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Raj, Towfique

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Towfique

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Raj, Towfique

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2012 - 20148

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Author's Publications: search.filters.isAuthorOfPublication.29574496-493e-4140-be13-a44f232f201b

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Now showing 1 - 8 of 8
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    Extensive Genetic Diversity and Substructuring Among Zebrafish Strains Revealed through Copy Number Variant Analysis
    (Proceedings of the National Academy of Sciences, 2012) Brown, Kim H.; Dobrinski, Kimberly P.; Lee, Arthur S.; Gokcumen, Omer; Mills, Ryan Edward; Shi, Xinghua; Chong, Wilson W. S.; Chen, Jin Yun Helen; Yoo, Paulo; David, Sthuthi; Peterson, Samuel M.; Raj, Towfique; Choy, Kwong Wai; Stranger, Barbara Elaine; Williamson, Robin E.; Zon, Leonard; Freeman, Jennifer L.; Lee, Charles
    Copy number variants (CNVs) represent a substantial source of genomic variation in vertebrates and have been associated with numerous human diseases. Despite this, the extent of CNVs in the zebrafish, an important model for human disease, remains unknown. Using 80 zebrafish genomes, representing three commonly used laboratory strains and one native population, we constructed a genome-wide, high-resolution CNV map for the zebrafish comprising 6,080 CNV elements and encompassing 14.6% of the zebrafish reference genome. This amount of copy number variation is four times that previously observed in other vertebrates, including humans. Moreover, 69% of the CNV elements exhibited strain specificity, with the highest number observed for Tubingen. This variation likely arose, in part, from Tubingen's large founding size and composite population origin. Additional population genetic studies also provided important insight into the origins and substructure of these commonly used laboratory strains. This extensive variation among and within zebrafish strains may have functional effects that impact phenotype and, if not properly addressed, such extensive levels of germ-line variation and population substructure in this commonly used model organism can potentially confound studies intended for translation to human diseases.
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    Fine-Mapping the Genetic Association of the Major Histocompatibility Complex in Multiple Sclerosis: HLA and Non-HLA Effects
    (Public Library of Science, 2013) Patsopoulos, Nikolaos; Barcellos, Lisa F.; Hintzen, Rogier Q.; Schaefer, Catherine; van Duijn, Cornelia M.; Noble, Janelle A.; Raj, Towfique; Gourraud, Pierre-Antoine; Stranger, Barbara E.; Oksenberg, Jorge; Olsson, Tomas; Taylor, Bruce V.; Sawcer, Stephen; Hafler, David; Carrington, Mary; De Jager, Philip; de Bakker, Paul I. W.
    The major histocompatibility complex (MHC) region is strongly associated with multiple sclerosis (MS) susceptibility. HLA-DRB1*15:01 has the strongest effect, and several other alleles have been reported at different levels of validation. Using SNP data from genome-wide studies, we imputed and tested classical alleles and amino acid polymorphisms in 8 classical human leukocyte antigen (HLA) genes in 5,091 cases and 9,595 controls. We identified 11 statistically independent effects overall: 6 HLA-DRB1 and one DPB1 alleles in class II, one HLA-A and two B alleles in class I, and one signal in a region spanning from MICB to LST1. This genomic segment does not contain any HLA class I or II genes and provides robust evidence for the involvement of a non-HLA risk allele within the MHC. Interestingly, this region contains the TNF gene, the cognate ligand of the well-validated TNFRSF1A MS susceptibility gene. The classical HLA effects can be explained to some extent by polymorphic amino acid positions in the peptide-binding grooves. This study dissects the independent effects in the MHC, a critical region for MS susceptibility that harbors multiple risk alleles.
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    CD33 Alzheimer’s disease locus: Altered monocyte function and amyloid biology
    (2013) Bradshaw, Elizabeth M.; Chibnik, Lori; Keenan, Brendan T; Ottoboni, Linda; Raj, Towfique; Tang, Anna; Rosenkrantz, Laura L; Imboywa, Selina; Lee, Michelle Ann; Von Korff, Alina; Morris, Martha C; Evans, Denis A; Johnson, Keith; Sperling, Reisa; Schneider, Julie A; Bennett, David A; De Jager, Philip
    In our functional dissection of the CD33 Alzheimer’s disease susceptibility locus, we find that the rs3865444C risk allele is associated with greater cell surface expression of CD33 in monocytes (t50 = 10.06, pjoint=1.3×10–13) of young and older individuals. It is also associated with (1) diminished internalization of Aβ42) (2) accumulation of neuritic amyloid pathology and fibrillar amyloid on in vivo imaging and (3), increased numbers of activated human microglia.
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    Genetics of rheumatoid arthritis contributes to biology and drug discovery
    (2013) Okada, Yukinori; Wu, Di; Trynka, Gosia; Raj, Towfique; Terao, Chikashi; Ikari, Katsunori; Kochi, Yuta; Ohmura, Koichiro; Suzuki, Akari; Yoshida, Shinji; Graham, Robert R.; Manoharan, Arun; Ortmann, Ward; Bhangale, Tushar; Denny, Joshua C.; Carroll, Robert J.; Eyler, Anne E.; Greenberg, Jeffrey D.; Kremer, Joel M.; Pappas, Dimitrios A.; Jiang, Lei; Yin, Jian; Ye, Lingying; Su, Ding-Feng; Yang, Jian; Xie, Gang; Keystone, Ed; Westra, Harm-Jan; Esko, Tõnu; Metspalu, Andres; Zhou, Xuezhong; Gupta, Namrata; Mirel, Daniel; Stahl, Eli A.; Diogo, Dorothée; Cui, Jing; Liao, Katherine; Guo, Michael; Myouzen, Keiko; Kawaguchi, Takahisa; Coenen, Marieke J.H.; van Riel, Piet L.C.M.; van de Laar, Mart A.F.J.; Guchelaar, Henk-Jan; Huizinga, Tom W.J.; Dieudé, Philippe; Mariette, Xavier; Bridges, S. Louis; Zhernakova, Alexandra; Toes, Rene E.M.; Tak, Paul P.; Miceli-Richard, Corinne; Bang, So-Young; Lee, Hye-Soon; Martin, Javier; Gonzalez-Gay, Miguel A.; Rodriguez-Rodriguez, Luis; Rantapää-Dahlqvist, Solbritt; Ärlestig, Lisbeth; Choi, Hyon; Kamatani, Yoichiro; Galan, Pilar; Lathrop, Mark; Eyre, Steve; Bowes, John; Barton, Anne; de Vries, Niek; Moreland, Larry W.; Criswell, Lindsey A.; Karlson, Elizabeth; Taniguchi, Atsuo; Yamada, Ryo; Kubo, Michiaki; Liu, Jun; Bae, Sang-Cheol; Worthington, Jane; Padyukov, Leonid; Klareskog, Lars; Gregersen, Peter K.; Raychaudhuri, Soumya; Stranger, Barbara E.; De Jager, Philip; Franke, Lude; Visscher, Peter M.; Brown, Matthew A.; Yamanaka, Hisashi; Mimori, Tsuneyo; Takahashi, Atsushi; Xu, Huji; Behrens, Timothy W.; Siminovitch, Katherine A.; Momohara, Shigeki; Matsuda, Fumihiko; Yamamoto, Kazuhiko; Plenge, Robert M.
