Table 4.
Number of risk alleles and risk allele frequency in Southern Thai blood donors.
| Diagnosis | α-Globin and β-globin genotypes | Number of alleles∗ | Number of risk alleles (risk allele) |
|---|---|---|---|
| Normal, heterozygous α-thalassemia 2, and homozygous α-thalassemia 2 (n = 103) |
αα/αα, −α/αα, −α/−α, and β A/β A | 412 | 0 |
| Heterozygous α-thalassemia 1 (n = 2) | - -SEA/αα, β A/β A | 8 | 2 (- -SEA) |
| Heterozygous β-thalassemia without α- thalassemia (n = 1) |
αα/αα, β 0/+/β A | 4 | 1 (β 0/+) |
| Heterozygous Hb E without α-thalassemia (n = 6) |
αα/αα, β E/β A | 24 | 6 (β E) |
| Double heterozygotes for Hb E/α- thalassemia 1 (n = 2) |
- -SEA/αα, β E/β A | 8 | 4 (2 ∗ β E and 2 ∗ - -SEA) |
| Homozygous Hb E with and without heterozygous α-thalassemia 2 (n = 2) |
−α/αα, αα/αα, and β E/β E | 8 | 4 (β E) |
|
| |||
| Total (n = 116) | 464 | 17 | |
| Risk allele frequency = 17/464 ∗ 100 = 3.7% | |||
- -SEA: α-thalassemia 1 allele with Southeast Asian type deletion; β 0/+: β 0 or β +-thalassemia allele with uncharacterized β-globin gene mutation; β A: normal β-globin gene; β E: Hb E allele.
*The number of alleles was calculated from two alleles of α-globin genotype (αα/αα) and two alleles from β-globin genotype (β/β) [4 alleles were considered per one donor].