Analysis of Globin Gene Structure in Patients with β Thalassemia by Restriction Endonuclease Mapping

Twenty-six DNA samples from individuals either heterozygous or homozygous for β thalassemia were analyzed by restriction endonu-clease digestion, agarose gel electrophoresis, and Southern blot analysis to define DNA fragments containing portions or all of the β globin gene. A total of twenty-seven genes affected by a β thal-assemia mutation and twenty-two normal β globin genes were examined in Italian, Greek, or Asian individuals. With all four restriction endonucleases used, the fragments generated from DNA of thalassemic individuals were identical to those found in DNA from normal. Thus, gross rearrangement or deletion within the genomic region containing the β globin gene is not characteristic of mutations which cause β thalassemia. A third patient homozygous for pancellular hereditary persistence of fetal hemoglobin was shown to have complete deletion of the δ and β globin genes.