Table 3

Overall effect estimation of genotypes resulting from the classification of HLA-DRB1 alleles on rheumatoid arthritis susceptibility

Genotypes

Genotype distribution, n (%)

OR (95% CI)

P values


RA cases, n = 758

Controls, n = 789


S2/S3P

39 (5.1%)

7 (0.9%)

7.25 (3.26–16.14)

<10-5

S3P/S3P

74 (9.8%)

31 (4%)

5.15 (2.91–9.12)

<10-5

S2/S2

24 (3.2%)

8 (1%)

4.95 (2.2–11.18)

<10-4

S2/L

121 (16%)

78 (9.9%)

2.41 (1.60–3.65)

<10-4

S3P/L

179 (23.6%)

136 (17.2%)

2.33 (1.57–3.45)

<10-4

L/L

321 (42.3%)

529 (67%)

1


S1, S2, S3P, S3D, and X allele groups were defined according to the amino acid sequence at positions 70 to 74. According to the approach proposed by Michou and colleagues [9], we pooled the three low-risk allele groups (S1, S3D, and X), so called L alleles. Thus, in subsequent analyses, we considered only three allele groups (S2, S3P, and L alleles), with six corresponding genotypes [12]. The reference genotype is L/L. The combined odds ratios (ORs) and 95% confidence intervals (CIs) evaluate the significance of the global effect of the different HLA-DRB1 genotype groups on rheumatoid arthritis (RA) susceptibility over all population samples. P values were calculated with the Mantel-Haenszel method.

Barnetche et al. Arthritis Research & Therapy 2008 10:R26   doi:10.1186/ar2379

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