LARP2 DNA Methylation in Transfusion-dependent Haemoglobin E-Beta (HbE/β) and β-Thalassaemia Major Patients

ABSTRACT

Abstract@#Introduction: The large clinical spectrum of haemoglobin E-beta (HbE/β) thalassaemia leads to the investigation of complex mechanisms involved in erythropoiesis. DNA methylation in LARP2 is one of the potential epigenetic modifiers not fully explored in HbE/β and β-thalassaemia major. This study aimed to analyse DNA methylation profile and gene expression of LARP2 using peripheral blood (PB) in nucleated red blood cells (NRBCs) for the source of DNA of HbE/β- and β-thalassaemia major patients. Methods: PB were collected from 33 transfusion-dependent thalassemia patients from Hospital USM and Hospital RPZII, Kelantan, Malaysia. DNA methylation profile and gene expression of LARP2 were examined by bisulphite sequencing PCR and quantitative real-time PCR respectively. Results: Partial DNA methylation of LARP2 was observed in 43% (9/21) HbE/β- and 17% (2/12) β-thalassaemia major patients. LARP2 expression (1.49±26.60) in HbE/β-thalassaemia was not significant against normal controls and β-thalassaemia major (p>0.05). In contrast, LARP2 expression (6.8±16.42) in β-thalassaemia major showed a significant up-regulation against normal controls (p<0.05). The association of LARP2 expression and DNA methylation profile was statistically significant (p<0.001). LARP2 expression was down-regulated in 75% (3/4) HbE/β-thalassaemia patients with CD26/IVS1-5, in contrast to up-regulation of 80% (4/5) IVS1-5/IVS1-5 β-thalassaemia major patients. DNA methylation of LARP2 in these patients were either partially methylated or unmethylated in CD26/IVS1-5 and IVS15/IVS1-5 respectively. Conclusion: DNA methylation of LARP2 may act as an additional modifier to gene mutation especially involving IVS1-5 in HbE/β-thalassaemia. Homozygous IVS1-5 in β-thalassaemia major may contribute to different disease presentation compared to those involving CD26 in HbE/β-thalassaemia.