A Large β-Thalassemia Deletion in A Fay of Indonesian-Malay Descent

Abstract

The partial molecular characterization of a large deletion present in two members of an Indonesian-Malay family with β-thalassemia trait is described. Polymerase chain reaction and sequencing analyses of the breakpoint identified a sequence which has previously been described in patients with the 45 kb Filipino β°-thalassemia deletion, i.e. a 5' breakpoint at position -4279 nucleotides 5′ from the Cap site of the β-globin gene. The 3′ breakpoint is located in an L1 family of repetitive sequences at an unknown distance from the β-globin gene. The hematological and hemoglobin data of the patients with this β°-thalassemia deletion further supports the concept that the unusually high Hb A₂ levels are unique to deletions removing the 5′ β-globin gene region, and points to the importance of the 3′ junction sequences for the regulation of Hb F levels in patients with deletional defects of the β-globin gene cluster.