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OBJECTIVES The 5' upstream region of the HBG1 gene plays a very important role in the expression of fetal hemoglobin (HbF). In contrast, increased HbF levels can inhibit the deoxygenation-induced polymerization of sickle hemoglobin (α2βS2), which leads to moderation at the clinical level among sickle cell disease (SCD) patients. Thus, we focused on this article on the study of the 5' upstream region of HBG1 among SCD pediatric patients with high levels of HbF. MATERIALS AND METHODS Fifteen SCD pediatric patients were chosen during the first time of diagnosis, and the HbF values were determined before hydoxyurea treatment. The ages at entry ranged from 1 to 8 years. The mutational screening of the 5' upstream region of the HBG1, which extends to -587 bp, was performed by polymerase chain reaction/sequencing. RESULTS HbF values range from 6.9% to 26%. Sequencing results showed the presence of 6 known polymorphisms, which are as follows: RS35993903, RS34844625, RS3020750, RS2860456, RS2860470, and RS12290216. Interestingly, we also found a new deletion of GCAG in the HBG1 promoter at position -273. CONCLUSIONS We described a new mutation, which is a deletion of GCAG in the HBG1 promoter at position -273. This deletion could affect a binding site of a transcription factor unknown so far and thus modulate the expression of the HBG1 gene.

International audience; The pro-inflammatory context of sickle cell disease promotes the liberation of cytokines such as CCL5, encoded by a gene located on chromosome 17. Herein, the occurrence of three variations of CCL5 in sickle cell anemia (SCA) and their relations to two major complications - painful crisis and presence of infections - were investigated. 100 SCA Tunisian patients and 100 healthy subjects were included in the case control study. Then the sample of patients was divided into two groups according to the presence or absence of each complication. The polymorphisms, namely g.-403G>A, g.-28C>G and g.In1.+1T>C, were analyzed by PCR/sequencing. Our findings show the presence of eight genotypes, namely GG, GA and AA of g.-403G>A, CC, CG and GG of g.-28C>G, and TT and TC of g.In1.+1T>C. The frequencies of studied single nucleotide polymorphisms (SNPs) and haplotypes in SCA patients do not differ significantly from healthy control group results. There is also no significant association between the analyzed polymorphisms and complications as for painful crisis and presence of infections (p > 0.05). Altogether, our data support the conclusion that the three polymorphisms of CCL5, namely g.-403G>A, g.-28C>G and g.In1.+1T>C, do not seem to be involved in the clinical variability of SCA in Tunisia.

Mediators of adhesion become a potential new target for pharmacological therapy to struggle the complications of sickle cell disease (SCD). Several mechanisms for increased adherence have been postulated and the well-studied are CD36 and VLA4 which encoded by ITGA4. Herein, we sought to determine whether one polymorphism of CD36 namely: rs1984112 and three exons of ITGA4 (4, 5, and 6) are implicated in hemolytic status and clinical events among SCD Tunisian patients.This study enrolled 99 unrelated Tunisian subjects (63SS and 36Sβ). All SCD patients are children (less than 16 years old). The rs1984112 and the ITGA4's exons 4, 5, and 6 were analyzed for all subjects by PCR/sequencing. The association of each genotype found with both clinical complications and hemolytic status was performed using t-test. Clinical events studied included vaso-occlusive crisis (VOC), osteonecrosis, stroke, frequent infection, priapism, and acute syndrome.The results show that rs1984112_G allele at CD36 gene revealed to be associated with higher levels of reticulocyte count (p 0.01). The statistical result show a near significance of homozygous mutant GG genotype with VOC (p = 0.051). No association between rs1984112_G allele and the clinical severity of SCD were found. Mutational screening of exon 4, 5, and 6 of ITGA4 gene revealed absence of mutated variant.Our results are similar to those found in Portuguese population which reported the role of rs1984112_G in increasing reticulocyte level among SCD patients. Consequently, the rs1984112_G of CD36 could be considered as a reliable biomarker for predicting patients at high risk for vascular occlusions and thus, allows earlier and more effective therapeutic management.

