anchor.diff:  * If a study does not report a combined p-value, the p-value and effect size from the largest sample size will be reported as long as the initial and replication samples each show an association of p < 1.0 x 10-5.
   * If a study does not include a replication stage, significant SNPs from the discovery stage will be reported.
   * SNP-trait associations that are described as previously known at the time of publication and are statistically significant in the GWAS sample, but are not attempted for replication, are reported.
  -* The most significant SNP from each independent locus is extracted
  +* The most significant SNP from each independent locus is extracted.
   
   === Data extraction
   
   GWAS Catalog data are manually extracted from the literature (either the main text or supporting information) by expert scientists.
  -Following initial extraction all data is double-checked for accuracy and consistency by a second independent curator.
  +Following initial extraction all data is double-checked for accuracy and consistency by an independent curator.
   
   In general the GWAS Catalog contains one entry for each publication.
   However when a publication includes multiple GWAS analyses, for example on different traits or distinct sample cohorts, these may be split into multiple entries.
  -In cases where studies containing multiple GWAS analyses are not split, generally because <5 associations are identified for each analysis, individual SNPs are annotated with the specific trait, sample population or analysis method.
  +In cases where studies containing multiple GWAS analyses are not split, generally because <5 associations are identified for each analysis, individual SNP associations are annotated with the specific trait, sample population or analysis method.
   
   Information on the following study-level fields is extracted. Capitalised titles correspond to column headings in tab delimited file:
   
   * DATE ADDED TO CATALOG: Date added to catalog
   * PUBMEDID: PubMed identification number
   * FIRST AUTHOR: Last name and initials of first author
  -* DATE: Publication date,(online (epub) date if available)
  +* DATE: Publication date, (online (epub) date if available)
   * JOURNAL: Abbreviated journal name
   * LINK: PubMed URL
   * STUDY: Title of paper
   * DISEASE/TRAIT: Description of disease/trait examined in the study
   * INITIAL SAMPLE DESCRIPTION: Sample size and ancestry description for stage 1 of GWAS (summing across multiple Stage 1 populations, if applicable)
   * REPLICATION SAMPLE DESCRIPTION: Sample size and ancestry description for subsequent replication(s) (summing across multiple populations, if applicable)
  -* PLATFORM (SNPS PASSING QC): Manufacturer of genotyping array used in GWAS stage; Number of SNPs passing quality control metrics and included in the GWAS analysis; Also includes notation of “imputed” if imputation is used and "pooled" to denote studies of pooled DNA.
  +* PLATFORM (SNPS PASSING QC): Manufacturer of genotyping array used in GWAS stage; Number of SNPs passing quality control metrics and included in the GWAS analysis; also includes notation of “imputed” if imputation is used and "pooled" to denote studies of pooled DNA.
   * CNV: Study of copy number variation (yes/no).
   
   For each identified SNP, we extract:
  
positive.code: 
  ==== Quality control and SNP mapping
  
  An automated pipeline, run at the NCBI, adds additional SNP specific information associated with the rsID extracted. This information includes the SNP's base pair and cytogenetic location in the current human genome reference assembly, mapped genes and SNP function. This information is then used for queries and in the production of the karyotype diagram. The pipeline also performs checks for missing information, such as SNP identifiers, resolution of the citation in PubMed, existence of SNPs in dbSNP, confirmation of gene names vs. NCBI's Gene database and confirmation that the reported SNP and gene are in the same chromosomal region.
  
  Additional information added by NCBI pipeline. Capitalised titles correspond to column headings in tab delimited file:
  
  * REGION: Cytogenetic region associated with rs number.
  * CHR_ID: Chromosome number associated with rs number.
  * CHR_POS: Chromosomal position, in base pairs, associated with rs number (dbSNP Build 132, NCBI).
  * MAPPED GENE(S): Gene(s) mapped to the strongest SNP. If the SNP is located within a gene, that gene is listed, with multiple overlapping genes separated by “;”. If the SNP is intergenic, the upstream and downstream genes are listed, separated by “-”.
  * UPSTREAM_GENE_ID: Entrez Gene ID for nearest upstream gene to rs number, if not within gene.
  * DOWNSTREAM_GENE_ID: Entrez Gene ID for nearest downstream gene to rs number, if not within gene.
  
negative.code: === Identification of studies
  
  Published GWAS studies are identified through a weekly PubMed search.
  The search terms are "genome-wide" OR "genome AND identification" OR "genome AND association", with limits on the current year and human status.
  
  === Eligibility criteria
  
  