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Genotypic heterogeneity and correlation to intergenic haplotype within high HbF β ‐thalassemia intermedia
Author(s) -
Papachatzopoulou Adamantia,
Kourakli Alexandra,
Makropoulou Panagiota,
Kakagianne Theodora,
Sgourou Argyro,
Papadakis Manousos,
Athanassiadou Aglaia
Publication year - 2006
Publication title -
european journal of haematology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 84
eISSN - 1600-0609
pISSN - 0902-4441
DOI - 10.1111/j.1600-0609.2005.00618.x
Subject(s) - intergenic region , biology , haplotype , genetics , fetal hemoglobin , microbiology and biotechnology , genotype , restriction fragment length polymorphism , gene , genome , fetus , pregnancy
Objectives : A molecular study was carried out of β ‐thalassemia intermedia patients, compound heterozygotes for mutations usually found in β ‐thalassemia major, with high levels of HbF in the absence of hereditary persistence of fetal hemoglobin (HPFH) syndrome. Our objective was to locate cis ‐DNA structures, DNA haplotypes, motifs, or polymorphisms that may correlate with the presence of high HbF. Methods : Allele‐specific oligonucleotide (ASO) hybridization was used for the detection of mutations and restriction fragment length polymorphism (RFLP) analysis and automated sequencing for motifs, haplotypes, and polymorphisms. Southern blot was used for investigating α ‐thalassemia and/or α ‐ or γ ‐globin genes triplications. RNA extracted from burst forming unit‐erythroid (BFU‐e) colonies of peripheral blood mononuclear cell cultures was used in reverse transcriptase‐polymerase chain reaction (RT‐PCR) to investigate intergenic transcription. Results : We established that (i) the combination: T haplotype of the A γ ‐ δ ‐globin intergenic region, the motif (TA) 9 N 10 (TA) 10 in the HS2 site of locus control region (LCR), and TAG pre‐G γ haplotype is sufficient but not necessary for high HbF, (ii) the genetic determinant(s) for high HbF involves an element associated with this combination and must be present in the specific R haplotype occurring in β ‐thalassemia intermedia and (iii) the genetic determinant(s) for high HbF does not involve the abolition of intergenic transcription in the A γ ‐ δ ‐globin intergenic region. Conclusions : The genetic determinant(s) of high HbF in the absence of HPFH is linked to intergenic haplotype T and does not disrupt intergenic transcription.