Dataset Information

Genes identified in Asian SLE GWASs are also associated with SLE in Caucasian populations.

ABSTRACT: Recent genome-wide association studies (GWASs) conducted in Asian populations have identified novel risk loci for systemic lupus erythematosus (SLE). Here, we genotyped 10 single-nucleotide polymorphisms (SNPs) in eight such loci and investigated their disease associations in three independent Caucasian SLE case-control cohorts recruited from Sweden, Finland and the United States. The disease associations of the SNPs in ETS1, IKZF1, LRRC18-WDFY4, RASGRP3, SLC15A4, TNIP1 and 16p11.2 were replicated, whereas no solid evidence of association was observed for the 7q11.23 locus in the Caucasian cohorts. SLC15A4 was significantly associated with renal involvement in SLE. The association of TNIP1 was more pronounced in SLE patients with renal and immunological disorder, which is corroborated by two previous studies in Asian cohorts. The effects of all the associated SNPs, either conferring risk for or being protective against SLE, were in the same direction in Caucasians and Asians. The magnitudes of the allelic effects for most of the SNPs were also comparable across different ethnic groups. On the contrary, remarkable differences in allele frequencies between Caucasian and Asian populations were observed for all associated SNPs. In conclusion, most of the novel SLE risk loci identified by GWASs in Asian populations were also associated with SLE in Caucasian populations. We observed both similarities and differences with respect to the effect sizes and risk allele frequencies across ethnicities.

SUBMITTER: Wang C

PROVIDER: S-EPMC3746253 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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Genes identified in Asian SLE GWASs are also associated with SLE in Caucasian populations.

Wang Chuan C Ahlford Annika A Järvinen Tiina M TM Nordmark Gunnel G Eloranta Maija-Leena ML Gunnarsson Iva I Svenungsson Elisabet E Padyukov Leonid L Sturfelt Gunnar G Jönsen Andreas A Bengtsson Anders A AA Truedsson Lennart L Eriksson Catharina C Rantapää-Dahlqvist Solbritt S Sjöwall Christopher C Julkunen Heikki H Criswell Lindsey A LA Graham Robert R RR Behrens Timothy W TW Kere Juha J Rönnblom Lars L Syvänen Ann-Christine AC Sandling Johanna K JK

European journal of human genetics : EJHG 20121219 9

Recent genome-wide association studies (GWASs) conducted in Asian populations have identified novel risk loci for systemic lupus erythematosus (SLE). Here, we genotyped 10 single-nucleotide polymorphisms (SNPs) in eight such loci and investigated their disease associations in three independent Caucasian SLE case-control cohorts recruited from Sweden, Finland and the United States. The disease associations of the SNPs in ETS1, IKZF1, LRRC18-WDFY4, RASGRP3, SLC15A4, TNIP1 and 16p11.2 were replicat ...[more]

