Table 3. Comparison of HLA-DRB1*04 allele frequencies between Black and White populations.
| HLA DRB1*04 allele | ||||
|---|---|---|---|---|
| n | Frequency* | P-value | OR (95% CI) | |
| Healthy individuals (White, N = 172) | 48 | 0.16 | ||
| Autoimmune TTP (Africans, N = 26) | 1 | 0.019 | 0.006 | 0.10 (0.0025–0.67) |
| Healthy individuals origin | ||||
| Nigeria (N = 258) | 3 | 0.006 | 5.6x10-18 | 32.7 (0.006–0.098) |
| Cameroon (N = 126) | 2 | 0.01 | 8x10-11 | 24 (6.01–206) |
| Burkina-Faso (N = 53) | 0 | 0 | 5.2x10-7 | - |
| Mali (N = 49) | 4 | 0.04 | 0.004 | 4.33 (1.46–17.5) |
| Senegal (N = 112) | 17 | 0.078 | 0.014 | 2.15 (1.13–4.27) |
| Guinea (N = 65) | 10 | 0.077 | 0.06 | 2.12 (0.97–5) |
| Autoimmune TTP (Caribbeans, N = 24) | 2 | 0.042 | 0.04 | 4.23 (0.98–38.5) |
| Healthy individuals origin | ||||
| Martinique (N = 100) | 22 | 0.11 | 0.31 | |
HLA: human leukocyte antigen. OR: Odds ratio. CI: confidence interval. TTP: thrombotic thrombocytopenic purpura. N: total number of patients. n: number of patients bearing the allele.
*Allele frequency was calculated by dividing the number of patients bearing the allele with total number of alleles.
Comparison of phenotypic frequencies between both groups was performed using a 2-tailed Fisher exact test. P<0.05 was considered statistically significant.