The frequency of C4A4 was higher in RA patients compared to controls (RR: 1.86, 95% CI: 1.03-3.35), especially in DR4 positive RA patients compared to DR4 positive controls (RR: 2.58, 95% CI: 1.07-6.25), indicating a positive association of this allotype with RA additional to DR4.
In contrast, in patients with RA abnormal frequencies of the MHC antigens DR4 and DR2 and the extended haplotypes associated with them [B62 BfS C4A3C4B3 DR4 GLO2] and [B7 BfS C4A3C4B1 DR2] confirmed the observations reported on other white populations.
There was no statistically significant differences in C4A or C4B gene frequencies between RA and control groups, although there were trends for C4B*Q0 to be reduced and C4B2 to be increased in DR4 positive RA compared with DR4 positive controls.
These data support the existence of 2 different putative susceptibility haplotypes (HLA-Bw54 or Bw59;C2C; BFS;C4A3;C4B5;DR4.1;DQw4 and C2C;BFS; C4AQ0;C4B1 or C4B2) in Japanese patients with RA.
The metabolism of the C4 allotypes C4A3,B1 and C4A3,BO was studied in five healthy control subjects and six patients with active immunological disease (five with systemic lupus erythematosus and one with rheumatoid arthritis).
We describe here an Nco I restriction fragment length polymorphism of tumor necrosis factor carried by the 8.1 (HLA-A1,B8,BfS,C4AQ0,C4B1,DR3) and the 44.1 (HLA-B44,BfS,C4A3,C4BQ0,DR4) ancestral haplotypes associated with complications of rheumatoid arthritis.