pumilio1 (pum1) expression, sickle cell anemia, β-thalassemia intermedia

Conditions: Sickle Cell Disease, Beta Thalassemia Intermedia

Summary: 1. to study the expression pattern of pum1 gene in patients with sickle cell anemia and β-thalassemia intermedia. 2. to detect pum1 protein levels in sickle cell anemia and β-thalassemia intermedia patients. 3. to correlate pum1 gene expression pattern and protein levels with hbf levels in sickle cell anemia and β-thalassemia intermedia patients.

the disorders of β-hemoglobin, sickle cell disease (scd) and β-thalassemia, are major causes of morbidity and mortality worldwide. these diseases are the most common genetic disorders in the world. scd is due to a single base-pair point mutation in the β-globin gene resulting in the substitution of valine for glutamic acid in the β-globin chain. the pathophysiology is directly related to polymerization of deoxygenated hemoglobin, leading to a cascade of pathologic events including erythrocyte sickling, vaso-occlusion, and hemolysis. in β-thalassemia, insufficient production of the β-globin molecule results in an excess of free α-globin chains that can precipitate within erythroid precursors, impairing their maturation and leads to death of these precursors and ineffective production of erythroid cells. as a result, a significant anemia occurs and the consequent expansion of erythroid precursors can lead to secondary problems in bones and other organs. the hemoglobin molecule is a tetramer composed of two subunits of α-like globin peptides and two subunits of the β-like globin peptides, along with heme moieties. β-globin switching from fetal γ-globin (hbg1 and hbg2) to adult β-globin is a developmental process that occurs in erythrocytes at around the time of birth. fetal hemoglobin (hbf) induction in adult erythrocytes is an effective therapeutic strategy for scd and β-thalassemia. pumilio1 (pum1) is a novel target of the erythroid master transcription factor erythroid krüppel-like factor (eklf). pum1 is a member of pumilio-fem3-binding factor (puf) family of sequence specific rna-binding proteins, acts as a posttranscriptional repressor by binding to the 3' untranslated region (3'-utr) of messenger rna (mrna). it peaks during terminal erythroid differentiation and binds to fetal γ-globin (hbg1) mrna and impairs its stability and translation. hbg1 has 2 core pum1 consensus binding sites, but hbg2 and adult globins do not. knockdown of pum1 leads to a robust increase in hbf (∼22%) without affecting β-globin levels in human erythroid cells. moreover, targeting pum1 does not affect erythropoiesis, which provides a potentially safe and effective therapeutic strategy for scd and β-thalassemia. also it was found that elevated hbf levels in the absence of anemia in an individual with a novel heterozygous pum1 mutation in the rna-binding domain, which suggests that pum1 is a critical player during human hemoglobin switching.

Eligibility criteria:
inclusion criteria: * patients with sickle cell anemia and β-thalassemia intermedia. * patients are of both sexes (males and females) at any age. exclusion criteria: * patients with any other type of haemolytic anaemias. * patients on hydroxyurea therapy.