Thalassemia Intermedia : Cases in Negro Siblings with Unusual Differences in Minor Hemoglobin Components

Biochemical, genetic, and clinical studies of two adult Negro brothers with clinical thalassemia intermedia are presented. Their hematologic disease appears to have been caused by interactions of thalassemia with another gene which had no phenotypic expression or was non-allelic to the thalassemia locus. These men had striking differences in the proportions of the minor components Hb A₂ and F. It is considered unlikely that these differences were genetically determined. Rather, it is suggested that environmental or individual factors can modify this biochemical expression of thalassemia genes.