Table 3. C4B Deficiency and Shared Epitope Associated Only in Seropositive RA*.
| Group | SE positivity (%) | p value |
|---|---|---|
| Seropositive RA | 94/113 (83%) | |
| C4B (<2) | 48/50 (96%) | |
| C4B (≥2) | 46/63 (76%) | p<0.0009 |
| Non-Seropositive RA | ||
| C4B (<2) | 24/44 (55%) | p<0.0001 |
| Non-RA/Volunteers | 17/30 (57%) | p<0.0001 |
*
Data shown represents SE frequency in seropositive RA patient population subgrouped on the basis of C4B deficiency p<0.0009. In the non-seropositive RA group, made up of healthy volunteers, non-RA and seronegative RA patients with C4B deficiency (n=44), the frequency of the SE was 55%, similar to that seen in the general population (31,32). Thus, the association of SE with C4B deficiency was significantly greater in the seropositive RA patient population relative to non-seropositive RA controls, 96% vs 55%, p<0.0001 and this was identical to the Non-RA/Volunteer subgroup. In seronegative RA with C4B deficiency, 7/14 contained the SE consistent with the general population (31,32).