Project description:ObjectiveTo evaluate for racial differences in triggering receptor expressed on myeloid cells 2 (TREM2), a key immune mediator in Alzheimer disease, the levels of CSF soluble TREM2 (sTREM2), and the frequency of associated genetic variants were compared in groups of individuals who self-reported their race as African American (AA) or non-Hispanic White (NHW).MethodsCommunity-dwelling older research participants underwent measurement of CSF sTREM2 concentrations and genetic analyses.ResultsThe primary cohort included 91 AAs and 868 NHWs. CSF sTREM2 levels were lower in the AA compared with the NHW group (1,336 ± 470 vs 1,856 ± 624 pg/mL, p < 0.0001). AAs were more likely to carry TREM2 coding variants (15% vs 3%, p < 0.0001), which were associated with lower CSF sTREM2. AAs were less likely to carry the rs1582763 minor allele (8% vs 37%, p < 0.0001), located near MS4A4A, which was associated with higher CSF sTREM2. These findings were replicated in an independent cohort of 23 AAs and 917 NHWs: CSF sTREM2 levels were lower in the AA group (p = 0.03), AAs were more likely to carry coding TREM2 variants (22% vs 4%, p = 0.002), and AAs were less likely to carry the rs1582763 minor allele (16% vs 37%, p = 0.003).ConclusionsOn average, AAs had lower CSF sTREM2 levels compared with NHWs, potentially because AAs are more likely to carry genetic variants associated with lower CSF sTREM2 levels. Importantly, CSF sTREM2 reflects TREM2-mediated microglial activity, a critical step in the immune response to amyloid plaques. These findings suggest that race may be associated with risk for genetic variants that influence Alzheimer disease-related inflammation.
Project description:BackgroundTREM2 encodes for triggering receptor expressed on myeloid cells 2 and has rare, coding variants that associate with risk for late-onset Alzheimer's disease (LOAD) in Caucasians of European and North-American origin. This study evaluated the role of TREM2 in LOAD risk in African-American (AA) subjects. We performed exonic sequencing and validation in two independent cohorts of >800 subjects. We selected six coding variants (p.R47H, p.R62H, p.D87N, p.E151K, p.W191X, and p.L211P) for case-control analyses in a total of 906 LOAD cases vs. 2,487 controls.ResultsWe identified significant LOAD risk association with p.L211P (p=0.01, OR=1.27, 95%CI=1.05-1.54) and suggestive association with p.W191X (p=0.08, OR=1.35, 95%CI=0.97-1.87). Conditional analysis suggests that p.L211P, which is in linkage disequilibrium with p.W191X, may be the stronger variant of the two, but does not rule out independent contribution of the latter. TREM2 p.L211P resides within the cytoplasmic domain and p.W191X is a stop-gain mutation within the shorter TREM-2V transcript. The coding variants within the extracellular domain of TREM2 previously shown to confer LOAD risk in Caucasians were extremely rare in our AA cohort and did not associate with LOAD risk.ConclusionsOur findings suggest that TREM2 coding variants also confer LOAD risk in AA, but implicate variants within different regions of the gene than those identified for Caucasian subjects. These results underscore the importance of investigating different ethnic populations for disease risk variant discovery, which may uncover allelic heterogeneity with potentially diverse mechanisms of action.
Project description:Objective: To explore cerebrospinal fluid (CSF) levels of soluble triggering receptor expressed on myeloid cells 2 (sTREM2) and neurofilament light proteins (NFL) in patients with neurosyphilis (NS). Methods: We enrolled 71 NS patients (41 early-NS and 30 late-NS patients) and 20 syphilis but non-NS patients whose CSF samples were collected. The CSF levels of the microglial activation biomarker sTREM2 and neuronal injury biomarker NFL were measured using ELISA. Results: CSF sTREM2 levels were significantly higher in NS patients compared to those in syphilis/non-NS patients (p < 0.001). In a subgroup analysis, the CSF sTREM2 levels elevated significantly in late-NS patients than those in early-NS patients (p < 0.001). The CSF sTREM2 levels in early-NS group were also significantly higher than those in syphilis/non-NS group (p = 0.024). Like CSF sTREM2, similar differences between groups were also found in CSF NFL. There was a moderate correlation between CSF sTREM2 and CSF NFL (r = 0.406, p < 0.001) in NS group. Conclusions: CSF sTREM2 levels elevated in NS and peaked at the late stage, suggesting that CSF sTREM2 may be a useful marker to quantify microglia activation in NS and may play a role in the progression of NS. The positive correlation between CSF sTREM2 and CSF NFL indicates a linkage between microglial activation and neuronal injury in NS.
