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

Abstract

α-Thalassemia (α-thal) is assumed to be very prevalent in Bangladesh. We aimed to assess the prevalence of the disease in the country and provide a model for α-thal newborn screening in Bangladesh. We collected umbilical cord blood (UCB) samples from 413 unrelated newborns in Bangladesh. Demographic information, blood indices, osmotic fragility, serum iron (Fe), and zinc (Zn) levels were evaluated for all the subjects. All subjects underwent a polymerase chain reaction (PCR)-based diagnosis for α-thal status, followed by a multiplex gap-PCR-based identification of the deletion type present. Sixty-seven subjects had at least one α-thal deletion (16.22%). We observed that –α^3.7 (rightward), – –^SEA (Southeast Asian), –α^4.2 (leftward), – –^MED (Mediterranean) and – –^THAI (Thailand) deletions were the most common α-globin deletions present in the country, with the –α^3.7 (n = 37) and – –^SEA (n = 18) being most prevalent. The osmotic fragility test (OFT) could predict the presence of α-thal deletions with over 98.0% sensitivity. Complete UCB count analysis revealed significant differences between healthy subjects and subjects with α-thal deletions. Although the iron level was almost the same (108.0 vs. 105.7 µg/dL), a reduced level of Zn (98.6 vs. 71.8 µg/dL, p < 0.01) was observed in the cord blood-derived serum of the subjects with α-thal deletions. Moreover, parental age at the time of delivery, gestational period, and birth weight was lower in the subjects with α-thal deletions. This study provides partial information on the epidemiology of α-thal in Bangladesh and describes a model for α-thal newborn screening in the country.

Keywords:

• α-Thalassemia (α-thal)
• newborn screening (NBS)
• complete umbilical cord blood (UCB) counts
• osmotic fragility test (OFT)
• gap-polymerase chain reaction (gap-PCR)

Acknowledgments

We thank the authorities of the participating hospitals for their kind help during cord blood collection. We also thank Fahad Hasan, Yusha Araf, Dolilur Rahman, Md. Tawfiqur Mannan Khan (undergraduate students, Shahjalal University of Science and Technology, Bangladesh), Soheli Hasan Chhoya (Community Based Medical College and Hospital, Mymensingh, Bangladesh) and Nafisa Tasnim Nusha (graduate student, West Virginia University, Morgantown, WV, USA) for their kind help during the experiments. We wholeheartedly acknowledge the kind cooperation of Dr. Samia Hassan Rizk (Professor, Cairo University, Cairo, Egypt) for helping us with designing the project. All data supporting the findings of this study are available within the article and its supplementary materials. Author contribution: S. Anwar and Md.F. Miah conceived the study; Md.F. Miah acquired the funding; S. Anwar and J.T. Mourosi, investigated the data; S. Anwar, M.J. Hosen oversaw the methodology; S. Anwar and J.T. Mourosi oversaw the software; M.J. Hosen and Md.F. Miah supervised the study; S. Anwar envisioned the project and wrote the original draft; S. Anwar, M.J. Hosen and Md.F. Miah reviewed and edited the manuscript.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

The Research Center (1), and yearly research allocation of the Department of Genetic Engineering and Biotechnology, Shahjalal University of Science and Technology, Sylhet, Bangladesh (2) partially supported this study. The funders had no role in the design and conduct of the study, report writing, and decision to submit the manuscript for publication.