Associations between Apolipoprotein E(APOE) polymorphisms and Cerebral Palsy: a meta-analysis

Background Apolipoprotein E (APOE ) is one of the main apolipoproteins playing important roles in the central neuronal system. The relationship between polymorphisms and cerebral palsy (CP) is contradictory.Methods The overall experimental studies of APOE polymorphisms and CP risk were researched. We conducted eligible studies identified from Elsevier Science Direct, PubMed, Springer Link, WEB OF SCIENCE, Chinese National Knowledge Infrastructure and WanFang Data up to February 2019 to make a systematic review.Results Totally 10 eligible studies were used to meta-analysis (1570 CP cases and 1982 subjects). Significant associations with CP were observed for APOE polymorphisms in allele (ε4: P < 0.001, OR 2.05, 95% CI 1.40 to 2.99; ε2: P = 0.04, OR 1.41, 95% CI 1.01 to 1.96) and dominant (E4 carriers: P = 0.004, OR 1.90, 95% CI 1.23 to 2.92) models in overall analyses. Interestingly, subgroup analysis indicated a significant increased risk for CP in Chinese patients of CP with APOE ε4 (P<0.00001, OR 3.71, 95% CI 2.37 to 5.78) and E4 carriers(P<0.00001, OR 3.95, 95% CI 2.38 to 6.53), but not with APOE ε2 (P=0.69, OR 1.09, 95% CI 0.72 to 1.65).Conclusions Combined with the results of our analysis, we concluded that the risk of CP was significantly increased in ε4 individuals. But meta-analysis yielded an incongruent result for the APOE ε2 allele between in multi-ethnic samples and in Chinese subgroup. These conclusions should be confirmed through further studies.