Thalassemia in Japan

Abstract

Thalassemia is caused by a reduced production of one globin chain due to a quantitative imbalance between the α-globin and non-α-globin chains that make up the hemoglobin. It is classified into α- and β-thalassemia and characterized by microcytosis with polycythemia, and a Mentzer index of ≤13 aids in the diagnosis. In the genetic analysis of α-thalassemia, the Southeast Asian type was found to be the most common genetic subtype among Japanese and non-Japanese without a substantial difference. Conversely, the genetic analysis of β-thalassemia revealed differences in the types and frequencies of mutations between Japanese individuals and foreigners living in Japan, with Japanese-specific mutations such as −31 A→G (TATA box). Acquired α-thalassemia exists in exceptional cases, and cases of myelodysplastic syndrome with acquired Hemoglobin H disease have been reported as α-thalassemia myelodysplastic syndrome. Recent trials using a novel therapeutic agent, luspatercept, for transfusion-dependent β-thalassemia revealed that luspatercept safely and significantly reduces the transfusion volume.