The T-->C mutation at position +96 of the untranslated region 3' to the terminating codon of the beta-globin gene is a rare polymorphism that does not cause a beta-thalassemia as previously ascribed.

We have observed a T-->C mutation at position +96 of the untranslated region 3' to the terminating codon of the beta-globin gene in members of two Czech families and one black family. Data from initial studies suggested that this change was the cause of a beta-thalassemia, but continued analyses have provided convincing evidence that this mutation is a simple polymorphism.