The Sphere of Influence of the Beta-thalassemia Mutation.

The recent article by Conley et al.1 on the lwneditary persistence of fetal hemoglobin presents some interesting data which relate to the etiology of thalassemia. Ingram and Stretton2 postulate that beta-tlmlassemia is due to a mutation within or close to the l)eta gene resulting in decreased beta chain production and a compensatory increase in delta chain ( hemoglobin A., ) and gamma chain (hemoglobin F) production. This assumnes that the beta-thalassemia mutation has an active role in the regulation of i)eta chain production but a passive role in delta chain and hemoglobin A., production. An alternative’ is that the i)eta-thalassemia mutation actively resets 1)0th beta and delta chain production. Conley’s data have some bearing in this regard. Assuming that the hereditary persistence of fetal hemoglobin is due to an inactivation of both the beta and delta genes,3.4 the values for hemoglobin A.) can be rearranged in the following manner: