HBB Gene Mutations and Their Pathological Impacts on HbE/β-Thalassaemia in Kuala Terengganu, Malaysia

Abstract

Background: β-thalassaemia is a disorder caused by mutations in the β-globin gene, leading to defective production of haemoglobins (Hb) and red blood cells (RBCs). It is characterised by anaemia, ineffective erythropoiesis, and iron overload. Patients with severe β-thalassaemia require lifelong blood transfusions. Haemoglobin E beta-thalassaemia (HbE/β-thalassaemia) is a severe form of β-thalassaemia in Asian countries. More than 200 alleles have been recognised in the β-globin region. Different geographical regions show different frequencies of allelic characteristics. In this study, the spectrum of β-thalassaemia (β-thal) alleles and their correlation with iron overload, in HbE/β-thalassaemia patients, β-thalassaemia trait, and HbE trait were studied. Methods: Blood samples (n = 260) were collected from 65 β-thalassaemia patients, 65 parents (fathers and/or mothers) and 130 healthy control individuals. Haematological analyses, iron profiles, and serum hepcidin levels were examined for all participants. DNA was extracted from patients’ and their parents’ blood samples, then subjected to PCR amplification. Multiplex amplification refractory mutation system PCR (MARMS-PCR) was conducted for eighteen primers to detect the mutations. Results: There was severe anaemia present in HbE/β-thalassaemia patients compared to their parents and healthy controls. The ferritin and iron levels were significantly increased in patients compared to their parents and healthy controls (p = 0.001). Two common mutations were detected among the patient group and three mutations were detected among their parents, in addition to seven novel mutations in HbE/β-thalassaemia patients (explained in results). Conclusion: Some mutations were associated with severe anaemia in β-thalassaemia patients. The detection of mutations is a prognostic marker, and could enhance the appropriate management protocols and improve the haematological and biochemical statuses of β-thalassaemia patients.

Keywords

• β-globin gene mutations
• HbE/β-thalassaemia
• β-thalassaemia trait
• polymerase chain reaction
• MARMS-PCR