Table 1.
Clinical and demographic features of the RA family and case–control data sets
| Study population | N | Female:male ratio | Age of onset (years) | PTPN22 1858T carrier (%)a | Shared epitope carrier (%)b | Anti-CCP status (%) |
|---|---|---|---|---|---|---|
| Stage I | ||||||
| RA cases | 530 | 3.3:1 | 39.2 | 29.1% (n = 154) | 83.8% (n = 444) | 90.8% (n = 481) |
| ASPs | 292 | — | — | 83 | 227 | 259 |
| Stage II (NARAC I) | ||||||
| All RA cases | 908 | 2.8:1 | 45.5 (n = 884) | 27.8% (n = 898) | 97.9% (n = 865) | 100% (n = 907) |
| All controls | 1260 | 2.5:1 | NA | 15.6% (n = 1253) | 44.6% (n = 1159) | NA |
| NEc RA cases | 682 | 2.8:1 | 45.7 (n = 670) | 27.6% (n = 677) | 97.7% (n = 641) | 100% (n = 681) |
| NEc controls | 752 | 2.3:1 | NA | 16.8% (n = 750) | 46.7% (n = 752) | NA |
| Stage III (NARAC II) | ||||||
| All RA cases | 952 | 1.2:1d | 47.2 (n = 917) | 27.4% (n = 947) | NA | 100% (n = 921) |
| All controls | 1760 | NA | NA | 17.2% (n = 1756) | NA | NA |
Abbreviations: ASP, affected sibling pairs; NARAC, North American Rheumatoid Arthritis Consortium; RA, rheumatoid arthritis.
Individuals were PTPN22 1858T carriers if they had one or more 1858T alleles. In Stage II, the PTPN22 1858T allele was associated with RA using all individuals (OR = 2.09, 95% CI: 1.69–2.60) and when restricted by Northern European ancestry (OR = 1.89, 95% CI: 1.45–2.46). In Stage III, the PTPN22 1858T allele was associated with RA (OR = 1.81, 95% CI: 1.49–2.20).
Individuals were shared epitope carriers if they had one or more of the following HLA-DRB1 alleles: 0101, 0102, 0401, 0404, 0405, 0408, 0413, 1001 and 1402. However, four-digit typing was not available for all subjects, thus cases with HLA-DRB1*04/01/10 were assumed to be carriers for shared epitope.
Subjects with at least 90% Northern European ancestry.
Lower female:male ratio reflects overrepresentation of male RA cases from the Veterans Affairs Rheumatoid Arthritis Registry.