Background and Objective: The promoter of the apolipoprotein E (APOE) gene is polymorphic at positions -491A/T, -427C/T and -219G/T. These single nucleotide polymorphisms may alter transcriptional activity and impact APOE expression due to differential binding of transcription factors. It has been suggested that the -491 A, -427 C and -219 T alleles are associated with a high risk of developing Alzheimer’s disease. This study aims to investigate the frequencies of APOE promoter polymorphisms in three major ethnic groups (Malay, Chinese and Indian) in Malaysia. Method: DNA was extracted from blood obtained from 290 healthy people (Malay: n= 92; Chinese: n= 105; and Indian: n= 93), and the promoter region was amplifi ed using PCR and genotyped by direct sequencing. Result: The Indian group has the lowest frequencies of - 491 A, - 427 C and - 219 T alleles (83.9%, 3.2% and 56.5%, respectively) compared to the Chinese group with the highest frequencies (97.1%, 11.9% and 67.1%, respectively). The frequencies in the Malay group were somewhere in between (94.6%, 8.2% and 61.4%, respectively). Moreover, for the - 491 and - 427 positions, the frequencies of possible genotypes viz., AA or AT or TT and CC or CT or TT, respectively, were statistically signifi cant (P < 0.05, Chi- Square Test) between the 3 ethnic groups. Conclusion: Based on the frequency of APOE promoter polymorphisms alone, the ethnic Indian may be predisposed to lower risks for AD than the Chinese or Malay.

The complex pathophysiology of traumatic brain injury, its cascading effects and a varied outcome suggest that factors such as genetics may permeate and modulate the neurocognitive outcomes in patients with mild traumatic brain injury (mTBI). This study was conducted to determine the relationship between genetic polymorphism of apolipoprotein E, and neurocognitive and functional outcomes in mTBI. Twenty-one patients with mTBI were recruited prospectively. The severity of the injury was established with the Glasgow Coma Score (GCS). Other assessments included the CT Scan of the head on admission, Disability Rating Scale, Chessington Occupational Therapy Neurological Assessment (COTNAB) and Glasgow Outcome Scale (GOS). The Spearmen correlation analysis of ApoE allele status and the cognitive and functional assessments saw some association with the Sensory Motor Ability - Coordination (-0.526, p<0.05), Communication Ability (-0.651, p<0.05), and the Employability (Return to Work) at 1st month (0.455, p<0.05). Notably, the deficits of specific attributes of visuospatial and sensory motor function were seen with greater impairment consistently observed in patients with ApoE e4 allele. In conclusion, the preliminary findings support the possible relationship that exists between ApoE e4 and neurocognitive impairment in mTBI, despite good functional recovery in 6 months post injury.