International audience; Aims: Fetal hemoglobin (HbF) modulates the phenotype of sickle cell anemia (SCA) by inhibiting deoxy sickle hemoglobin (HbS) polymerization. HbF genes are genetically regulated, and the level of HbF and its distribution among sickle erythrocytes is highly variable. Herein, we aimed to determine whether two functional polymorphisms of BCL11A are implicated in the variation of HbF and clinical events in SCA Tunisian patients. Material and methods: The studied population consisted of 148 SCA patients with SS phenotype. The group of patients was divided into two subgroups according to the threshold point of %HbF which is 15%. Genotyping of rs11886868 and rs4671393 was performed using PCR/Sequencing. To test for trait association with the candidate SNPs, genotype and allele frequencies between `group who had %HbF < 15' and `group who had %HbF > 15' (controls) were compared using Pearson's chi-square test (compare 2, version 1.02). The association of each genotype and the combined genotype with complications was performed by logistic regression test. Results: Our findings showed that the majority of patients carried genotype CT of rs11886868 and genotypes AG and GG of rs4671393 present HbF level < 15%. RR = 0.08, RR = 0.176, and RR = 0.189, respectively. The results showed a significant association between the alleles T of rs11886868 and G of rs4671393 and %HbF < 15% with P = 0.016; RR = 0.39 and P = 8.9 x 10(-3): RR = 0.567, respectively. Interestingly, the C allele of the rs11886868 and the A allele of the rs46713939 were associated with an ameliorated phenotype in patient's SCA. The combination of the genotypes GG and CT explains more phenotypic variance than the sum of the two BCL11A SNPs taken individually.

As a result of chronic hemolysis, hyperbilirubinemia is often observed, leading to the formation of pigment cholelithiasis which could be busted by the presence of uridine diphosphoglucuronosyltransferase 1A1 defects.Herein, we investigated the effect of glibert mutation on the occurrence of pigment cholelithiasis in Tunisian patients with beta (β) hemoglobinopathy including sickle cell anemia and β thalassemia (minor).Our study included 151 subjects divided in 75 SCA patients and 76 β thalassemia patients. Both groups of patients were divided into two sub-groups according to the presence or absence of cholelithiasis. The relationship between A(TA)nTAA variation of UGT1A1 gene, the serum bilirubin level and the occurrence of cholilithiasis was investigated.Our results show a significant association between genotypes carrying variant (TA)7 and hyperbilirubinemia (p0.05). Furthermore, we demonstrated a significant association between (TA)6/(TA)7 and (TA)7/(TA)7 genotypes with cholelithiasis among sickle cell anemia and thalassemia patients (p0.05).Altogether, our data provide evidence that genotypes (TA)6/(TA)7 and (TA)7/(TA)7 and (TA)7 variant present a risk factor of developing gallstone among β hemoglobinopathy Tunisian patients.

International audience; AIMS: The skeletal manifestations of sickle cell disease are the result of changes in bone and bone marrow caused by chronic tissue hypoxia that is exacerbated by episodic occlusion of the microcirculation by the abnormal sickle cells. Furthermore, the occurrence of osteonecrosis is under the control of some modifier gene. BMP6 (Bone morphogenetic protein) has been reported as associated with osteonecrosis in sickle cell anemia (SCA). Herein, we intend to study the impact of rs267196, rs267201, rs408505 and rs449853 of BMP6 gene in the occurrence of osteonecrosis among sickle cell patients in Tunisia. METHODS: Our study involved 100 SCA patients among whom 19 have osteonecrosis of the head of the femur. The latter polymorphisms of BMP6 gene were analyzed for all subjects by PCR/sequencing. To test for trait association with the candidate SNPs, genotype and allele frequencies between cases (osteonecrosis group) and controls (non-osteonecrosis group) were compared using Pearson's chi_square test with a significance threshold of P

Aim. To determine the implication of the polymorphism, namely,A(TA)nTAAofUGT1A1in lithogenesis for the first time in Tunisia among sickle cell anemia (SCA) children patients.Material and Methods. Our study was performed in 2010 and it involved 76 subjects chosen as control group characterized with normal hemoglobin status and presence of cholelithiasis and 102 SCA pediatric patients among whom 52 have cholelithiasis. We analyzed the polymorphismA(TA)nTAAat theUGT1A1promoter and the relationships between the variousA(TA)nTAAgenotypes and alleles and bilirubin levels and occurrence of cholelithiasis.Results and Discussion. The repartition of genotypes found according to serum bilirubin level shows a significant association between genotypes carrying variant (TA)7and hyperbilirubinemia (). We demonstrated the association of two genotypes with gallstones formation among SCA children patients: (TA)7/(TA)7and (TA)7/(TA)8with and , respectively. (TA)7and (TA)8allele variants act as a risk factor for early gallstones formation in SCA patients with and , respectively. As for the control group only the genotype (TA)7/(TA)7presented a risk factor for gallstones formation.Conclusion. The novelty of this report is that it is the first time that a similar study was made on the Tunisian children sickle cell population and that the results show a clear association of (TA)7variant in early gallstones formation in Tunisian SCA children. Interestingly our findings highlighted the association of (TA)8variant as well, which was not found in previous studies.