Factor V Leiden G1691A, Prothrombin G20210A, and MTHFR C677T and A1298C Mutations in Patients With Sickle Cell Disease in Tunisia

Sickle cell disease is a genetic disorder characterized by a hypercoagulable state. Several complications in this hemoglobinopathy are increased by thrombosis. Factor V Leiden (FVL), prothrombin (PRT) G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C mutations are major inherited risk factors of thrombotic complications. In this study, our aim was to compare the frequencies of these mutations in sickle cell patients with healthy controls. The study population comprised 35 homozygous Hb S (HBB: c.20A>T) patients, 29 compound heterozygous patients [16 Hb S/β⁰-thalassemia (β⁰-thal), four Hb S/β⁺-thal, seven Hb S/Hb C (HBB: c.19G>A) and two Hb S/Hb O-Arab (HBB: c.364G>A)] and 100 healthy subjects. All patients and controls were subjected to laboratory investigations as well as mutation genotyping. Our findings showed a severe anemia with the lowest values of protein S (PS), protein C (PC) and antithrombin (AT) in the homozygous Hb S group compared to Hb S/Hb C and Hb S/β-thal subjects. No significant difference in FVL genotype between patients and controls was observed, whereas high frequencies of PRT G20210A, MTHFR C677T and MTHFR A1298C mutations in the Hb S patients and a significant association between the MTHFR C677T mutation and Hb S/β⁰-thal were found.

Thrombophilic Mutations Among Patients with Sickle Cell Disease

BACKGROUND

Factor V-Leiden (FVL), Prothrombin (PRT) G20210A, and Methylene Tetrahydro Folate Reductase (MTHFR) C677T and A1298C mutations are major inherited risk factors of thrombotic complications. Our aim in this study was to investigate the prevalence of these mutations among Tunisian sickle cell patients.

METHODS

Study subjects comprised 64 patients and 100 healthy controls. FVL, PRT G20210A, and MTHFR genotypes were determined using a reverse dot blot based method.

RESULTS

In the patient population studied, the prevalence of FV Leiden was not statistically different from controls while a significant prevalence of heterozygous PRT G20210A mutation among patients (10.93%) was found. An increased frequency of the MTHFR 677 C>T genotype was seen among patients as well as controls. The results showed no significant association between the MTHFR A1298C mutation and sickle cell disease (SCD). However, the prevalence of carrier among studied patients was 15.62% compared to 7% among healthy subjects.

CONCLUSIONS

In conclusion, our data suggest a significant association between PRT G20210A and MTHFR C677T and sickle cell disease among Tunisian patients.

Screening for viral hepatitis C in a young Tunisian population (more than 175,000 recruits)

BACKGROUND

In front of the considerable impact of the viral hepatitis C, the prevention is more than ever a priority, based essentially on the screening.

AIM

We realized an epidemiological study in a population of young recruits with the aim of considering prevalence of anti-hepatitis C Virus (anti-HCV) antibodies, describing its epidemiological evolution and establishing a cartography of the viral hepatitis C in Tunisia.

METHODS

Epidemiological retrospective study of prevalence was realized from the data of the screening of anti-HCV antibodies from 2003 till 2012 of all the young recruits suggested to be incorporated for the national service or suggested to be recruited as career soldier. The study was exhaustive concerning 175 322 young and healthy male adults aged between 20 and 30 years old, originating from all parts of Tunisia. The screening was realized by third and fourth generation ELISA tests then validated by Immunoblot.

RESULTS

The prevalence was 0.11% and the confirmed prevalence was 0.07%. The positive subjects were mainly between 20 and 25 years old (82.32%) and 91.05% were detected within the framework of their incorporations to the national service. The lowest prevalence was 0.07% in 2004, and the highest was 0.17% in 2011, without a significant tendency in the increase or in the decrease during the period of study (r = 0.857 ; p = 0.564). The screening of anti-VHC antibodies had an unequal geographical distribution according to a North-South decreasing gradient. The highest proportions were registered in the North-West (23.23%) and the District of Tunis (22.73%), contrary to the South-East which was weakly affected (3.54%). The governorates with the highest proportions were Tunis (19.19%), Bizerte (11.62%) and Jendouba (8.59%), the governorates of Monastir and Tataouine were weakly affected (0.51%).

