Jesen Fagerness

Variation in complement factor 3 is associated with risk of age-related macular degeneration

The association of variants in complement factors H and B with age-related macular degeneration has led to more intense genetic and functional analysis of the complement pathway. We identify a nonsynonymous coding change in complement factor 3 that is strongly associated with risk of age-related macular degeneration in a large case-control sample.

Genetic variants near TIMP3 and high-density lipoprotein–associated loci influence susceptibility to age-related macular degeneration

We executed a genome-wide association scan for age-related macular degeneration (AMD) in 2,157 cases and 1,150 controls. Our results validate AMD susceptibility loci near CFH (P < 10−75), ARMS2 (P < 10−59), C2/CFB (P < 10−20), C3 (P < 10−9), and CFI (P < 10−6). We compared our top findings with the Tufts/Massachusetts General Hospital genome-wide association study of advanced AMD (821 cases, 1,709 controls) and genotyped 30 promising markers in additional individuals (up to 7,749 cases and 4,625 controls). With these data, we identified a susceptibility locus near TIMP3 (overall P = 1.1 × 10−11), a metalloproteinase involved in degradation of the extracellular matrix and previously implicated in early-onset maculopathy. In addition, our data revealed strong association signals with alleles at two loci (LIPC, P = 1.3 × 10−7; CETP, P = 7.4 × 10−7) that were previously associated with high-density lipoprotein cholesterol (HDL-c) levels in blood. Consistent with the hypothesis that HDL metabolism is associated with AMD pathogenesis, we also observed association with AMD of HDL-c—associated alleles near LPL (P = 3.0 × 10−3) and ABCA1 (P = 5.6 × 10−4). Multilocus analysis including all susceptibility loci showed that 329 of 331 individuals (99%) with the highest-risk genotypes were cases, and 85% of these had advanced AMD. Our studies extend the catalog of AMD associated loci, help identify individuals at high risk of disease, and provide clues about underlying cellular pathways that should eventually lead to new therapies.

Genome-wide association study of advanced age-related macular degeneration identifies a role of the hepatic lipase gene (LIPC)

Advanced age-related macular degeneration (AMD) is the leading cause of late onset blindness. We present results of a genome-wide association study of 979 advanced AMD cases and 1,709 controls using the Affymetrix 6.0 platform with replication in seven additional cohorts (totaling 5,789 unrelated cases and 4,234 unrelated controls). We also present a comprehensive analysis of copy-number variations and polymorphisms for AMD. Our discovery data implicated the association between AMD and a variant in the hepatic lipase gene (LIPC) in the high-density lipoprotein cholesterol (HDL) pathway (discovery P = 4.53e-05 for rs493258). Our LIPC association was strongest for a functional promoter variant, rs10468017, (P = 1.34e-08), that influences LIPC expression and serum HDL levels with a protective effect of the minor T allele (HDL increasing) for advanced wet and dry AMD. The association we found with LIPC was corroborated by the Michigan/Penn/Mayo genome-wide association study; the locus near the tissue inhibitor of metalloproteinase 3 was corroborated by our replication cohort for rs9621532 with P = 3.71e-09. We observed weaker associations with other HDL loci (ABCA1, P = 9.73e-04; cholesterylester transfer protein, P = 1.41e-03; FADS1-3, P = 2.69e-02). Based on a lack of consistent association between HDL increasing alleles and AMD risk, the LIPC association may not be the result of an effect on HDL levels, but it could represent a pleiotropic effect of the same functional component. Results implicate different biologic pathways than previously reported and provide new avenues for prevention and treatment of AMD.

Variation near complement factor I is associated with risk of advanced AMD

A case–control association study for advanced age-related macular degeneration was conducted to explore several regions of interest identified by linkage. This analysis identified a single nucleotide polymorphism just 3′ of complement factor I on chromosome 4 showing significant association (P<10−7). Sequencing was performed on coding exons in linkage disequilibrium with the detected association. No obvious functional variation was discovered that could be the proximate cause of the association, suggesting a noncoding regulatory mechanism.

