Recent studies have identified the rs75932628 (R47H) variant in TREM2 as an 
Alzheimer's disease risk factor with estimated odds ratio ranging from 2.9 to 
5.1. The Cache County Memory Study is a large, population-based sample designed 
for the study of memory and aging. We genotyped R47H in 2974 samples (427 cases 
and 2540 control subjects) from the Cache County study using a custom TaqMan 
assay. We observed 7 heterozygous cases and 12 heterozygous control subjects 
with an odds ratio of 3.5 (95% confidence interval, 1.3-8.8; p = 0.0076). The 
minor allele frequency and population attributable fraction for R47H were 0.0029 
and 0.004, respectively. This study replicates the association between R47H and 
Alzheimer's disease risk in a large, population-based sample, and estimates the 
population frequency and attributable risk of this rare variant.