Association Study of the TREM2 Gene and Identification of a Novel Variant in Exon 2 in Iranian Patients with Late-Onset Alzheimer's Disease

OBJECTIVE: To analyze the association between TREM2 exon 2 variants and late-onset (sporadic) Alzheimer's disease (AD) in an elderly Iranian population. MATERIALS AND METHODS: Exon 2 of TREM2 in a total of 131 AD patients and 157 controls was genotyped using polymerase chain reaction and Sanger sequencing. Fisher's exact test was used to compare the allele and genotype frequency between the 2 study groups. RESULTS: One homozygous and 2 heterozygous carriers of rs75932628-T in the AD patients and 1 heterozygous carrier in the control group were identified. One novel damaging variant, G55R, was also detected in the AD patient group. The frequency of rs75932628-T as well as the amount of rare variants were higher in the AD patients than in the controls, but this did not reach a statistically significant association with AD (odds ratio: 4.8; 95% confidence interval: 0.54 to 43.6; p = 0.270). CONCLUSION: The rs75932628-T allele frequency in the elderly Iranian population (0.86%) was high.