Contribution of HLA class I (A, B, C) and HLA class II (DRB1, DQA1, DQB1) alleles and haplotypes in exploring ethnic origin of central Tunisians.

BACKGROUND: Estimation of HLA (Human leukocyte Antigen) alleles' frequencies in populations is essential to explore their ethnic origin. Anthropologic studies of central Tunisian population were rarely reported. Then, in this work, we aimed to explore the origin of central Tunisian population using HLA alleles and haplotypes frequencies. METHODS: HLA class I (A, B, C) and HLA class II (DRB1, DQA1, DQB1) loci genotyping of 272 healthy unrelated organ donors was performed by Polymerase Chain Reaction-Sequence Specific Oligonucleotide (PCR-SSO). We compared central Tunisians with other populations (Arabs, Berbers, Mediterraneans, Europeans, Africans, etc.) using alleles and haplotypes frequencies, genetic distances, Neighbour-Joining dendrogram and correspondence analysis. RESULTS: Among the 19 HLA A alleles, the 26 HLA B alleles, the 13 HLA C alleles, the 15 HLA DRB1 alleles, the 6 HLA DQA1 alleles and the 5 HLA DQB1 alleles identified in the studied population, HLA A*02 (22.8%), HLA B*50 (13.1%), HLA C*06 (21.8%), HLA DRB1*07 (17.8%), HLA DQA1*01 (32.1%) and HLA DQB1*03 (31.6%) were the most frequent alleles. The extended haplotypes HLA A*02-B*50-C*06-DRB1*07-DQA1*02-DQB1*02 (1.97%) was the most frequent HLA six-loci haplotype. CONCLUSION: Central Tunisians were very close to other Tunisian populations, to Iberians and North Africans. They were rather distant from sub-Saharan populations and eastern Mediterraneans especially Arabs although the strong cultural and religious impact of Arabs in this population.

The pharmacogenetics of tacrolimus in renal transplant patients: association with tremors, new-onset diabetes and other clinical events.

Our study is the first study to investigate the effect of SNPs in CYP3A5, CYP3A4, ABCB1 and POR genes on the incidence of tremors, nephrotoxicity, and diabetes mellitus. A total of 223 renal transplant patients receiving tacrolimus and mycophenolate mofetil (MMF) were recruited. Both adults and children patients participated in the study. Genotyping was performed using PROFLEX-PCR followed by RFLP. MPA and tacrolimus plasma concentrations were measured by immunoassay. The AUC0-12h of MMF was estimated by a Bayesian method. We found a statistically significant association between the CYP3A5*3 and CYP3A4*1B genotypes and the tacrolimus exposure. We found a lower occurrence of nephrotoxicity (p = 0.03), tremor (p = 0.01), and new-onset diabetes (p = 0.002) associated with CYP3A5*1 allele. The CYP3A4*1B allele was significantly associated with a lower occurrence of new-onset diabetes (p = 0.026). The CYP3A5*1 allele was significantly associated with an increased risk of acute and chronic rejection (p = 0.03 and p < 0.001, respectively). Our results support the usefulness of tacrolimus pharmacokinetics in pre-kidney transplant assessments.

Single nucleotide polymorphisms of SCN5A and SCN10A genes increase the risk of ventricular arrhythmias during myocardial infarction.