Project description:ObjectivesTo assess the association of established multiple sclerosis (MS) risk variants in 3,254 African Americans (1,162 cases and 2,092 controls).MethodsHuman leukocyte antigen (HLA)-DRB1, HLA-DQB1, and HLA-A alleles were typed by molecular techniques. Single nucleotide polymorphism (SNP) genotyping was conducted for 76 MS-associated SNPs and 52 ancestry informative marker SNPs selected throughout the genome. Self-declared ancestry was refined by principal component analysis of the ancestry informative marker SNPs. An ancestry-adjusted multivariate model was applied to assess genetic associations.ResultsThe following major histocompatibility complex risk alleles were replicated: HLA-DRB1*15:01 (odds ratio [OR] = 2.02 [95% confidence interval: 1.54-2.63], p = 2.50e-07), HLA-DRB1*03:01 (OR = 1.58 [1.29-1.94], p = 1.11e-05), as well as HLA-DRB1*04:05 (OR = 2.35 [1.26-4.37], p = 0.007) and the African-specific risk allele of HLA-DRB1*15:03 (OR = 1.26 [1.05-1.51], p = 0.012). The protective association of HLA-A*02:01 was confirmed (OR = 0.72 [0.55-0.93], p = 0.013). None of the HLA-DQB1 alleles were associated with MS. Using a significance threshold of p < 0.01, outside the major histocompatibility complex region, 8 MS SNPs were also found to be associated with MS in African Americans.ConclusionMS genetic risk in African Americans only partially overlaps with that of Europeans and could explain the difference of MS prevalence between populations.
Project description:Thyroid stimulating hormone (TSH) hormone levels are normally tightly regulated within an individual; thus, relatively small variations may indicate thyroid disease. Genome-wide association studies (GWAS) have identified variants in PDE8B and FOXE1 that are associated with TSH levels. However, prior studies lacked racial/ethnic diversity, limiting the generalization of these findings to individuals of non-European ethnicities. The Electronic Medical Records and Genomics (eMERGE) Network is a collaboration across institutions with biobanks linked to electronic medical records (EMRs). The eMERGE Network uses EMR-derived phenotypes to perform GWAS in diverse populations for a variety of phenotypes. In this report, we identified serum TSH levels from 4,501 European American and 351 African American euthyroid individuals in the eMERGE Network with existing GWAS data. Tests of association were performed using linear regression and adjusted for age, sex, body mass index (BMI), and principal components, assuming an additive genetic model. Our results replicate the known association of PDE8B with serum TSH levels in European Americans (rs2046045 p = 1.85×10-17, β = 0.09). FOXE1 variants, associated with hypothyroidism, were not genome-wide significant (rs10759944: p = 1.08×10-6, β = -0.05). No SNPs reached genome-wide significance in African Americans. However, multiple known associations with TSH levels in European ancestry were nominally significant in African Americans, including PDE8B (rs2046045 p = 0.03, β = -0.09), VEGFA (rs11755845 p = 0.01, β = -0.13), and NFIA (rs334699 p = 1.50×10-3, β = -0.17). We found little evidence that SNPs previously associated with other thyroid-related disorders were associated with serum TSH levels in this study. These results support the previously reported association between PDE8B and serum TSH levels in European Americans and emphasize the need for additional genetic studies in more diverse populations.
