential information on the hemoglobinopathy mutation spectrum in Bangladesh and highlights the need for nationwide screening programs and an integrated policy for diagnosing and managing individuals with hemoglobinopathies.

Genetic counseling in the context of Bangladesh: current scenario, challenges, and a framework for genetic service implementation

With the advancements in genetics and genomics in the twenty-first century, genetic services have become an integral part of medical practices in high-income and upper-middle-income countries. However, people living in low and lower-middle-income countries (LICs and LIMCs), including Bangladesh, are rather underprivileged in receiving genetic services. Consequently, genetic disorders are emerging as a significant public health concern in these countries. Lack of expertise, high expense, the dearth of epidemiological data, insufficiently updated medical education system, poor infrastructure, and the absence of comprehensive health policies are the main factors causing people living in these countries not having access to genetic services. In this article, the authors took benefit from their professional experience of practicing medical genetics in the area and reviewed existing literature to provide their opinions. Particularly, it reviews the current knowledge of genetic disorders' burden and their causative factors in Bangladesh. It focuses on why providing genetic services is challenging in the context of the country's cultural and religious sentiment. Finally, it proposes a physician-academician collaborative framework within the existing facility that aims to tackle the challenges. Such a framework could also be useful for other LICs and LMICs to address the challenges associated with providing genetic services.