The most common forms of hereditary persistence of fetal hemoglobin synthesis (HPFH) and delta beta zero-thalassemia result from simple deletions of the beta-globin gene cluster or from point mutations in the gamma-globin gene promoters.
We suggest that these changes in nuclear protein-binding properties detected in vitro are responsible for the enhanced gamma globin gene expression found in -202 G gamma beta + patients with hereditary persistence of fetal hemoglobin.
Three gamma-globin promoters containing mutations associated with hereditary persistence of fetal hemoglobin (-202 C----G, -196 C----T, and -117 G----A) were not overexpressed in the K562 cell environment, consistent with the hypothesis that these promoters are not overexpressed in fetal erythroblasts, only adult erythroid cells.
Three gamma-globin promoters containing mutations associated with hereditary persistence of fetal hemoglobin (HPFH), -202 C----G, -196 C----T and -117 G----A, were not overexpressed in K562 cells, consistent with the hypothesis that these promoters are not overexpressed in fetal erythroblasts, only in adult red cells.
Some types of nondeletional heterocellular hereditary persistence of fetal hemoglobin (HPFH) appear to be caused by mutations in the beta globin gene cluster near the gamma globin genes, while in other cases the condition is associated with a gene or genes outside the beta globin gene complex.
Genetic evidence indicates that single point mutations in the gamma-globin promoter may be the cause of high expression of the mutated gene in the adult period (Hereditary Persistence of Fetal Hemoglobin, HPFH).
In hereditary persistence of fetal haemoglobin (HPFH), inappropriately high gamma-globin expression in adult life is associated with deletions in the beta-globin cluster or with single-base changes upstream of the gamma-globin genes.
The -175 T greater than C mutation in the promoter of the A gamma- or G gamma-globin gene causes a 50-100 fold increase of the expression of the respective gene in adult erythroid cells (Hereditary Persistence of Fetal Hemoglobin).
The DNA juxtaposed to the gamma-globin genes as a result of a large deletion associated with hereditary persistence of fetal hemoglobin (HPFH) was studied to define the role it may play in maintaining active expression of these genes in adult erythroid cells.
Persistent expression of the gamma-globin gene in adult life has been supposed to be caused by loss of a region located about 3-4 kb 5' to the delta-globin gene from comparison of the extents of deletions in several different forms of delta beta-thalassemia and HPFH (hereditary persistence of fetal hemoglobin).
The region within the hypersensitive site includes all the consensus promoter elements of the gamma-globin genes as well as an octamer sequence located between -182 and -175, and a region associated with a variety of mutations that may cause hereditary persistence of fetal hemoglobin (HPFH).
Recent studies show that the region of DNA brought into close proximity to the fetal gamma-globin genes in deletional forms of hereditary persistence of fetal hemoglobin (HPFH) is selectively hypomethylated (and presumably active) in normal erythroid tissue.
Individuals heterozygous for the Greek (A gamma) variant of hereditary persistence of fetal haemoglobin (HPFH) synthesize Hb F whose gamma-globin chains are predominantly of the A gamma type.
Comparison of these deletions with previously described ones in Negro and in a new Southern Italian case of hereditary persistence of fetal hemoglobin suggests that the deletion of a region centered at a cluster of repetitive sequences approximately 3.5 kilobases 5' to the delta-globin gene may be critical for the persistent expression of high levels of gamma-globin in hereditary persistence of fetal hemoglobin compared to delta beta-thalassemia.
Different 3' end points of deletions causing delta beta-thalassemia and hereditary persistence of fetal hemoglobin: implications for the control of gamma-globin gene expression in man.
An intramolecular triplex in the human gamma-globin 5'-flanking region is altered by point mutations associated with hereditary persistence of fetal hemoglobin.
G gamma A gamma (beta+) hereditary persistence of fetal hemoglobin: the G gamma -158 C-->T mutation in cis to the -175 T-->C mutation of the A gamma-globin gene results in increased G gamma-globin synthesis.
The -198 T-->C and the -175 T-->C transitions involving the proximal gamma-globin gene promoter are associated with the hereditary persistence of fetal hemoglobin (HPFH) phenotype and have been demonstrated to increase promoter activity in erythroid cells using transient and stable transfection systems.
In this system expression of the G gamma-globin gene bearing the point mutation found in a Japanese patient of hereditary persistence of fetal hemoglobin (HPFH) (1) persisted at a equivalent level to beta-globin expression in fetal and adult mice.
In a group of disorders called hereditary persistence of fetal hemoglobin (HPFH), expression of the gamma-globin gene of HbF persists at high levels in adult erythroid cells.
One mutation in a DR1 site causes elevated gamma-globin transcription in human HPFH (hereditary persistence of fetal hemoglobin) syndrome, and we show that this mutation reduces TR2/TR4 binding in vitro.
In order to address these problems, we investigated an enhancer element identified from individuals with deletional hereditary persistence of fetal hemoglobin 2 (HPFH2), a genetic condition characterized by elevated levels of gamma-globin in adults.