PMID: 23249952

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Project description:This study constructed a non-gapped bacterial artificial chromosomes (BAC) array containing 3604 BAC clones covering 18 lung cancer-related chromosome imbalance hotspot regions. Using this specialized array, DNA from tumor and normal tissues of 40 Asian and 20 Caucasian non-small cell lung cancer (NSLCL) patients was analyzed by array-comparative genomic hybridization (array-CGH). Block-wise normalization and a Bayes regression approach were used to refine the chromosomal imbalance regions identified by array-CGH. The array-CGH results then analyzed by MetaCore software to identify potential cancer-related genes. Finally, 273 genes showing significantly associated with molecular pathway, cancer biomarker, and gene ontology database, such as ZNF322A on 6p22.1, ARHGAP19 on 10q24.1, FRAT2 on 10q24.1, and PAFAH1B1 on 17p13.3 functioning in MAPK, Rho GTPase, and Wnt, and motility control pathways with frequent copy number gain were selected. This study mapped concisely the novel oncogenes or tumor suppressor genes in lung cancer and revealed insights of difference on chromosomal imbalance between lung cancer from Asian and Caucasian. Clinical samples preparation and DNA extraction: Tissues were collected after obtaining appropriate institutional review board permission and informed consent from the recruited patients. Surgically resected tumor tissue and corresponding normal tissue were collected from 40 patients diagnosed with primary NSCLC admitted to Taipei Veterans General Hospital, Taiwan and 20 Caucasian NSCLC tumor tissues from University of Chicago, USA. Histological classification was determined according to the WHO classification and the tumor-node-metastasis system. Information on the age, sex, tumor type, tumor stage and smoking history of the patients was obtained from hospital records. The genomic DNA was prepared using proteinase K digestion and phenol-chloroform extraction. Array-CGH: The genomic microarray used containing 3604 BAC clones representing the human genome at 18 non-gap chromosome regions. Clone mapping was analyzed using the BAC end pairs database of UCSC Genome Bioinformatics (http://genome.ucsc.edu/). The BAC library used was RP-11, which was provided from Genome Research Center, University of Yang-Ming. The extracted BAC DNA was amplified to 10 μg by Phi29 DNA polymerase reaction (TempliPhi DNA Sequencing Template Amplification Kit, Amersham, Princeton, NJ), and digested by DNaseI (New England Biolabs, Ipswich, MA), and purified by MultiScreen-PCR Plates (Millipore, Danvers, MA). After digestion, the DNA fragments were resolved by gel electrophoresis and the fragment size were optimized to within 0.5–3 kb. Finally, the purified BAC DNA fragments were dotted triplicate in 72 blocks on the glass slides (Corning, NY, USA) with spotting solution (50% DMSO, 50% D2H2O). In brief, approximately 500 ng of tumor genomic DNA and reference DNA (for Asian samples: 28 matched-normal genomic DNA pool; for Caucasian samples: commercial human genomic DNA, Invitrogen) were labeled by random priming using BioPrime DNA Labeling System (Invitrogen) with Cy3-dCTP (tumor) or Cy5-dCTP (reference). Labeled tumor and reference DNA were combined together with 100 μg human Cot-1 DNA (Invitrogen). Hybridization was performed using MAUI hybridization system (BioMcro Systems, Salt Lake City, UT), agitating the hybridization solution for 50 hours at 50℃. The arrays were scanned using scanner GenePix4000B (Axon Instruments, Foster City, CA) and the images were segmented and transformed to Cy3-Cy5 log ratio using GenePix software by Axon Instruments, Inc. (http://www.axon.com). Further data processing, a normalization method called “block-wise normalization”, which normalized the array-CGH data by the log ratio of the self-self hybridization of reference DNA according to the mean and the standard deviations of each array block, was established.

Project description:BackgroundCancer-related genes show racial differences. Therefore, identification and characterization of DNA copy number alteration regions in different racial groups helps to dissect the mechanism of tumorigenesis.MethodsArray-comparative genomic hybridization (array-CGH) was analyzed for DNA copy number profile in 40 Asian and 20 Caucasian lung cancer patients. Three methods including MetaCore analysis for disease and pathway correlations, concordance analysis between array-CGH database and the expression array database, and literature search for copy number variation genes were performed to select novel lung cancer candidate genes. Four candidate oncogenes were validated for DNA copy number and mRNA and protein expression by quantitative polymerase chain reaction (qPCR), chromogenic in situ hybridization (CISH), reverse transcriptase-qPCR (RT-qPCR), and immunohistochemistry (IHC) in more patients.ResultsWe identified 20 chromosomal imbalance regions harboring 459 genes for Caucasian and 17 regions containing 476 genes for Asian lung cancer patients. Seven common chromosomal imbalance regions harboring 117 genes, included gain on 3p13-14, 6p22.1, 9q21.13, 13q14.1, and 17p13.3; and loss on 3p22.2-22.3 and 13q13.3 were found both in Asian and Caucasian patients. Gene validation for four genes including ARHGAP19 (10q24.1) functioning in Rho activity control, FRAT2 (10q24.1) involved in Wnt signaling, PAFAH1B1 (17p13.3) functioning in motility control, and ZNF322A (6p22.1) involved in MAPK signaling was performed using qPCR and RT-qPCR. Mean gene dosage and mRNA expression level of the four candidate genes in tumor tissues were significantly higher than the corresponding normal tissues (P<0.001~P=0.06). In addition, CISH analysis of patients indicated that copy number amplification indeed occurred for ARHGAP19 and ZNF322A genes in lung cancer patients. IHC analysis of paraffin blocks from Asian Caucasian patients demonstrated that the frequency of PAFAH1B1 protein overexpression was 68% in Asian and 70% in Caucasian.ConclusionsOur study provides an invaluable database revealing common and differential imbalance regions at specific chromosomes among Asian and Caucasian lung cancer patients. Four validation methods confirmed our database, which would help in further studies on the mechanism of lung tumorigenesis.

Dataset Information

Genes identified in Asian SLE GWASs are also associated with SLE in Caucasian populations.

Publications

Genes identified in Asian SLE GWASs are also associated with SLE in Caucasian populations.

Similar Datasets

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