Table 1. Case–control samples for GWAS meta-analysis.

	Case collection	Control collection	Geographical origin	Antibody status	Cases	Controls	Genotyping platform
Meta-analysis	Brigham Rheumatoid Arthritis Sequential Study (BRASS)	Shared controls	Boston, USA	100% CCP+	478	1631	Affymetrix 6.0
	Canada	Canada and shared controls	Toronto, Canada	100% CCP+	589	1554	Illumina 370K
	Epidemiological Investigation of Rheumatoid Arthritis (EIRA)	EIRA	Sweden	100% CCP+	1142	1072	Illumina 317K
5500 cases, 22 621 controls	North American Rheumatoid Arthritis Consortium (NARAC) I	Shared controls	North America	100% CCP+	868	1194	Illumina 550K
	NARAC III	Shared controls	North America	100% CCP+	902	6613	Illumina 317K
	Wellcome Trust Case Control Consortium (WTCCC)	Shared controls from WTCCC	UK	100% RF+ or CCP+	1521	10557	Affymetrix 500K

Abbreviations: CCP, cyclic citrullinated peptide; GWAS, genome-wide association study; RF, rheumatoid factor.

The characteristics of the six case–control collections used in the GWAS meta-analysis are shown.