CONCLUSION

Prevalence of anti-HCV antibodies in the young and male Tunisian population was weak, stable without significant tendency in the increase or in the decrease from 2003 till 2012, characterized by an unequal geographical distribution according to a North-South decreasing gradient.

Association of HLA-DR/DQ polymorphisms with schizophrenia in Tunisian patients

BACKGROUND AND OBJECTIVES

The hypothesis that human leukocyte antigens (HLAs) confer susceptibility to schizophrenic disorders has been tested by studying linkage and association in family samples. Our goal was to evaluate the role of HLA in the risk of developing schizophrenia in a Tunisian population.

DESIGN AND SETTINGS

Blood samples for this case-control study were collected from patients of the Department of Psychiatry at the Military Hospital of Tunisia between July 2012 and May 2013.

METHODS

A total of 140 patients with schizophrenia were recruited for genetic analysis. Controls included 100 persons matched for age, sex, and risk factors. Participants were tested for HLA class II alleles. HLA-DRB1 and HLA-DQB1 alleles were genotyped using polymerase chain reaction sequence-specific primers.

RESULTS

This study indicates that the alleles most responsible for disease susceptibility are DRB1*03 (P < 10-3) and DQB1*02 (P < 10-3) (P denotes probability values). The most protective alleles are DRB1*13 (P=.013) and DQB1*05 (P < 10-3). Further results revealed that DRB1*0301/DQB1*0201(P < 10-3), DRB1*0401/DQB1*0301 (P < 10-3) and DRB1*1101/DQB1*0301 (P < 10-3) are haplotypes most conducive to disease susceptibility.

CONCLUSION

The present findings support an association between schizophrenia and the HLA-DR-DQ locus among a Tunisian population. To our knowledge, this is the first study performed to analyze the association of HLA DRB1/DQB1 alleles on schizophrenia susceptibility in Tunisia.

Thrombophilic risk factors in different types of retinal vein occlusion in Tunisian patients

BACKGROUND

Retinal vein occlusion (RVO) is the second most common cause of vision loss because of retinal vascular disease. There are 2 types of RVO: branch retinal vein occlusion (BRVO) and central retinal vein occlusion (CRVO). The pathogenesis of RVO is multifactorial. The role of factor V Leiden (FVL) and prothrombin mutations was examined in patients with CRVO and BRVO.

METHODS

FVL and prothrombin were investigated by extracting DNA of 88 patients with RVO. Sixteen of the patients were diagnosed with CRVO, 4 with hemispheric retinal vein occlusion, and 68 with BRVO. The genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Significant differences were found in the frequencies of the genotypes for both the FVL (G1691A) (P<10(-3), odds ratio [OR]=17.4, confidence interval [CI]=6.20-59) and prothrombin (G20210A) (P=.007, OR=5.11, CI=1.30-29) polymorphisms between RVO patients and healthy controls. Additionally, the frequency of the GA genotype for the G1691A polymorphism was significantly higher among the patients in a subset of BRVO compared with controls (P<10(-3), OR=21.4, CI=7.34-74.2). However, no statistically significant differences were found in the frequencies of the prothrombin G20210A polymorphism between the BRVO group and healthy controls (P=.09, OR=3.13, CI=64-19.9). The frequency of both G1691A and G20210A genotypes among the patients of a CRVO subgroup was significantly higher compared with controls (P<10(-3), OR=11.4, CI=2.94-44.2; P=.007, OR=10.8, CI=2.15-54.1, respectively), suggesting an association between these polymorphisms and CRVO.

CONCLUSIONS

Large study would be required to understand completely the contribution of these markers in the risk of all types of RVO.

Methylenetetrahydrofolate reductase (C677T and A1298C) polymorphisms, hyperhomocysteinemia, and ischemic stroke in Tunisian patients

OBJECTIVE

The present study evaluated the role of the methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C gene polymorphisms and correlated these results with plasma homocysteine (Hcy) levels in Tunisian ischemic stroke (IS) patients.

METHODS

Overall, 84 patients with IS were included and compared with 100 healthy controls. The most common stroke risk factors were investigated. Fasting plasma Hcy levels were measured. Genotyping of the MTHFR C677T and A1298 polymorphisms was studied by polymerase chain reaction.

RESULTS

Aside from tobacco and alcohol use, the other studied factors were significant risk factors for IS. Mean plasma Hcy levels were significantly higher in IS patients than in controls (16.1 ± 8.28 μmol/L versus 8.76 ± 3.48 μmol/L, P < 10(-3)). Significant associations were found with both the MTHFR 677(CT + TT) and 1298 (AC + CC) genotypes in comparison with controls (P < 10(-3)). A significant synergistic interaction was also found with the double heterozygote MTHFR 677CT/1298AC (P < 10(-3)). Homocysteine levels were significantly higher in IS patients with the MTHFR C677T variant (CT and TT genotypes) (P < 10(-3)); however, the difference was not significant with the MTHFR A1298C variant (AC and CC genotypes) (P = .31).

CONCLUSION

The MTHFR C677T and A1298 polymorphisms (individually or in concert) and hyperhomocysteinemia represent important risk factors for IS. Elevated Hcy levels were found to be associated with the MTHFR C677T variant; however, no significant association was found with the MTHFR A1298C variant.

Apolipoprotein E genotypes associated with Alzheimer disease and concomitant stroke

BACKGROUND

The ɛ4 allele of the apolipoprotein E (APOE) gene is a well-characterized genetic risk factor for Alzheimer disease (AD). The association between stroke and a higher risk for AD has also been reported. Our study sought to determine the relationship between the APOE gene and AD and the comorbid risk of stroke.

METHODS

The subjects of this study consisted of 48 patients with AD and 48 members of a control group. All subjects were genotyped for APOE.

RESULTS

The results clearly show a significant increased risk of AD in carriers of the APOE ε3/ε4 genotype (P = .003, odds ratio [OR] = 4.1) or ε4 allele (P = .001, OR = 4.2). The risk for stroke in AD patients was also increased for carriers of the APOE ε3/ε4 genotype (P = .02, OR = 9.0) and for carriers of the APOE ε4 allele (P = .004, OR = 5.5).

CONCLUSIONS

The present study is the first to establish a relationship between APOE ε4 and concomitant AD and stroke in the Tunisian population.

Association of methylenetetrahydrofolate reductase polymorphisms with susceptibility to Alzheimer's disease

BACKGROUND

Genetic risk factors play an important role in the pathogenesis of Alzheimer's disease (AD). In this case-control study, we examined the C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene and their correlation with this pathology.

OBJECTIVE

To verify the association between MTHFR C677T and A1298C polymorphisms and Alzheimer's disease.

METHOD

This work was conducted as a case-control study. Cases consisted of thirty-eight patients and 100 individuals without dementia constituted the control group. Genotyping of MTHFR polymorphisms was performed on patients and controls.

RESULT

Genetic analyses did not indicate a significant association between the MTHFR C677T mutation and AD (C/T: 63.15% versus 39%, p=0.087). However, the genotype prevalence of the missense variant MTHFR A1298C was significantly different between patients and controls (A/C: 55% versus 7%, p<10(-3)). Our data suggest an association between the MTHFR A1298C mutation and AD; however, the MTHFR C677T mutation did not contribute to susceptibility for AD.

CONCLUSION

The MTHFR A1298C polymorphism is a possible risk factor for Alzheimer's disease.