Prediction Model for Prevalence and Incidence of Advanced Age-Related Macular Degeneration Based on Genetic, Demographic, and Environmental Variables

PURPOSE The joint effects of genetic, ocular, and environmental variables were evaluated and predictive models for prevalence and incidence of AMD were assessed. METHODS Participants in the multicenter Age-Related Eye Disease Study (AREDS) were included in a prospective evaluation of 1446 individuals, of which 279 progressed to advanced AMD (geographic atrophy or neovascular disease) and 1167 did not progress during 6.3 years of follow-up. For prevalent AMD, 509 advanced cases were compared with 222 controls. Covariates for the incidence analysis included age, sex, education, smoking, body mass index (BMI), baseline AMD grade, and the AREDS vitamin-mineral treatment assignment. DNA specimens were evaluated for six variants in five genes related to AMD. Unconditional logistic regression analyses were performed for prevalent and incident advanced AMD. An algorithm was developed and receiver operating characteristic curves and C statistics were calculated to assess the predictive ability of risk scores to discriminate progressors from nonprogressors. RESULTS All genetic polymorphisms were independently related to prevalence of advanced AMD, controlling for genetic factors, smoking, BMI, and AREDS treatment. Multivariate odds ratios (ORs) were 3.5 (95% confidence interval [CI], 1.7-7.1) for CFH Y402H; 3.7 (95% CI, 1.6-8.4) for CFH rs1410996; 25.4 (95% CI, 8.6-75.1) for LOC387715 A69S (ARMS2); 0.3 (95% CI, 0.1-0.7) for C2 E318D; 0.3 (95% CI, 0.1-0.5) for CFB; and 3.6 (95% CI, 1.4-9.4) for C3 R102G, comparing the homozygous risk/protective genotypes to the referent genotypes. For incident AMD, all these variants except CFB were significantly related to progression to advanced AMD, after controlling for baseline AMD grade and other factors, with ORs from 1.8 to 4.0 for presence of two risk alleles and 0.4 for the protective allele. An interaction was seen between CFH402H and treatment, after controlling for all genotypes. Smoking was independently related to AMD, with a multiplicative joint effect with genotype on AMD risk. The C statistic for the full model with all variables was 0.831 for progression to advanced AMD. CONCLUSIONS Factors reflective of nature and nurture are independently related to prevalence and incidence of advanced AMD, with excellent predictive power.

Common Variants near FRK/COL10A1 and VEGFA are Associated with Advanced Age-related Macular Degeneration

Despite significant progress in the identification of genetic loci for age-related macular degeneration (AMD), not all of the heritability has been explained. To identify variants which contribute to the remaining genetic susceptibility, we performed the largest meta-analysis of genome-wide association studies to date for advanced AMD. We imputed 6 036 699 single-nucleotide polymorphisms with the 1000 Genomes Project reference genotypes on 2594 cases and 4134 controls with follow-up replication of top signals in 5640 cases and 52 174 controls. We identified two new common susceptibility alleles, rs1999930 on 6q21-q22.3 near FRK/COL10A1 [odds ratio (OR) 0.87; P = 1.1 × 10−8] and rs4711751 on 6p12 near VEGFA (OR 1.15; P = 8.7 × 10−9). In addition to the two novel loci, 10 previously reported loci in ARMS2/HTRA1 (rs10490924), CFH (rs1061170, and rs1410996), CFB (rs641153), C3 (rs2230199), C2 (rs9332739), CFI (rs10033900), LIPC (rs10468017), TIMP3 (rs9621532) and CETP (rs3764261) were confirmed with genome-wide significant signals in this large study. Loci in the recently reported genes ABCA1 and COL8A1 were also detected with suggestive evidence of association with advanced AMD. The novel variants identified in this study suggest that angiogenesis (VEGFA) and extracellular collagen matrix (FRK/COL10A1) pathways contribute to the development of advanced AMD.

Association of the SLC1A1 glutamate transporter gene and obsessive‐compulsive disorder

Context: Obsessive‐Compulsive Disorder (OCD) is a debilitating illness with putative glutamatergic abnormalities. Two separate proximal haplotypes in the glutamate transporter gene, SLC1A1, were recently reported to be associated with OCD among males, but replication is required. Objectives: This study examines SLC1A1 as a candidate gene for OCD and explores gender influences. It was hypothesized that a significant association between SLC1A1 and OCD would be replicated in an independent sample of males but not females. Design: Family‐based association candidate gene study. Setting: Participants were recruited from tertiary care OCD specialty clinics. Participants: OCD probands and their first degree relatives. Main outcomes measures: Association of OCD with genotypes of single nucleotide polymorphism (SNP) markers and related haplotypes. Results: Association between OCD and the three‐marker haplotype rs12682807/ rs2072657/ rs301430, with overtransmission of A/T/T, was observed in both genders combined (global P = 0.0015) and in males (global P = 0.0031). Single‐marker associations with OCD in the region (rs3780412 and rs2228622) demonstrated modest significance (permuted P = 0.045). Conclusions: This study identifies a significant association between the SLC1A1 glutamate transporter gene and OCD in a haplotype overlapping with that recently reported.

The corticotropin-releasing hormone gene and behavioral inhibition in children at risk for panic disorder.

