Hereditary Persistence of Fetal Hemoglobin (HPFH) is characterized by
persistent high levels of fetal hemoglobin (HbF) in adults. Several contributory
factors, both genetic and environmental, have been identified 1, but others remain elusive. Ten of twenty-seven
members from a Maltese family presented with HPFH. A genome-wide SNP scan
followed by linkage analysis revealed a candidate region on chromosome
19p13.12–13. Sequencing identified a nonsense mutation in the
KLF1 gene, p.K288X, ablating the DNA binding domain of this
key erythroid transcriptional regulator 2.
Only HPFH family members were heterozygote carriers of this mutation. Expression
profiling on primary erythroid progenitors revealed down-regulation of KLF1
target genes in HPFH samples. Functional assays demonstrated that, in addition
to its established role in adult globin expression, KLF1 is a critical activator
of the BCL11A gene, encoding a suppressor of HbF expression
3. These observations provide a
rationale for the effects of KLF1 haploinsufficiency on HbF
levels.
Inherited haemoglobinopathies are the most common monogenic diseases, with millions of carriers and patients worldwide. At present, we know several hundred disease-causing mutations on the globin gene clusters, in addition to numerous clinically important trans-acting disease modifiers encoded elsewhere and a multitude of polymorphisms with relevance for advanced diagnostic approaches. Moreover, new disease-linked variations are discovered every year that are not included in traditional and often functionally limited locus-specific databases. This paper presents IthaGenes, a new interactive database of haemoglobin variations, which stores information about genes and variations affecting haemoglobin disorders. In addition, IthaGenes organises phenotype, relevant publications and external links, while embedding the NCBI Sequence Viewer for graphical representation of each variation. Finally, IthaGenes is integrated with the companion tool IthaMaps for the display of corresponding epidemiological data on distribution maps. IthaGenes is incorporated in the ITHANET community portal and is free and publicly available at http://www.ithanet.eu/db/ithagenes.
Sickle cell disease and β-thalassaemia are inherited haemoglobinopathies resulting in structural and quantitative changes in the β-globin chain. These changes lead to instability of the generated haemoglobin or to globin chain imbalance, which in turn impact the oxidative environment both intracellularly and extracellularly. The ensuing oxidative stress and the inability of the body to adequately overcome it are, to a large extent, responsible for the pathophysiology of these diseases. This article provides an overview of the main players and control mechanisms involved in the establishment of oxidative stress in these haemoglobinopathies.
We describe the isolation and characterization of Friend of Prmt1 (Fop), a novel chromatin target of protein arginine methyltransferases. Human Fop is encoded by C1orf77, a gene of previously unknown function. We show that Fop is tightly associated with chromatin, and that it is modified by both asymmetric and symmetric arginine methylation in vivo. Furthermore, Fop plays an important role in the ligand-dependent activation of estrogen receptor target genes, including TFF1 (pS2). Fop depletion results in an almost complete block of estradiol-induced promoter occupancy by the estrogen receptor. Our data indicate that Fop recruitment to the promoter is an early critical event in the activation of estradiol-dependent transcription.
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