    A major challenge in human genetics is to devise a systematic strategy to integrate disease-associated variants with diverse genomic and biological datasets to provide insight into disease pathogenesis and guide drug discovery for complex traits such as rheumatoid arthritis (RA)1. Here, we performed a genome-wide association study (GWAS) meta-analysis in a total of >100,000 subjects of European and Asian ancestries (29,880 RA cases and 73,758 controls), by evaluating ~10 million single nucleotide polymorphisms (SNPs). We discovered 42 novel RA risk loci at a genome-wide level of significance, bringing the total to 1012–4. We devised an in-silico pipeline using established bioinformatics methods based on functional annotation5, cis-acting expression quantitative trait loci (cis-eQTL)6, and pathway analyses7–9 – as well as novel methods based on genetic overlap with human primary immunodeficiency (PID), hematological cancer somatic mutations and knock-out mouse phenotypes – to identify 98 biological candidate genes at these 101 risk loci. We demonstrate that these genes are the targets of approved therapies for RA, and further suggest that drugs approved for other indications may be repurposed for the treatment of RA. Together, this comprehensive genetic study sheds light on fundamental genes, pathways and cell types that contribute to RA pathogenesis, and provides empirical evidence that the genetics of RA can provide important information for drug discovery.
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    Integration of Sequence Data from a Consanguineous Family with Genetic Data from an Outbred Population Identifies PLB1 as a Candidate Rheumatoid Arthritis Risk Gene
    (Public Library of Science, 2014) Okada, Yukinori; Diogo, Dorothee; Greenberg, Jeffrey D.; Mouassess, Faten; Achkar, Walid A. L.; Fulton, Robert S.; Denny, Joshua C.; Gupta, Namrata; Mirel, Daniel; Gabriel, Stacy; Li, Gang; Kremer, Joel M.; Pappas, Dimitrios A.; Carroll, Robert J.; Eyler, Anne E.; Trynka, Gosia; Stahl, Eli A.; Cui, Jing; Saxena, Richa; Coenen, Marieke J. H.; Guchelaar, Henk-Jan; Huizinga, Tom W. J.; Dieudé, Philippe; Mariette, Xavier; Barton, Anne; Canhão, Helena; Fonseca, João E.; de Vries, Niek; Tak, Paul P.; Moreland, Larry W.; Bridges, S. Louis; Miceli-Richard, Corinne; Choi, Hyon K.; Kamatani, Yoichiro; Galan, Pilar; Lathrop, Mark; Raj, Towfique; De Jager, Philip; Raychaudhuri, Soumya; Worthington, Jane; Padyukov, Leonid; Klareskog, Lars; Siminovitch, Katherine A.; Gregersen, Peter K.; Mardis, Elaine R.; Arayssi, Thurayya; Kazkaz, Layla A.; Plenge, Robert M.
    Integrating genetic data from families with highly penetrant forms of disease together with genetic data from outbred populations represents a promising strategy to uncover the complete frequency spectrum of risk alleles for complex traits such as rheumatoid arthritis (RA). Here, we demonstrate that rare, low-frequency and common alleles at one gene locus, phospholipase B1 (PLB1), might contribute to risk of RA in a 4-generation consanguineous pedigree (Middle Eastern ancestry) and also in unrelated individuals from the general population (European ancestry). Through identity-by-descent (IBD) mapping and whole-exome sequencing, we identified a non-synonymous c.2263G>C (p.G755R) mutation at the PLB1 gene on 2q23, which significantly co-segregated with RA in family members with a dominant mode of inheritance (P = 0.009). We further evaluated PLB1 variants and risk of RA using a GWAS meta-analysis of 8,875 RA cases and 29,367 controls of European ancestry. We identified significant contributions of two independent non-coding variants near PLB1 with risk of RA (rs116018341 [MAF = 0.042] and rs116541814 [MAF = 0.021], combined P = 3.2×10−6). Finally, we performed deep exon sequencing of PLB1 in 1,088 RA cases and 1,088 controls (European ancestry), and identified suggestive dispersion of rare protein-coding variant frequencies between cases and controls (P = 0.049 for C-alpha test and P = 0.055 for SKAT). Together, these data suggest that PLB1 is a candidate risk gene for RA. Future studies to characterize the full spectrum of genetic risk in the PLB1 genetic locus are warranted.
