Beta thalassemia forms are classified using two systems: genotypic and phenotypic. The genotypic system classifies the beta thalassemias based on their zygosity (heterozygous vs. homozygous) as well as degree of the mutation (partial vs. full). In this classification system, there are six forms of beta thalassemia. In the phenotypic system, there are four forms of beta thalassemia that are based upon the degree of clinical symptoms experienced by the patient.
Key: + = partial deletion or inactivation of gene loci, 0 = full deletion or inactivation of gene loci
- Beta thalassemia major
- Beta thalassemia intermedia
- Beta thalassemia minor
- Beta thalassemia minima