Table 2 Number and frequency of methylenetetrahydrofolate reductase gene single‐nucleotide polymorphism genotypes in Causasians and African‐Americans with rheumatoid arthritis and controls.
| SNP genotype | African‐Americans with RA (n = 138) | Caucasians with RA (n = 393) | African‐American controls (n = 53) | Caucasian controls (n = 50) |
|---|---|---|---|---|
| 677 CC | 109 (0.79) | 196 (0.50) | 39 (0.75)* | 25 (0.50) |
| CT | 27 (0.20) | 157 (0.40) | 12 (0.23) | 22 (0.44) |
| TT | 2 (0.01) | 40 (0.10) | 1 (0.02) | 3 (0.06) |
| rs2066462 CC | 117 (0.85) | 320 (0.81) | 42 (0.79) | 37 (0.74) |
| CT | 21 (0.15) | 68 (0.18) | 10 (0.19) | 13 (0.26) |
| TT | 0 | 5 (0.01) | 1 (0.02) | 0 |
| 1298 AA | 102 (0.74) | 178 (0.45) | 36 (0.68) | 25 (0.50) |
| AC | 35 (0.25) | 165 (0.42) | 16 (0.30) | 19 (0.38) |
| CC | 1 (0.01) | 50 (0.13) | 1 (0.02) | 6 (0.12) |
| rs4846051 TT | 63 (0.46) | 387 (0.98) | 25 (0.47) | 49 (0.98) |
| TC | 60 (0.43) | 6 (0.02) | 23 (0.43) | 1 (0.02) |
| CC | 15 (0.11) | 0 | 5 (0.09) | 0 |
| rs2274976 GG | 123 (0.93) * | 355 (0.90) | 43 (0.84) * | 46 (0.92) |
| GA | 9 (0.07) | 37 (0.09) | 8 (0.16) | 4 (0.08) |
| AA | 0 | 1 (0.002) | 0 | 0 |
RA, rheumatoid arthritis; SNP, single‐nucleotide polymorphism.
Caucasians with rheumatoid arthritis were from the Iowa rheumatoid arthritis cohort (n = 200),19 the University of Alabama at Birmingham folate trial in rheumatoid arthritis (n = 59)20 and the Immunex rheumatoid arthritis trial (n = 134).21 African‐Americans with rheumatoid arthritis were from the Grady African‐American Rheumatoid Arthritis (GAARA) cohort (n = 108),18 the aforementioned folate trial (n = 18) and Immunex trial (n = 12). *In all, 102 subjects from GAARA were genotyped at the rs2274976 GA SNP; 52 African‐American controls were genotyped at the 677 CT SNP and 51 subjects at the rs2274976 GA SNP.