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    Patterns of \(Cis\) Regulatory Variation in Diverse Human Populations
    (Public Library of Science, 2012) Montgomery, Stephen B.; Dimas, Antigone S.; Parts, Leopold; Stegle, Oliver; Ingle, Catherine E.; Sekowska, Magda; Gutierrez-Arcelus, Maria; Nisbett, James; Nica, Alexandra C.; Beazley, Claude; Durbin, Richard; Deloukas, Panos; Dermitzakis, Emmanouil T.; Stranger, Barbara Elaine; Smith, George; Price, Alkes; Raj, Towfique
    The genetic basis of gene expression variation has long been studied with the aim to understand the landscape of regulatory variants, but also more recently to assist in the interpretation and elucidation of disease signals. To date, many studies have looked in specific tissues and population-based samples, but there has been limited assessment of the degree of inter-population variability in regulatory variation. We analyzed genome-wide gene expression in lymphoblastoid cell lines from a total of 726 individuals from 8 global populations from the HapMap3 project and correlated gene expression levels with HapMap3 SNPs located in \(cis\) to the genes. We describe the influence of ancestry on gene expression levels within and between these diverse human populations and uncover a non-negligible impact on global patterns of gene expression. We further dissect the specific functional pathways differentiated between populations. We also identify 5,691 expression quantitative trait loci (eQTLs) after controlling for both non-genetic factors and population admixture and observe that half of the \(cis\)-eQTLs are replicated in one or more of the populations. We highlight patterns of eQTL-sharing between populations, which are partially determined by population genetic relatedness, and discover significant sharing of eQTL effects between Asians, European-admixed, and African subpopulations. Specifically, we observe that both the effect size and the direction of effect for eQTLs are highly conserved across populations. We observe an increasing proximity of eQTLs toward the transcription start site as sharing of eQTLs among populations increases, highlighting that variants close to TSS have stronger effects and therefore are more likely to be detected across a wider panel of populations. Together these results offer a unique picture and resource of the degree of differentiation among human populations in functional regulatory variation and provide an estimate for the transferability of complex trait variants across populations.
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    Genome-Wide Association Study and Gene Expression Analysis Identifies CD84 as a Predictor of Response to Etanercept Therapy in Rheumatoid Arthritis
    (Public Library of Science, 2013) Cui, Jing; Stahl, Eli A.; Saevarsdottir, Saedis; Miceli, Corinne; Diogo, Dorothee; Trynka, Gosia; Raj, Towfique; Mirkov, Maša Umiċeviċ; Canhao, Helena; Ikari, Katsunori; Terao, Chikashi; Okada, Yukinori; Wedrén, Sara; Askling, Johan; Yamanaka, Hisashi; Momohara, Shigeki; Taniguchi, Atsuo; Ohmura, Koichiro; Matsuda, Fumihiko; Mimori, Tsuneyo; Gupta, Namrata; Kuchroo, Manik; Morgan, Ann W.; Isaacs, John D.; Wilson, Anthony G.; Hyrich, Kimme L.; Herenius, Marieke; Doorenspleet, Marieke E.; Tak, Paul-Peter; Crusius, J. Bart A.; van der Horst-Bruinsma, Irene E.; Wolbink, Gert Jan; van Riel, Piet L. C. M.; van de Laar, Mart; Guchelaar, Henk-Jan; Shadick, Nancy; Allaart, Cornelia F.; Huizinga, Tom W. J.; Toes, Rene E. M.; Kimberly, Robert P.; Bridges, S. Louis; Criswell, Lindsey A.; Moreland, Larry W.; Fonseca, João Eurico; de Vries, Niek; Stranger, Barbara E.; De Jager, Philip; Raychaudhuri, Soumya; Weinblatt, Michael; Gregersen, Peter K.; Mariette, Xavier; Barton, Anne; Padyukov, Leonid; Coenen, Marieke J. H.; Karlson, Elizabeth; Plenge, Robert M.
