Effect of APOE polymorphisms on early responses to traumatic brain injury

To investigate the relationship between apolipoprotein E (APOE) polymorphisms and the severity of traumatic brain injury (TBI) in acute stage in the cohort of mainland Chinese patients. We prospectively identified admissions to the two neurosurgical departments for head injury. A total of 110 subjects with TBI (80 males and 30 females, with mean age of 43.87 years) were enrolled from December 2003 to May 2004, and demographic and clinical data were collected. Venous blood was collected from patients with TBI on admission to determine the APOE genotype polymorphisms. The APOE genotyping was performed by means of PCR-RFLP. The deterioration of patients' condition in acute stage (<7 days after TBI) was judged by either of following criteria: decrease of GCS, increase in hematoma volume or delayed hematoma both detected by repeated CT scanning. Chi2-test and logistic regression analyses were done by SPSS. The distributions of APOE genotypes and alleles matched Hardy-Weinberg law. In 110 Chinese patients, 19 subjects presented with deteriorated clinical condition after hospitalization, and seven of 17 patients with APOE epsilon4 (41.2%) had a deteriorated condition which was significantly different from those without APOE epsilon4 (12 of 93 patients, 12.9%, P=0.01). However, neither the presence of epsilon2 nor of epsilon3 was significantly different from those absent of it (P>0.05). Logistic regression analyses showed that APOE epsilon4 was a risk factor (OR=4.836, P=0.011, 95% CI 1.443-16.208) to predispose to clinical deterioration after adjusting for patient age, sex, smoking or not, alcohol-drinking or not, injury severity, injury mechanisms, treatments, and pattern of TBI. This finding suggests that the patients with APOE epsilon4 predispose to clinical deterioration in acute phase after TBI and APOE polymorphisms play a role in early responses to TBI.