Serum Apo Lipoprotein E, Apo Lipoprotein E Gene Polymorphisms, and Parkinson's Disease

Background: A central role for apolipoprotein E (APOE) has been suggested in modulating processes of neurodegeneration.

Objective: To study the association between serum APOE levels, APOE gene polymorphisms, and Parkinson's disease (PD).

Material and methods: Fifty-five patients with PD and 30 healthy subjects were enrolled. PD patients were assessed using the Unified Parkinson's Disease Rating Scale (UPDRS), Modified Hoehn and Yahr scale, and Schwab-England Activities of Daily Living scale. Serum APOE level and genotyping for APOE polymorphisms were done for PD patients and controls using enzyme-linked immunosorbent assay and polymerase chain reaction, respectively.

Results: Mean serum APOE level was significantly higher in PD patients compared with healthy controls. APOE ε2/4 genotype was present in a significantly higher proportion of patients compared with controls. APOE ε4 allele was significantly associated with a higher score on the "mentation, behavior, and mood section" of UPDRS compared with ε2 allele. APOE ε2 allele was significantly associated with a shorter disease duration compared with ε3 and ε4 alleles. Mean serum APOE level was significantly higher in patients presenting predominantly by rigidity and bradykinesia compared with those presenting predominantly by tremors. Serum APOE level was positively correlated with mean scores of "mentation, behavior, and mood section" of UPDRS and disease duration. Serum APOE level was a significant predictor for the scores of "mentation, behavior, and mood section" of UPDRS.

Conclusion: APOE ε2/4 genotype might be a susceptibility variant for PD. There may be a possible role for APOE in modulating the process of neurodegeneration in PD.