δβ-Thalassemia in an African-American: Identification of the deletion endpoints and PCR-Based diagnosis

Abstract

We describe an African-American child with β-thalassemia intermedia. Molecular studies revealed that the proband is a compound heterozygote for the -29 (A→G) β⁺-thalassemia mutation and an extensive deletion involving the δ- and β-globin genes. The proband's mother is a simple carrier of the deletion and exhibits the phenotype of δβ-thalassemia rather than hereditary persistence of fetal hemoglobin. The deletion spans 11,767 bp, with the 5′ deletion endpoint located 2,455 bp upstream of the δ-globin gene mRNA Cap site and the 3′ endpoint located 441 bp downstream of the termination codon of the β-globin gene. Based on this information, we have developed a polymerase chain reaction strategy for the rapid detection of this →β-thalassemia deletion.