New Born Screening of Hemoglobinopathies in a Center Tunisian Population.

Sickle cell diseases, ß-thalassemia, and other hemoglobinopathies are common in Africa. Their distribution differs from one region to another. There are higher frequencies in Western and Northern Africa. Their clinical complications presented a real public health problem in each country. For this, early treatment can improve the severity of these diseases. Hemoglobinopathies targeted by screening are associated with SCD, ß, and α thalassemia. Our study aim is to report our experience with newborn screening for hemoglobinopathy in Tunis. The 156 newborn's cord blood was collected at the time of childbirth in the center region (Farhat Hached Hôspital). We opted for hemoglobin exploration to achieve maximum efficiency and effectiveness in screening. After that, all patients suspected to have hemoglobinopathies are affected by molecular investigation. Our findings showed the presence of some hemoglobinopathies such as ß-thalassemia and α-thalassemia with the following frequencies: 12% and 0.33%. The molecular results show the presence of HBB: c.93-21G>A, IVS-I-110G>A, HBBc. -106G>A -56G>C, HBBc.404T>C, Hb Yaounde described for the first time in Tunisia and α 3,7 . In conclusion, newborn screening diagnoses neonates with different examples of hemoglobinopathies, which will be beneficial not only for the care of the child but also for genetic counseling of the potential risk's parents.

Novel mutations in Uridyl-diphosphate-glucuronosyl-transferase 1A1 (UGT1A1) gene in Tunisian patients with unconjugated hyperbilirubinemia.

INTRODUCTION: Unconjugated hyperbilirubinemia (UCB) is a feature of Gilbert's syndrome (GS) and Crigler-Najjar's syndrome (CNS), which are two hereditary defects in bilirubin metabolism. Both syndromes are linked to mutations in the UGT1A1 gene, which cause either the decrease or the absence of the UGT1A1 enzymatic activity. Here, we investigated the molecular basis of the UGT1A1 gene in Tunisian patients presenting with unconjugated hyperbilirubinemia. METHODS: Twenty-four patients with UCB were investigated. The screening protocol for hemoglobinopathies, enzymopathies, and membrane defects was executed in all patients. Afterward, the molecular analysis of the entire UGT1A1 gene was performed by DNA Sanger sequencing. Several bioinformatic tools were used to explore the effects of novel mutations. RESULTS: Fifteen different UGT1A1 variations were identified, among which four are described here for the first time. In exon 5, the c.1412C > G; p.(Ala471Gly) and c.1589C > T; p.(Ser530Phe) mutations were detected in patients presenting with CNS type I and GS, respectively. In the 3'UTR region of UGT1A1, the c.*90C > T mutation was detected in 3 patients with CNS type I. In the same region, the c.*388C > T defect was found in a GS patient. A deleterious and damaging effect on the UGT1A1 protein were predicted for both exonic mutations. Furthermore, novel microRNAs were identified as targetting the mutated sequences for the 3'UTR mutations. CONCLUSION: Our study provides novel data on UCB among Tunisians. Furthermore, we report four novel mutations associated with both GS and CNS. The identification of these mutations increases the spectrum of the UGT1A1 mutations and contributes to an understanding of the molecular abnormalities associated with unconjugated hyperbilirubinemia.

New Deletion at Promoter of HBG1 Gene in Sickle Cell Disease Patients With High HbF Level.

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 (α2ßS2), 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.

Homozygous Mutation on the ß-Globin Polyadenylation Signal in a Tunisian Patient with ß-Thalassemia Intermedia and Coinheritance of Gilbert's Syndrome.

We report here the clinical, hematological and molecular data in a 50-year-old patient with ß-thalassemia intermedia (ß-TI) caused by a homozygous ß+ mutation on the ß-globin gene polyadenylation (polyA) signal (AATAAA>AAAAAA). ß Haplotype analysis was accomplished by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Haplotype and framework analysis showed that this mutation is associated with the [- - - - + + +] ß haplotype and framework 1 (CCGCT) (FW1). This mutation was previously reported in the heterozygous state in association with the codon 9 (+TA) mutation in a ß-TI patient originating from Tunisia. To the best of our knowledge, this is the first report describing this mutation in the homozygous state. The case reported here, coinherited Gilbert's syndrome, which is characterized by hyperbilirubinemia. This conclusion was reached by the investigation of the promoter region [A(TA)nTAA] motif of the UGT1A1 gene, showing the (TA)6/(TA)7 genotype.