Project description:Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease and affects 1% of the population above 60 years old. Although Parkinson's disease commonly manifests with motor symptoms, a majority of patients with Parkinson's disease subsequently develop cognitive impairment, which often progresses to dementia, a major cause of morbidity and disability. Parkinson's disease is characterized by α-synuclein accumulation that frequently associates with amyloid-β and tau fibrils, the hallmarks of Alzheimer's disease neuropathological changes; this co-occurrence suggests that onset of cognitive decline in Parkinson's disease may be associated with appearance of pathological amyloid-β and/or tau. Recent studies have highlighted the appearance of the soluble form of the triggering receptor expressed on myeloid cells 2 (sTREM2) receptor in CSF during development of Alzheimer's disease. Given the known association of microglial activation with advancing Parkinson's disease, we investigated whether CSF and/or plasma sTREM2 differed between CSF biomarker-defined Parkinson's disease participant subgroups. In this cross-sectional study, we examined 165 participants consisting of 17 cognitively normal elderly subjects, 45 patients with Parkinson's disease with no cognitive impairment, 86 with mild cognitive impairment, and 17 with dementia. Stratification of subjects by CSF amyloid-β and tau levels revealed that CSF sTREM2 concentrations were elevated in Parkinson's disease subgroups with a positive tau CSF biomarker signature, but not in Parkinson's disease subgroups with a positive CSF amyloid-β biomarker signature. These findings indicate that CSF sTREM2 could serve as a surrogate immune biomarker of neuronal injury in Parkinson's disease.
Project description:IntroductionBlack/white disparities in lung cancer incidence and mortality mandate an evaluation of underlying biological differences. We have previously shown higher risks of lung cancer associated with prior emphysema in African American compared with white patients with lung cancer.MethodsWe therefore evaluated a panel of 1440 inflammatory gene variants in a two-phase analysis (discovery and replication), added top genome-wide association studies (GWAS) lung cancer hits from white populations, and 28 single-nucleotide polymorphisms (SNPs) from a published gene panel. The discovery set (477 self-designated African Americans cases, 366 controls matched on age, ethnicity, and gender) were from Houston, Texas. The external replication set (330 cases and 342 controls) was from the EXHALE study at Wayne State University.ResultsIn discovery, 154 inflammation SNPs were significant (p < 0.05) on univariate analysis, as was one of the gene panel SNPs (rs308738 in REV1, p = 0.0013), and three GWAS hits, rs16969968 p = 0.0014 and rs10519203 p = 0.0003 in the 15q locus and rs2736100, in the HTERT locus, p = 0.0002. One inflammation SNP, rs950286, was successfully replicated with a concordant odds ratio of 1.46 (1.14-1.87) in discovery, 1.37 (1.05-1.77) in replication, and a combined odds ratio of 1.40 (1.17-1.68). This SNP is intergenic between IRF4 and EXOC2 genes. We also constructed and validated epidemiologic and extended risk prediction models. The area under the curve (AUC) for the epidemiologic discovery model was 0.77 and 0.80 for the extended model. For the combined datasets, the AUC values were 0.75 and 0.76, respectively.ConclusionsAs has been reported for other cancer sites and populations, incorporating top genetic hits into risk prediction models, provides little improvement in model performance and no clinical relevance.
Project description:TREM2 was suggested to be an important regulator of microglia during neurodegeneration, but previous studies report conflicting results in relation to soluble TREM2 (sTREM2) in cerebrospinal fluid (CSF) when using clinical criteria to classify Alzheimer's disease (AD). The present study explores sTREM2 CSF levels and their associations with other biomarkers and cognitive measures in a prospective AD cohort. Based on the available CSF biomarker information, 497 subjects were classified according to the 2018 National Institute on Aging-Alzheimer's Association research framework guidelines, which group biomarkers into those of amyloid-? deposition, tau pathology, and neurodegeneration. CSF sTREM2 concentrations were associated with markers of neurodegeneration and fibrillar tau pathology, but not amyloidosis; sTREM2 concentrations were increased in total tau-positive versus -negative individuals; sTREM2 was not related to cognitive and other biomarker changes over time; and sTREM2 concentrations increased over time in total tau-positive versus -negative individuals with AD pathophysiology. The present study provides evidence in support of sTREM2 in CSF as a marker of neuroinflammation across the spectrum of early clinical AD. sTREM2 is linked to neuronal injury and may therefore offer complementary information relevant for diagnostic purposes and novel treatment approaches targeting the immune system in AD.