Association of methylenetetrahydrofolate reductase A1298C polymorphism but not of C677T with multiple sclerosis in Tunisian patients

BACKGROUND AND OBJECTIVE

Multiple sclerosis (MS) is a chronic neurological disease characterized by central nervous system (CNS) inflammation and demyelination of nerve axons. The aim of this study was to investigate a possible association between the methylenetetrahydrofolate reductase (MTHFR) gene and multiple sclerosis in Tunisian patients.

PATIENTS AND METHODS

The genotyping of two missense variants of the methylenetetrahydrofolate reductase (MTHFR) gene, C677T and A1298C was performed in 80 multiple sclerosis patients and 200 healthy controls.

RESULTS

No significant differences were found in the frequency of the MTHFR C677T polymorphism between MS patients and healthy controls. However, the genotype prevalence of the missense variant MTHFR A1298C was significantly different between patients and controls (A/C: 55% versus 7%, p<10(-3); C/C: 13.75% versus 0%, p<10(-3), respectively).

CONCLUSION

Although our preliminary findings suggest no association between the MTHFR C677T variants and MS, there is evidence to suggest a significant association between the MTHFR A1298C polymorphisms and MS.

Combination of factor V Leiden and MTHFR mutations in myocardial infarction

Identifying patients who are at high risk of suffering myocardial infarction can be done by determining risk factors or by the adoption of molecular genetic testing for inherited thrombophilia. We report a case of myocardial infarction at a young age. The patient complained of dyspnea (stage III) and a burning pain of severe intensity that radiated to the left retrosternal side, but was not associated with palpitations or diaphoresis. A number of biochemical parameters were normal except for an elevated creatinine phosphokinase (CPK) level. Genetic testing revealed the subject to be heterozygous for both the factor V leiden and MTHFR C677T polymorphisms. The combination of these two mutations may be a high risk factor for myocardial infarction. Genetic screening for inherited thrombophilia in young patients, especially in the presence of a common risk factor, may be useful for primary thrombopro.phylaxis and in asymptomatic relatives of patients.

Thrombophilic polymorphisms - factor V Leiden G1691A, prothrombin G20210A and MTHFR C677T - in Tunisian patients with cerebral venous thrombosis

Cerebral venous thrombosis (CVT) has been associated with thrombophilic defects. We performed a study to evaluate the role of three single nucleotide polymorphisms (SNP), factor V Leiden G1691A (FVL), prothrombin gene mutation G20210A (FII-G20210A) and methylenotetrahydrofolate reductase variant C677T (MTHFR-C677T), as risk factors for CVT in Tunisian patients. A single center case-control study (26 patients with CVT and 197 controls) was performed. Genomic DNA was tested for the three SNP. The principle finding was the association between FVL and CVT (p<0.001, Odds ratio=6.1, 95% confidence interval=2.3-16.5). However, neither the FII-G20210 (p=0.536) nor the homozygous MTHFR-C677T genotype (p=0.325) variant contributed to the risk of CVT in these Tunisian patients.

Cerebral venous thrombosis associated with homozygous factor V Leiden mutation in a 15-year-old girl of Tunisian origin

Cerebral venous thrombosis (CVT) is a rare disease. It has numerous and complex etiologies. Inherited or acquired prothrombotic states play a key role in the development of this disease, such as factor V G1691A mutation (FV Leiden). A 15-year-old girl presented to the Department of Neurology with a complaint of severe headache with visual blurring. The diagnosis of CVT was not initially suspected because of the patient's condition on presentation. An MRI showed thrombosis in the superior sagittal sinus, confirming venous stroke. Anticardiolipin and antiphospholipid antibodies were assessed. In addition, inherited prothrombotic defects, such as protein C, protein S, and antithrombin deficiencies, and genetic mutations for FV Leiden, prothrombin gene G20210A (FII G20210A), and methyltetrahydrofolate reductase C677T (MTHFR C677T) were studied. All results were unremarkable except for the unique homozygous FV Leiden mutation, which likely contributed to this prothrombotic situation. This study highlights the fact that FV Leiden may play a significant role in the onset of CVT in young patients.