BACKGROUND: Coronary artery disease (CAD) and its ultimate consequence - myocardial infarction (MI) - are major causes of sudden cardiac death (SCD). Previous studies have demonstrated the role of genetic polymorphisms in the risk of SCD and ventricular arrhythmia (VA) during MI. OBJECTIVES: To investigate the association between single nucleotide polymorphisms (SNPs) of genes implicated in congenital cardiac arrhythmias and the risk of developing VA in the context of MI. MATERIAL AND METHODS: We performed a case-control study in which we genotyped 4 SNPs (rs11708996, rs10428132, rs9388451, and rs2200733) in 469 subjects using amplification refractory mutation system (ARMS) and a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). These SNPs are located in the SCN5A, SCN10A, HEY2, and PITX2 genes, respectively. We first compared 70 patients who had developed VA in the context of MI with 141 healthy controls; next, we compared VA patients with 258 MI patients who did not develop VA during a 1-year follow up. The statistical analyses were adjusted for sex and age. RESULTS: Compared to the controls, 2 polymorphisms were significantly associated with the development of VA during MI, located in SCN5A rs11708996 (p = 0.001) and SCN10A rs10428132 (p = 0.001). Similar results were found when comparing VA cases with patients without VA. No associations of HEY2 and PITX2 polymorphisms were observed. CONCLUSIONS: Our results suggest that the rs11708996 and rs10428132 polymorphisms of the SCN5A and SCN10A genes may contribute to an elevated risk of developing VA in the context of MI. The associated alleles or genotypes may be used to predict the risk, and thus prevent eventual SCD.

Distribution of Genetic Polymorphisms of Genes Implicated in Thiopurine Drugs Metabolism.

Thiopurine-S-methyltransferase (TPMT) and inosine triphosphate pyrophosphatase (ITPA) are crucial enzymes involved in the metabolism of thiopurine drugs. Significant interethnic variation in the expression of TPMT and ITPA is caused by single nucleotide polymorphisms of genes encoding these proteins. The aim of this study was to describe the distribution of TPMT and ITPA polymorphisms in healthy Tunisian subjects and to establish the metabolizer status of thiopurine drugs in this population. A total of 309 healthy Tunisian subjects were recruited among blood donors of Fattouma Bourguiba Hospital of Monastir. A written informed consent was obtained from all subjects. Whole blood samples were collected from every subject in ethylenediaminetetraacetic acid tubes. TPMT (c.238 G > C, c.460 G > A and c.719A > G) and ITPA (c.94C > A and IVS2+21A > C) mutations were genotyped using polymerase chain reaction-restriction fragment length polymorphism. The observed frequencies of TPMT*3A and TPMT*3C alleles were both 0.8%. The phenotype distribution of TPMT was bimodal: 96.8% of subjects were extensive metabolizers and 3.2% were intermediate metabolizers. Genotyping of ITPA revealed frequencies of 9% and 3% for IVS2+21A > C and c.94C > A mutations, respectively. Accordingly, a trimodal phenotype distribution was found: 75.4% of the subjects were extensive metabolizers, 23.4% were intermediate metabolizers, and 1.2% wereslow metabolizers. Combination of TPMT and ITPA genotyping has revealed that a quarter of the Tunisian Population carries polymorphisms that reduce the metabolic activities of these enzymes.

Clopidogrel utilization in patients with coronary artery disease and diabetes mellitus: should we determine CYP2C19*2 genotype?

PURPOSE: Clopidogrel non-responsiveness is multifactorial; several genetic and non-genetic factors may contribute to impaired platelet inhibition. The goal of this study is to determine the effect of the cytochrome P450 CYP2C19*2 polymorphism on the platelet response to clopidogrel in patients with and without diabetes mellitus (DM). METHODS: We conducted an observational study in patients with coronary artery disease and consequent exposure to clopidogrel therapy (75 mg/day for at least 7 consecutive days). We have analyzed two groups of patients: group I (DM patients) and group II (non-diabetes mellitus patients). Platelet reactivity was assessed by the VerifyNow P2Y12 assay and high on clopidogrel platelet reactivity (HPR) was defined as P2Y12 reaction units (PRU) ≥ 208. Genotyping for CYP2C19*2 polymorphism was performed by PCR-RFLP. RESULTS: We have included 150 subjects (76 DM and 74 non-diabetes mellitus patients). The carriage of CYP2C19*2 allele, in DM patients, was significantly associated to HPR (odds ratio (OR) 4.437, 95% confidence interval (CI) 1.134 to 17.359; p = 0.032). Furthermore, 8.4% of the variability in percent inhibition by clopidogrel could be attributed to CYP2C19*2 carrier status. However, in non-diabetes mellitus patients, there was no significant difference in platelet response to clopidogrel according to the presence or absence of CYP2C19*2 allele carriage (OR 1.260, 95% CI 0.288 to 5.522; p = 0.759). CONCLUSIONS: Our study suggests that the carriage of CYP2C19*2 polymorphism, in DM patients, might be a potential predictor of persisting HPR in these high-risk individuals. TRIAL REGISTRATION: Clinical Trials.gov NCT03373552 (Registered 13 December 2017).

