Selection for the alpha-thalassemia genes.

Extremely high incidences of single and double deletions of alpha-globin genes are known among Asian populations. To study possible mechanisms for the maintenance of such deletions, mathematical analyses have been conducted. It has been shown that a stable polymorphism can be achieved easily through heterozygote advantage using deterministic models. The results strongly suggest that high incidences of single and double deletion of alpha-globin genes among Asian populations are maintained by some type of heterozygote advantage.