Hyperhomocysteinemia, C677T MTHFR polymorphism and ischemic stroke in Tunisian patients

BACKGROUND

Hyperhomocysteinaemia has been identified as a strong risk factor for ischemic stroke (IS). A point mutation in methylene tetrahydrofolate reductase (MTHFR C677T) has been associated with increased plasma homocysteine (Hcy) levels.

AIM

This preliminary study aimed to investigate whether hyperhomocysteinaemia and/or MTHFR C677T mutation are associated with ischemic stroke.

METHODS

A case-control study including 50 consecutive patients with confirmed IS and 97 controls was performed. Fasting plasma homocysteine levels, MTHFR C677T genotypes were assessed. Other factors such as hypertension, obesity, dyslipidemia, diabetes mellitus, recurrent stroke tobacco and alcohol were investigated.

RESULTS

Mean plasma homocysteine levels were significantly higher in IS patients than in controls (15.83+/-10.60) μmol/L vs 13.78+/-6.29 μmol/L, p=0.04), while no association of MTHFR C677T variant was observed even with homocysteine. The risk to develop ischemic stroke in hyperhomocysteinemic subjects was 2.4 times more than in subjects with normal Hcy levels (OR= 2.4; 95% CI: 1.13-5.06; p<0.05).

CONCLUSION

Our findings suggest that high levels of homocysteine but not MTHFR C677T polymorphism represent risk factors for arterial ischemic stroke in Tunisian subjects.

Polymorphisme ABO dans une population de donneurs de sang tunisiens

The present survey was carried out in the Military Center of Blood Transfusion from January 1998 to December 2001. 63,375 blood donors were concerned coming from different regions of Tunisia. Gene frequencies were found as follows: O = 0.686, A = 0.196 and B = 0.120. Important variations are observed between different regions of the country. The comparison with other countries' results traces the history of the Tunisian population, Tunisia being a strategic point in the Mediterranean region.

Antiphospholipid antibodies: lupus anticoagulants, anticardiolipin and antiphospholipid isotypes in patients with sickle cell disease

Antiphospholipid antibodies were investigated in 37 individuals with sickle cell disease and compared to a control group of 30 healthy subjects. Sickle cell patients included 18 homozygous sickle cell patients, 8 S/beta thalassemic patients and 11 sickle cell trait subjects. In all individuals, antiphospholipid antibodies were explored by lupus anticoagulant (LA) detection and the quantification of IgG and IgM anticardiolipin (aCL) isotypes, total antiphospholipid antibodies (APA) and IgM, IgG and IgA antiphospholipid classes. In homozygous sickle cell patients, mean level of IgG aCL and total APA were significantly increased (17.02 +/- 8.88 GPL/ml, p < 0.05 and 10.64 +/- 10.58 UPL/ml, p < 0.05 respectively). The IgG aCL, total APA and LA frequencies were 22.2%, 44.4% and 62.2%, respectively. APA isotypes were mostly IgG or IgG and IgA. In S/beta thalassemic patients, mean levels of APA were significantly increased (10.81 +/- 7.82 UPL/ml, p< 0.05). Their frequency was 71.4% and they were mostly IgG or IgG and IgA. In patients with sickle cell trait, mean levels of APA were significantly increased (10.84 +/- 5.84 UPL/ml, p < 0.01). Their frequency was 72.7% and mostly of IgG isotype. Our study showed a close association between high APA levels and sickle cell syndrome, however there was no relationship between high levels of antiphospholipid antibodies and the major complications of sickle cell disease.

