Negative results Triggering receptor expressed on myeloid cells 2 variant is rare in late-onset Alzheimer’s disease in Han Chinese individuals Jin-Tai Yu a, b, c, ** , Teng Jiang a , Ying-Li Wang b , Hui-Fu Wang b , Wei Zhang b , Nan Hu b , Lin Tan b , Lei Sun b , Meng-Shan Tan c , Xi-Chen Zhu a , Lan Tan a, b, c, * a Department of Neurology, Qingdao Municipal Hospital, Nanjing Medical University, Qingdao, China b Department of Neurology, Qingdao Municipal Hospital, School of Medicine, Qingdao University, Qingdao, China c Department of Neurology, Qingdao Municipal Hospital, College of Medicine and Pharmaceutics, Ocean University of China, Qingdao, China article info Article history: Received 29 May 2013 Received in revised form 1 October 2013 Accepted 6 October 2013 Available online 11 October 2013 Keywords: Alzheimer’s disease TREM2 Genetic Mutation Association abstract Recent studies have reported that a rare mutation of triggering receptor expressed on myeloid cells 2 gene (TREM2 [rs75932628-T]) has significantly increased the risk of late-onset Alzhemier’s disease (LOAD) in European-descendent population. To date, no study has investigated the association between rare mutations of TREM2 and LOAD risk in non-European population. Here, we sequenced exon2 of TREM2 in the northern Han Chinese population consisting of 1133 patients with LOAD and 1159 control subjects. Although, 4 novel mutations (c.102G>A: Val34Val, c.330C>T: Cys110Cys, c.342T>C: His114His, and c.343G>A: Gly115Ser) were identified in patients with LOAD, none of them exhibited significant association with LOAD risk after Bonferroni correction. Most importantly, the previously reported rare variants in European-descendent population including rs75932628-T (predicted to cause an R47H sub- stitution) were absent in our cohort. These findings suggest that mutations in exon2 of TREM2 were unlikely to play a key role in the susceptibility of LOAD in the northern Han Chinese population. Ó 2014 Elsevier Inc. All rights reserved. 1. Introduction Recently, 2 independent groups have identified a rare func- tional variant (rs75932628-T, encoding R47H) within the trig- gering receptor expressed on myeloid cells 2 gene (TREM2) that are strongly associated with late-onset Alzheimer’s disease (LOAD) in cohorts from Iceland, Germany, Netherlands, Norway, and USA, with an or similar to that of the apolipoprotein E allele (Guerreiro et al., 2013; Jonsson et al., 2013). Moreover, this finding has been successfully replicated in French and Spanish population (Benitez et al., 2013; Giraldo et al., 2013; Pottier et al., 2013). TREM2 spans 41,126,246-41,130,922 base pairs on chromosome 6p21.1 and encodes a 230 amino acid polypeptide called TREM2, which is a transmembrane glycoprotein that is mainly expressed on osteoclasts and microglia, playing an important role in the regulation of inflammatory responses and phagocytic process (Jiang et al., 2013). To date, no study has investigated the associ- ation between rare mutations of TREM2 and LOAD risk in non-European population. Considering the fact that a dispropor- tionate number of variants were observed in exon2 of TREM2 in patients with LOAD (Guerreiro et al., 2013), we therefore per- formed sequencing to analyze exon2 of TREM2 for rare mutations that related to LOAD risk in a large northern Han Chinese population. 2. Methods The current study comprised 2292 unrelated subjects (1133 patients with LOAD and 1159 healthy control subjects matched for gender and age), who were northern Han Chinese individuals by origin. Genomic DNA was extracted from venous blood using the Wizard Genomic DNA Purification Kit (catalog no. A1125, Promega, Madison, WI) as described previously (Yu et al., 2013). The sequences within exon2 of TREM2 were obtained from the UCSC Genome Browser Database and referred to Human Genome Resources. The primer 3 software was used to design primers. The purified polymerase chain reaction products were sequenced using the BigDye Terminator v3.1 sequencing chemistry from Applied Biosystems (Foster City, CA) and run on ABI3130XL J.T.Y., T.J., Y.L.W. should be regarded as co-first authors. * Corresponding author at: Department of Neurology, Qingdao Municipal Hos- pital, School of Medicine, Qingdao University, No. 5 Donghai Middle Road, Qingdao 266071, PR China. Tel./fax: þ86 532 8890 5659. ** Alternate corresponding author at: Department of Neurology, Qingdao Munic- ipal Hospital, School of Medicine, Qingdao University, No. 5 Donghai Middle Road, Qingdao 266071, PR China. Tel.: þ86 532 8890 5658; fax: þ86 532 8890 5659. E-mail addresses: yu-jintai@163.com (J.-T. Yu), dr.tanlan@163.com (L. Tan). Contents lists available at ScienceDirect Neurobiology of Aging journal homepage: www.elsevier.com/locate/neuaging 0197-4580/$ e see front matter Ó 2014 Elsevier Inc. All rights reserved. http://dx.doi.org/10.1016/j.neurobiolaging.2013.10.075 Neurobiology of Aging 35 (2014) 937.e1e937.e3