BACKGROUND Behavioral inhibition to the unfamiliar (BI) is a heritable temperamental phenotype involving the tendency to display fearful, avoidant, or shy behavior in novel situations. BI is a familial and developmental risk factor for panic and phobic anxiety disorders. We previously observed an association between BI and a microsatellite marker linked to the corticotropin releasing hormone (CRH) gene in children at risk for panic disorder. To evaluate this further, we genotyped additional families for this marker and a panel of markers encompassing the CRH locus. METHODS Sixty-two families that included parents with panic disorder and children who underwent laboratory-based behavioral observations were studied. Family-based association tests and haplotype analysis were used to evaluate the association between BI and polymorphisms spanning the CRH locus. RESULTS We examined a set of markers which we found to reside in a block of strong linkage disequilibrium encompassing the CRH locus. The BI phenotype was associated with the microsatellite marker (p=.0016) and three single nucleotide polymorphisms (SNPs), including a SNP in the coding sequence of the gene (p=.023). Haplotype-specific tests revealed association with a haplotype comprising all of the markers (p=.015). CONCLUSIONS These results suggest that the CRH gene influences inhibited temperament, a risk factor for panic and phobic anxiety disorders. Genetic studies of anxiety-related temperament represent an important strategy for identifying the genetic basis of anxiety disorders.

Influence of RGS2 on Anxiety-Related Temperament, Personality, and Brain Function

CONTEXT Although anxiety disorders are heritable, their genetic and phenotypic complexity has made the identification of susceptibility genes difficult. Well-validated animal models and intermediate phenotypes provide crucial tools for genetic dissection of anxiety. The gene encoding regulator of G protein signaling 2 (Rgs2) is a quantitative trait gene that influences mouse anxiety behavior, making its human ortholog (RGS2) a compelling candidate gene for human anxiety phenotypes. OBJECTIVE To examine whether variation in RGS2 is associated with intermediate phenotypes for human anxiety disorders. DESIGN Family-based and case-control association analysis of single-nucleotide polymorphisms at the RGS2 locus in 3 independent samples. SETTING Massachusetts General Hospital, University of California, San Diego, and San Diego State University. PARTICIPANTS Study participants included a family-based sample (n = 119 families) of children who underwent laboratory-based assessments of temperament (behavioral inhibition), a sample of 744 unrelated adults who completed assessments of extraversion and introversion, and 55 unrelated adults who underwent functional magnetic resonance imaging measures of response to emotional faces. MAIN OUTCOME MEASURES Laboratory-based behavioral measures of childhood temperament, self-report measure of personality, and functional magnetic resonance imaging response to emotion processing. RESULTS Markers spanning RGS2 were associated with childhood behavioral inhibition, a temperamental precursor of social anxiety disorder (haplotype P = 3 x 10(-5); odds ratio, 2.99 in complete trios). In independent samples, RGS2 markers, including rs4606, which has previously been associated with RGS2 expression, were also associated with introversion (a core personality trait in social anxiety disorder) and with increased limbic activation (insular cortex and amygdala) during emotion processing (brain phenotypes correlated with social anxiety). The genotype at rs4606 explained 10% to 15% of the variance in amygdala and insular cortex activation to emotional faces. CONCLUSIONS These results provide the first evidence that a gene that influences anxiety in mice is associated with intermediate phenotypes for human anxiety disorders across multiple levels of assessment, including childhood temperament, adult personality, and brain function. This translational research suggests that some genetic influences on anxiety are evolutionarily conserved and that pharmacologic modulation of RGS2 function may provide a novel therapeutic approach for anxiety disorders.

Genome-wide association study of Tourette's syndrome

Tourettes syndrome (TS) is a developmental disorder that has one of the highest familial recurrence rates among neuropsychiatric diseases with complex inheritance. However, the identification of definitive TS susceptibility genes remains elusive. Here, we report the first genome-wide association study (GWAS) of TS in 1285 cases and 4964 ancestry-matched controls of European ancestry, including two European-derived population isolates, Ashkenazi Jews from North America and Israel and French Canadians from Quebec, Canada. In a primary meta-analysis of GWAS data from these European ancestry samples, no markers achieved a genome-wide threshold of significance (P<5 × 10−8); the top signal was found in rs7868992 on chromosome 9q32 within COL27A1 (P=1.85 × 10−6). A secondary analysis including an additional 211 cases and 285 controls from two closely related Latin American population isolates from the Central Valley of Costa Rica and Antioquia, Colombia also identified rs7868992 as the top signal (P=3.6 × 10−7 for the combined sample of 1496 cases and 5249 controls following imputation with 1000 Genomes data). This study lays the groundwork for the eventual identification of common TS susceptibility variants in larger cohorts and helps to provide a more complete understanding of the full genetic architecture of this disorder.