Anticoagulant profile of iopamidol and meglumine amidotrizoate and their lack of thrombin generation: an in vitro study

The aim of this in vitro study was to sketch the subtle anticoagulant profile of iopamidol 300 mg l/ml (low osmolality non ionic contrast medium) and meglumine amidotrizoate 370 mg l/ml (high osmolality ionic contrast medium) in situations where variable amounts of clotting factors are observed and to check whether thrombin-generation significantly occurred in non anticoagulated blood-contrast materials mixtures. In the first experiment, mixtures of deficient plasmas with a routine plasma pool provided different ranges with variable amounts of clotting factors II, V, VIII, X, XI and XII. For each clotting factor level studied within these ranges, an activated partial thromboplastin time was determined with either contrast material loaded thromboplastin (5% v/v) or glucose loaded thromboplastin (5% v/v) used as a control. In the second experiment fibrino-peptide A (FpA) or modified antithrombin III (ATM) assays were performed in either (9:1) non anti-coagulated blood contrast materials mixtures or blood-glucose mixtures (control). Differing aPTT prolongation profiles were observed when clotting factors V, VIII, XI and XII were lowered in the plasma. However, neither iopamidol nor amidotrizoate induced an aPTT prolongation with decreasing clotting factor II. In the second experiment no significant thrombin generation was observed as both blood-contrast materials mixtures showed significantly lower FpA and ATM levels (p < 0.001) than glucose control after 5 minutes and 10 minutes incubation at room temperature. These findings provide evidence that the use of iopamidol in angiographic procedures does not increase risk of clotting or hemorrhage.

Fibrinolytic response to venous occlusion in patients with homozygous sickle cell disease

The fibrinolytic potential was evaluated in 37 patients with homozygous sickle cell disease and compared to a control group of 30 age- and sex-matched healthy volunteers. In all individuals, the euglobulin clot lysis time and plasma antigen levels of t-Pa and PAI-1 were measured before and after venous occlusion (v.o) for 10 min. The global fibrinolytic activity was normal in 4 patients (good responders to v.o), while it was decreased in 33 patients (poor responders to v.o). Among the latter, 22 patients had significantly increased baseline levels of PAI-1 Ag (82.6 +/- 27.5 ng/ml, p < 0.001) and a normal release of t-Pa Ag after v.o. In contrast, 11 patients had basal values of PAI-1 Ag comparable to those in controls with a defective release of t-Pa Ag after v.o (11.4 +/- 5.2 ng/ml, p < 0.01). These data provide evidence for reduced fibrinolytic capacity resulting from either increased basal levels of PAI-1 or defective release of t-PA.

Abnormalities of coagulation and fibrinolysis in homozygous sickle cell disease

Abnormalities of coagulation and fibrinolysis were studied in a group of 28 children and young adults with homozygous sickle cell disease (SCD), either in the steady state (n = 12) or during painful crisis (n = 16). Coagulation was explored by standard clotting tests and by measurement of prothrombin complex factors, factor VIII (VIII:C) and antithrombin III (ATIII), protein C (PC) and protein S (PS) activities, while fibrinolytic potential was evaluated using D-dimer, tissue plasminogen activator (t-PA) and plasminogen activator inhibitor (PAI-1) assays. In SCD patients, thrombin time (TT) was constantly shortened, both in the steady state (ratio to control 0.83 +/- 0.08, p < 0.0001) and in crisis (0.76 +/- 0.06, p < 0.0001). Mean levels of prothrombin complex were similar in asymptomatic patients to those in controls, but were significantly decreased during sickle cell crisis (p < 0.05 for factor V and p < 0.0001 for factors II, VII and X). Factor VIII:C was significantly increased, both in the steady state (207 +/- 35%, p < 0.0001) and during crisis (208 +/- 34%, p < 0.0001). PS activity was reduced int he steady state (81 +/- 12%, p < 0.01) and further diminished in crisis (68.5 +/- 27.5%, p < 0.001), while D-dimers were significantly elevated during sickle cell crisis (1028 +/- 675 ng/ml, p < 0.001). In all SCD patients, baseline levels of t-PA antigen were comparable to those in controls, whereas concentrations of PAI-1 antigen were significantly increased, either in the steady state (89.7 +/- 26.3 ng/ml, p < 0.0001) or in crisis (75.0 +/- 24.8 ng/ml, p < 0.0001). These results provide evidence for the presence of circulating activated clotting factors in SCD and for an imbalance of the profibrinolytic and antifibrinolytic systems most likely due to increased PAI-1 levels.