Evaluation of Apolipoprotein e4 allele as Susceptible Factor for Neurodegenerative Diseases among Eastern Indians

Abstract

Background & Objectives: Apolipoprotein E (ApoE) and age have been identified as the major risk factors for several neurodegenerative disorders. Among the three major isoforms (ApoE2, ApoE3 & ApoE4) of APOE, ApoE4 often shows ethnicity dependent association with neurodegenerative diseases. In the present study, we aim to determine the e4 allele/genotype frequency among the different neurodegenerative disorders and their correlation with several demographic and clinical parameters from eastern India. Methods: A total of 826 individuals were recruited for this study which includes 128 PD-MCI, 144 PDD, 90 DLB, 114 FTD, 94 AD and 256 unrelated neurologically controls from eastern India. Subjects were analysed for APOE genotype (E2, E3 and E4) by PCR-RFLP techniques and Sanger sequencing. Results: The APOE4 allele was significantly associated with each of the disease subtypes, selected for the study (P=0.016 to 0.000), while e3 allele was predominant among controls. Further stratification of subjects identified significant overrepresentation of (a) positive family history for FTD (P=0.0414) & AD (P=0.029) and (b) early age at onset of for PDD (P=0.0316) and FTD (P=0.0034) among the e4 allele carriers. Furthermore, lowering of BMSE score was also observed among the e4 allele carriers of AD subjects (P=0.0324). Conclusion: There is a significant association of APOE4 allele with different neurodegenerative diseases influencing lowering of age at onset, BMSE score and positive family history among ethnic Bengali population of eastern India.