Rapid detection of deletions causing delta beta thalassemia and hereditary persistence of fetal hemoglobin by enzymatic amplification

Abstract

A considerable number of deletions of variable size and position that involve the beta-globin gene complex on chromosome 11 are associated with the clinical entities of hereditary persistence of fetal hemoglobin (HPFH) and delta beta thalassemia. Specific deletions appear to be associated with consistent phenotypes and some are known to be recurrent. To facilitate the molecular diagnosis of uncharacterized patients with HPFH and delta beta thalassemia, oligonucleotide primers have been designed to enzymatically amplify deletion-specific products for nine known deletions, which include those responsible for HPFH-1, HPFH-2, HPFH-3, Spanish (delta beta)zero thalassemia, hemoglobin (Hb) Lepore, Sicilian (delta beta)zero thalassemia, Chinese G gamma(A gamma delta beta)zero thalassemia, Asian-Indian inversion-deletion G gamma(A gamma delta beta)zero thalassemia, and Turkish inversion-deletion (delta beta)zero thalassemia. Using this approach, we have successfully characterized the molecular basis for delta beta thalassemia in 23 individuals from 16 families of diverse ethnic origins. Thirteen individuals from this group were shown to be heterozygous for the 13.4- kb Sicilian deletion, two were heterozygous for the 100-kb Chinese G gamma(A gamma delta beta)zero deletion, four were heterozygous for the Turkish form of inversion-deletion delta beta thalassemia, and three were heterozygous for the Asian-Indian form of inversion-deletion G gamma(A gamma delta beta)zero thalassemia. One Vietnamese subject was heterozygous for a 12.6-kb deletion, which we have fully characterized at the molecular level. Sequence analysis of the breakpoint regions of the Chinese deletion and the Turkish rearrangement indicates that, in each case, the mutation is likely to have arisen from a single origin. This hypothesis is supported by the evident geographical clustering of the various deletions described here.

Next‐generation sequencing as a tool for breakpoint analysis in rearrangements of the globin gene clusters

“…It was able to provide tothe-base resolution of the Asian Indian inversion deletion, the Sicilian deletion, the English IV deletion and the 619 bp beta thalassemia deletion. 7,25 These were all beta globin loci structural variants that had been previously identified within the laboratory.…”

XmnIGγ-polymorphism in six unrelated Pakistani families with Inv/DelGγ(Aγδβ)° δβ-thalassemia

“…The db-thalassemias are mostly caused by gene deletions that can be divided into (db)°and ( A gdb)°, depending on whether the G g gene is preserved or not [1]. In spite of the deletion of the entire dand the b-globin genes, these patients suffer from a very mild disorder, attributed primarily to the production of a relatively large amount of g-chains after the neonatal period.…”

Identification of rare and novel deletions that cause (δβ)0‐thalassaemia and hereditary persistence of foetal haemoglobin in Indian population

“…Two previously reported mutations in the Indian population, G c( A cdb) 0 -deletion/inversion (del-inv) and HPFH-3, were detected by Gap-PCRs using the primers described by Craig et al (7).…”