The worldwide molecular spectrum and distribution of thalassaemia: a systematic review

Abstract

Context

Thalassaemia is one of the most common inherited autosomal recessive disorders around the world. A considerable amount of literature has been published about the type of mutations and the prevalence of thalassaemia, but findings are often contradictory.

Objective

This systematic review aimed to provide a comprehensive view of the prevalence of thalassaemia-associated mutations in different countries, their effect on haemoglobin (Hb) levels, as well as reporting thalassaemia-associated rare mutations.

Methods

A systematic search of the literature was carried out through major indexing databases (MEDLINE/PubMed, Scopus, EMBASE, Cochrane central, and ISI web of science) using keywords: “Co-inheritance, αα, β, thalassaemia” and “α-β thalassaemia, Mediterranean anemia, mutations” from 1998-September 2019. Hand-searching was also performed. There was no language restriction.

Results

The initial searches yielded 1059 studies, of which 92 articles were included following inclusion and exclusion criteria. Of these, 3.3% (3) of articles were cohort studies, and 96.7% (89) of the remaining articles were cross-sectional studies. Our findings showed that 45.6% (42) of researchers investigated β-thalassaemia, 22.9% (21) αα-β thalassaemia, and 31.5% (29) α thalassaemia.

Conclusion

The present study provides valuable information about the spectrum of thalassaemia-associated mutations, which can be useful for preventing thalassaemia, reducing costs of care, reducing the treatment-related side effects, and showing the most defective mutations.

Highlight

• Evaluating the increase or decrease in the birth prevalence of thalassaemia

• Identifying the most common and rare mutations in various parts of the world

• Comparing researchers' findings from various parts of the world

Keywords:

• Co-inheritance
• α-thalassaemia
• β-thalassaemia
• mutations

Acknowledgements

We wish to thank all our colleagues in Allied Health Sciences School, Ahvaz Jundishapur University of Medical Sciences.

Ethical approval

This article was approved by the sponsor and the applicant concerning scientific content and compliance with applicable research and human subjects' ethical regulations. For this type of study, informed consent is not required.

Author contributions

F.R conceived the manuscript and revised it. M.A and J.M.A wrote the manuscript and prepared tables and figures.

Disclosure statement

No potential conflict of interest was reported by the author(s).