Does Lipid Profile Affect Thrombin Generation During Ramadan Fasting in Patients With Cardiovascular Risks?

There is evidence that diet and variation in lipid metabolism can influence blood coagulation, but little is known about the effect of Ramadan fasting on plasmatic coagulation pattern. We investigated the effect of Ramadan fasting on thrombin generation (TG) in patients with cardiovascular disease (CVD) risks, and we aimed to assess the effect of lipid profile on TG parameters. The study was conducted in 36 adults having at least 2 CVD risks and in 30 healthy controls. Coagulation pattern was assessed by both classical clotting times and TG test. A complete lipid profile was performed simultaneously. Patients were invited 2 times: 1 week before Ramadan and during the last week of the Ramadan. The TG parameters were not different in patients with CVD risks compared to healthy controls. Fasting had no effect on plasmatic coagulation parameters and on TG profile. Individual analysis of the mean rate index (MRI) of TG revealed 3 groups: group 1 with no modification of MRI, group 2 with a significant increase in MRI (81.64 nM/min vs 136.07 nM/min; P < .001), and group 3 with a significant decrease in MRI (125.27 nM/min vs 73.18 nM/min; P = .001). Only in group 2, a significant increase was observed in total cholesterol and low-density lipoprotein cholesterol. Changes in lipid profile during Ramadan fasting did not influence the global coagulation pattern in patients with CVD risks. Whereas, a significant increase in the propagation phase of TG was associated with a significant increase in cholesterol levels, which was not found with the other TG parameters.

[Platelet satellitism during cutaneous leishmaniasis]. / Satellitisme plaquettaire au cours d'une leishmaniose cutanée.

Platelet satellitism is considered an uncommon phenomenon with an estimated frequency at 0.008%. About 100 cases have been published. If not recognized, this artifact can lead to an erroneous diagnosis of thrombocytopenia. We report the case of a patient, with cutaneous leishmaniasis, who developed an isolated thrombocytopenia. The blood smear prepared from peripheral blood sample collected with ethylenediaminetetraacetic acid showed platelets rosetting around polymorphonuclear. This phenomenon disappeared after treatment with Glucantime® for fifteen days and improvement of the lesions. We discuss also possible mechanisms to better understand this phenomenon.

Antiplatelet effect of once- or twice-daily aspirin dosage in stable coronary artery disease patients with diabetes.

The aim of this pilot study was to compare the effect of two different regimens of aspirin dosage on platelet of coronary artery disease (CAD) diabetic patients. Twenty-five CAD diabetic patients were included. Initially, all patients received aspirin 100 mg/day for 10 days. At day 10, aspirin antiplatelet effect was determined by measuring the collagen/epinephrine closure time (CT) 2 h after the last aspirin dosage and the next morning at 8 a.m.. The aspirin regimen was modified to 100 mg twice daily for patients showing a non-optimal platelet-inhibitory effect (CT < 298 s at 8 a.m.). Persistent high platelet reactivity (HPR) was defined by a CT < 160 s. During the 100 mg/day aspirin regimen, the prevalence of HPR at 8 a.m. was 48%, and only 7 patients (28%) had showed an optimal platelet-inhibitory effect. Bridging to the twice-daily regimen, the HPR was significantly reduced (p=0.025), and the optimal platelet-inhibitory effect was reached for 3 other patients. Our results showed that 100 mg aspirin twice-daily dosing rather than a once-daily dose significantly improves the aspirin effect on platelet of CAD diabetic patients. However, large prospective studies were needed to confirm whether this strategy will be clinically relevant and safe.