A non-synonymous genetic rare variant, rs75932628-T (p.R47H), in the TREM2 gene 
has recently been reported to be a strong genetic risk factor for Alzheimer's 
disease (AD). Also, rare recessive mutations have been associated with 
frontotemporal dementia (FTD). We aimed to investigate the role of p.R47H 
variant in AD and FTD through a multi-center study comprising 3172 AD and 682 
FTD patients and 2169 healthy controls from Spain. We found that 0.6% of AD 
patients carried this variant compared to 0.1% of controls (odds ratio [OR] = 
4.12, 95% confidence interval [CI] = 1.21-14.00, p = 0.014). A meta-analysis 
comprising 32,598 subjects from 4 previous studies demonstrated the large effect 
of the p.R47H variant in AD risk (OR = 4.11, 95% CI = 2.99-5.68, p = 
5.27×10(-18)). We did not find an association between p.R47H and age of onset of 
AD or family history of dementia. Finally, none of the FTD patients harbored 
this genetic variant. These data strongly support the important role of p.R47H 
in AD risk, and suggest that this rare genetic variant is not related to FTD.