β⁰-Thalassemia Trait (IVS-I-1 G→T) in a Japanese Family

Abstract

Three subjects in a family with microcytic and hypochromic anemia were studied; red blood cell morphology indicated aniso-poikilocytosis and hypochromasia. Target and tear-drop cells were also noted. In all three cases evaluated, there was an increase in HbA₂ levels and a decline in the β/α synthesis ratio. Direct cloning and DNA sequencing identified a point mutation (G→T) at position 1 of intervening sequence I. The resulting reduction of β-globin chain synthesis is considered to give rise to β⁰-thalassemia phenotype. This point mutation is to our knowledge, the first case in Japan.
(Internal Medicine 32: 865-868, 1993)