Table 3.
FDRs: prevalence of genetic factors, autoantibodies, inflammatory markers, and findings on joint examination, July 2003–September 2008 (N=1058)
| FDR characteristics | N (%) |
|---|---|
| Shared epitope present* (N=982 with testing performed) | |
| ≥1 allele | 538 (55) |
| 1 allele | 451 (46) |
| 2 alleles | 87 (9) |
| PTPN22 polymorphism present (N=980 with testing performed) | |
| ≥1 allele | 196 (20) |
| 1 allele | 183 (19) |
| 2 alleles | 13 (1) |
| Autoantibody positivity | |
| Any autoantibody | 167 (15.9) |
| Anti-CCP and/or ≥2 RF assays | 51 (4.9) |
| Anti-CCP | 18 (1.7) |
| RF-IgM | 50 (4.7) |
| RF-IgG | 65 (6.2) |
| RF-IgA | 40 (3.8) |
| CRP quartiles (reference range 0–3mg/L) | |
| 0–3 mg/L | 753 (71.2) |
| 3–10 mg/L | 250 (23.7) |
| 10–20 mg/L | 36 (3.4) |
| > 20 mg/L | 18 (1.7) |
|
Swollen joint count ≥ 1** Excluding knees |
120 (14.8) 98 (12.1) |
|
Tender joint count ≥ 1** Excluding knees |
203 (24.1) 177 (21.8) |
*
Alleles considered to contain the shared epitope include: DR4: DRB1*0401, 0404, 0405, 0408, 0409, 0410, 0413, 0416, 0419, and 0421; DR1: *0101, 0102, 0104, 0105, 0107, 0108, and 0111.
**
PIPs, MCPs, wrists, elbows, knees, ankles, and MTPs
Abbreviations: FDR=first-degree relative (parent, sibling, offspring) of a proband with rheumatoid arthritis; HLA=human leukocyte antigen; RA=rheumatoid arthritis; anti-CCP=anti-cyclic citrullinated peptide antibodies; RF-IgM, IgG, IgA= rheumatoid factor isotypes; CRP=C-reactive protein