Table 1. Main characteristics of the studied population and distribution of the chromosomes used in the analysis.
| Characteristics | Overall | Genotyped at the α-thalassaemia locus | ||
|---|---|---|---|---|
| Homozygous
ancestral (αα/αα) |
Heterozygous
derived (-α/αα) |
Homozygous
derived (-α/-α) |
||
| All subjects, N (%) | 3036 | 1139 (37.5) | 1474 (48.6) | 423 (13.9) |
| Cases | 1432 (47.2) | 588 (19.4) | 673 (22.2) | 171 (5.6) |
| Controls | 1604 (52.8) | 551 (18.1) | 801 (26.4) | 252 (8.3) |
| Gender, N (%) | ||||
| Males | 1543 (50.8) | 579 (19.1) | 750 (24.7) | 214 (7.0) |
| Females | 1493 (49.2) | 560 (18.4) | 724 (23.8) | 209 (6.9) |
| Ethnicity, N (%) | ||||
| Giriama | 1494 (49.2) | 547 (18.0) | 715 (23.6) | 232 (7.7) |
| Chonyi | 946 (31.2) | 342 (11.3) | 482 (15.9) | 122 (4.0) |
| Kauma | 271 (8.9) | 114 (3.8) | 124 (4.1) | 33 (1.1) |
| Others (18) | 325 (10.7) | 136 (4.5) | 153 (5.0) | 36 (1.2) |
|
Thalassaemia
chromosomes, N |
||||
| αα | 3752 | 1139 | 1474 | - |
| -α | 2320 | - | 1474 | 423 |
|
Sickle (rs334)
chromosomes *, N (%) |
||||
| AA | 2730 (89.9) | 1026 (33.8) | 1317 (43.4) | 387 (12.7) |
| AT | 283 (9.3) | 104 (3.4) | 146 (4.8) | 33 (1.1) |
| TT | 23 (0.8) | 9 (0.3) | 11 (0.4) | 3 (0.1) |
Numbers given are for all individuals included in this study, with percentages shown in parentheses by row.
* The A allele encodes for normal β-globin while the T allele encodes for β s-globin such that AT individuals have sickle cell trait and TT individuals have sickle cell disease.