δbeta;thalassemia in an african-american: Identification of the deletion endpoints and PCR-based diagnosis

We describe an African-American child with βthalassemia 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 βglobin genes. The proband's mother is a simple carrier of the deletion and exhibits the phenotype of δbeta;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 δglobin gene mRNA Cap site and the 3' endpoint located 441 bp downstream of the termination codon of the βglobin gene. Based on this information, we have developed a polymerase chain reaction strategy for the rapid detection of this →beta;thalassemia deletion.