The role of rs1984112_G at CD36 gene in increasing reticulocyte level among sickle cell disease patients.

AIMS AND BACKGROUND: 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. MATERIAL AND METHODS: This study enrolled 99 unrelated Tunisian subjects (63SS and 36Sß). 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. RESULTS: 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. CONCLUSION: 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.

rs11886868 and rs4671393 of BCL11A associated with HbF level variation and modulate clinical events among sickle cell anemia patients.

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 × 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.

Genetic link with cholelithiasis among pediatric SCA Tunisian patients: Examples of UGT1A1, SLCO1A2 and SLCO1B1.

AIMS AND BACKGROUND: Hyperbilirubinemia is often observed in chronic hemolysis and results in the formation of pigment cholelithiasis that could be increased by the presence of defected enzymes involved in the bilirubin metabolism. Indeed, this is the first report that interested in the study of polymorphisms in genes encoded for enzymes involved in the bilirubin metabolism: rs 4149056 of SLCO1B1 and rs4149000 of SLCO1A2 in combination with rs8175347 and rs887829 of UGT1A1 in order to find a correlation between the polymorphisms studied and the presence of gallstones in a population of sickle cell anemia (SCA) pediatric Tunisians. MATERIAL AND METHODS: Our study involved 102 unrelated Tunisian subjects. All SCA patients are children (less than 16 years old) and were characterized by hyperbilirubinemia and 52 of them have cholelithiasis. The polymorphisms of the candidate genes were analyzed for all subjects by PCR/sequencing. Genotype and allele frequencies between cases and controls were compared using Pearson's chi-square test with a significance threshold of P < 0.05 (compare 2, version 1.02). RESULTS: The novelty of this report is that children carrying the combined genotype of the rs studied: (TA7TA7)/TT/TC/GA have a higher risk to develop gallstones (P = 0.0027, RR = 18.27 (20.0061-915.28)). CONCLUSION: Altogether our data provide the implication of UGT1A1 and SLCO1A2 in sickle cell anemia-related cholelithiasis.

rs11886868 and rs4671393 of BCL11A associated with HbF level variation and modulate clinical events among sickle cell anemia patients.

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 × 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.

[Genetic polymorphism of cytochrome P450 2E1 and the risk of nasopharyngeal carcinoma]. / Polymorphisme génétique du cytochrome P450 2E1 et le risque du cancer du nasopharynx.

Cytochrome P450 2E1 (CYP2E1) is a detoxifying enzyme that belongs to the phase I metabolism of xenobiotics. This enzyme is encoded by a highly polymorphic gene whose common polymorphism corresponds to the substitution of cytosine (C) and thymine (T) at position -1019 (rs2031920). This polymorphism has been identified in several cancers including nasopharyngeal cancer (NPC). The study involved 124 patients with nasopharyngeal carcinoma, compared with 166 healthy controls. The presence or absence of the polymorphism is determined by PCR-RFLP. The frequency comparison between the two groups is determined by the χ(2) test. The analysis of our results showed a significant difference between the two groups regarding the mutant genotype (C2/C2) (5% vs. 0.5%, P=0.04) and has a risk factor for NPC in Tunisia (OR=8.39; CI 95% [0.99-388.1]). Also, the C2 allele was significantly associated with the group of patients than the control group (6% vs. 2%, P=0.016) and increased three times the risk of NPC in Tunisia (OR=2.99, CI 95% [1.12-8.79]). Our results confirm the results reported in other populations and emphasize the importance of the involvement of this gene in the development of detoxification of the NPC, which seems more and more strongly associated with environmental factors.

Gilbert syndrome acts as a risk factor of developing gallstone among ß hemoglobinopathy Tunisian patients.

BACKGROUND: 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. AIM: Herein, we investigated the effect of glibert mutation on the occurrence of pigment cholelithiasis in Tunisian patients with beta (ß) hemoglobinopathy including sickle cell anemia and ß thalassemia (minor). SUBJECTS AND METHODS: Our study included 151 subjects divided in 75 SCA patients and 76 ß 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. RESULTS: Our results show a significant association between genotypes carrying variant (TA)7 and hyperbilirubinemia (p<0.05). 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 (p<0.05). CONCLUSION: 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 ß hemoglobinopathy Tunisian patients.