    Anti-tumor necrosis factor alpha (anti-TNF) biologic therapy is a widely used treatment for rheumatoid arthritis (RA). It is unknown why some RA patients fail to respond adequately to anti-TNF therapy, which limits the development of clinical biomarkers to predict response or new drugs to target refractory cases. To understand the biological basis of response to anti-TNF therapy, we conducted a genome-wide association study (GWAS) meta-analysis of more than 2 million common variants in 2,706 RA patients from 13 different collections. Patients were treated with one of three anti-TNF medications: etanercept (n = 733), infliximab (n = 894), or adalimumab (n = 1,071). We identified a SNP (rs6427528) at the 1q23 locus that was associated with change in disease activity score (ΔDAS) in the etanercept subset of patients (P = 8×10−8), but not in the infliximab or adalimumab subsets (P>0.05). The SNP is predicted to disrupt transcription factor binding site motifs in the 3′ UTR of an immune-related gene, CD84, and the allele associated with better response to etanercept was associated with higher CD84 gene expression in peripheral blood mononuclear cells (P = 1×10−11 in 228 non-RA patients and P = 0.004 in 132 RA patients). Consistent with the genetic findings, higher CD84 gene expression correlated with lower cross-sectional DAS (P = 0.02, n = 210) and showed a non-significant trend for better ΔDAS in a subset of RA patients with gene expression data (n = 31, etanercept-treated). A small, multi-ethnic replication showed a non-significant trend towards an association among etanercept-treated RA patients of Portuguese ancestry (n = 139, P = 0.4), but no association among patients of Japanese ancestry (n = 151, P = 0.8). Our study demonstrates that an allele associated with response to etanercept therapy is also associated with CD84 gene expression, and further that CD84 expression correlates with disease activity. These findings support a model in which CD84 genotypes and/or expression may serve as a useful biomarker for response to etanercept treatment in RA patients of European ancestry.
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    Balancing Selection on a Regulatory Region Exhibiting Ancient Variation That Predates Human–Neandertal Divergence
    (Public Library of Science, 2013) Gokcumen, Omer; Zhu, Qihui; Mulder, Lubbertus C. F.; Iskow, Rebecca C.; Austermann, Christian; Scharer, Christopher D.; Raj, Towfique; Boss, Jeremy M.; Sunyaev, Shamil; Price, Alkes; Stranger, Barbara; Simon, Viviana; Lee, Charles
    Ancient population structure shaping contemporary genetic variation has been recently appreciated and has important implications regarding our understanding of the structure of modern human genomes. We identified a ∼36-kb DNA segment in the human genome that displays an ancient substructure. The variation at this locus exists primarily as two highly divergent haplogroups. One of these haplogroups (the NE1 haplogroup) aligns with the Neandertal haplotype and contains a 4.6-kb deletion polymorphism in perfect linkage disequilibrium with 12 single nucleotide polymorphisms (SNPs) across diverse populations. The other haplogroup, which does not contain the 4.6-kb deletion, aligns with the chimpanzee haplotype and is likely ancestral. Africans have higher overall pairwise differences with the Neandertal haplotype than Eurasians do for this NE1 locus (p<10−15). Moreover, the nucleotide diversity at this locus is higher in Eurasians than in Africans. These results mimic signatures of recent Neandertal admixture contributing to this locus. However, an in-depth assessment of the variation in this region across multiple populations reveals that African NE1 haplotypes, albeit rare, harbor more sequence variation than NE1 haplotypes found in Europeans, indicating an ancient African origin of this haplogroup and refuting recent Neandertal admixture. Population genetic analyses of the SNPs within each of these haplogroups, along with genome-wide comparisons revealed significant FST (p = 0.00003) and positive Tajima's D (p = 0.00285) statistics, pointing to non-neutral evolution of this locus. The NE1 locus harbors no protein-coding genes, but contains transcribed sequences as well as sequences with putative regulatory function based on bioinformatic predictions and in vitro experiments. We postulate that the variation observed at this locus predates Human–Neandertal divergence and is evolving under balancing selection, especially among European populations.