Table 3 Number and frequency of methylenetetrahydrofolate reductase gene single‐nucleotide polymorphism haplotypes in Causasians and African‐Americans with rheumatoid arthritis and controls.
| SNP haplotype | African‐Americans with RA (n = 138) | Caucasians with RA (n = 393) | African‐American controls (n = 53) | Caucasian controls (n = 50) |
|---|---|---|---|---|
| 1. C/C/A/T/G | 115 (0.417) | 272 (0.346) | 39 (0.368) | 38 (0.380) |
| 2. T/C/A/T/G | 28 (0.102) | 233 (0.296) | 14 (0.132) | 28 (0.280) |
| 3. C/C/C/T/G | 20 (0.073) | 186 (0.237) | 6 (0.057) | 20 (0.200) |
| 4. C/C/A/C/G | 88 (0.321) | 5 (0.010) | 33 (0.311) | 1 (0.010) |
| 5. C/T/C/T/G | 12 (0.044) | 42 (0.053) | 6 (0.057) | 8 (0.080) |
| 6. C/T/C/T/A | 6 (0.024) | 28 (0.036) | 5 (0.047) | 3 (0.030) |
| 7. C/C/C/T/A | 0 | 6 (0.012) | 1 (0.009) | 0 |
| 8. C/T/A/T/A | 2 (0.008) | 2 (0.004) | 1 (0.009) | 1 (0.010) |
| 9. C/T/A/T/G | 2 (0.008) | 4 (0.005) | 0 | 1 (0.010) |
| 10. T/C/C/T/G | 0 | 4 (0.008) | 0 | 0 |
| 11. C/C/A/T/A | 1(0.004) | 2 (0.004) | 1 (0.009) | 0 |
| 12. C/T/A/C/G | 0 | 1 (0.002) | 0 | 0 |
| 13. T/T/A/T/G | 1 (0.004) | 0 | 0 | 0 |
| 14. T/C/A/T/A | 0 | 1 (0.002) | 0 | 0 |
| 15. T/C/A/C/G | 2 (0.007) | 0 | 0 | 0 |
RA, rheumatoid arthritis; SNP, single‐nucleotide polymorphism.
Haplotypes were defined by the five SNPs shown in table 1: 677 (rs1801133), rs2066462, 1298 (rs1801131), rs4846051 and rs2274976. The difference in haplotype distribution between Caucasians and African‐Americans with rheumatoid arthritis was significant (p = 0.001).