Association between rs267196 and rs267201 of BMP6 gene and osteonecrosis among sickle cell aneamia patients.

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<0.05 (compare 2, version 1.02). RESULTS: Our findings showed that the patients carried genotype TA of rs 267196 and genotype AG of rs267201 present a high risk factor for developing osteonecrosis RR=1.317 and RR=1.3 respectively. The results showed a significant association between the alleles A of rs 267196 and G of rs267201 and osteonecrosis P=0.0023; RR=2.42 and P=0.041; RR=2.24 respectively. Interestingly, SCA patients with the combined genotype TA/AG were found to be at higher risk of developing osteonecrosis (P=0.009). As for rs408505 and rs449853 of BMP6 gene no significant association was found among SCA patients.

Early complication in sickle cell anemia children due to A(TA)nTAA polymorphism at the promoter of UGT1A1 gene.

AIM: To determine the implication of the polymorphism, namely, A(TA)nTAA of UGT1A1 in 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 polymorphism A(TA)nTAA at the UGT1A1 promoter and the relationships between the various A(TA)nTAA genotypes 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)7 and hyperbilirubinemia (P < 0.05). We demonstrated the association of two genotypes with gallstones formation among SCA children patients: (TA)7/(TA)7 and (TA)7/(TA)8 with P = 8.1 × 10⁻8 and P = 0.01, respectively. (TA)7 and (TA)8 allele variants act as a risk factor for early gallstones formation in SCA patients with P = 5.8 × 10⁻9 and P = 0.01, respectively. As for the control group only the genotype (TA)7/(TA)7 presented 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)7 variant in early gallstones formation in Tunisian SCA children. Interestingly our findings highlighted the association of (TA)8 variant as well, which was not found in previous studies.

Early complication in Sickle Cell Anemia children due to A(TA)_n TAA polymorphism at the promoter of UGT1A1 gene.

AIM: To determine the implication of the polymorphism namely A(TA)nTAA of UGT1A1 in 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 polymorphism A(TA)_{n} TAA at the UGT1A1 promoter and the relationships between the various A(TA)_{n} TAA genotypes 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 carried variant (TA)_{7} and hyperbilirubinemia (p< 0.05). We demonstrated the association of two genotypes with gallstones formation among SCA children patients: (TA)_{7}/(TA)_{7} and (TA)_{7}/(TA)_{8} with p=8.1 × 10^{ - 8} and p=0.01 respectively. (TA)_{7} and (TA)_{8} allele variants act as a risk factor for early gallstones formation in SCA patients with p=5.8 × 10^{ -9} and p=0.01 respectively. As for the control group only the genotype (TA)_{7}/(TA)_{7} presented 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)_{7} variant in early gallstones formation in Tunisian SCA children. Interestingly our findings highlighted the association of (TA)_{8} variant as well, which was not found in previous studies.

Implication of genetic variation at the promoter and exon1 of UGT1A1 in occurrence of cholelithiasis in Tunisia.

Bilirubin is conjugated with glucoronic acid in the liver by UDP-glucuronosyltransferase 1A1 (UGT1A1). Polymorphisms at the promoter region or exon1 of UGT1A1 gene result in unconjugated hyperbilirubinemia and could be at the origin of gallstone formation. The purpose of this study is to determine whether polymorphisms in the promoter area and exon 1 of UGT1A1 can be considered as a risk factor for lithogenesis. Our study involved 76 patients with cholelithiasis as well as 141 unaffected subjects. For each subject an analysis of the bilirubin parameters was performed. We screened genetic variation in the promoter and exon1 UGT1A1 namely the A (TA) nTAA and the six following SNPs: 44T>G, 101C>A, 115C>G, 145C>T, 211G>A and 222 C>A by PCR/sequencing. Our findings show that subjects with (TA)(7) or (TA)(8) variant in their genotypes are associated with high bilirubin level. Furthermore, the comparison between patients and controls according to A(TA)nTAA variation demonstrated that (TA)(6)/(TA)(7) and (TA)(7)/(TA)(7) genotype and (TA)(7) and (TA)(8) alleles were significantly associated with an increased risk of gallstone diseases p=0.0017, p= 6.1 10(-6), p=1.5 10(-6) and p=0.025 respectively. However, polymorphisms in exon1 were normal in all studied subjects except for the 211G>A which appears to be associated with a protective effect p=7.910(-9); OR=0.03, CI95% (0.001-0.158).