Effects of glutathione S-transferase M1 and T1 deletions on Parkinson's disease risk among a North African population.

PURPOSE: In this study, the effects of glutathione S-transferase polymorphisms Mu1 (GSTM1) and glutathione S-transferase polymorphisms Theta1 (GSTT1) on Parkinson's disease (PD) risk factor were evaluated in a Tunisian population. METHODS: These polymorphisms were analyzed in 229 healthy Tunisian subjects and 64 Tunisian patients with PD, using a polymerase chain reaction (PCR). Statistical analysis was performed using SPSS 18.0. The relative associations between the GST genotypes and PD were assessed by calculating the odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: The study results demonstrated that the individuals with GSTM1 [OR=3.93, 95% CI: 1.98-7.92, P=10-6] and GSTT1 [OR=5.45, 95% CI: 2.90-10.30, p=10-6] were statistically associated with the risk of PD. A significant association was also found between the individuals with both GSTM1/T1 null genotypes and PD risk [OR=22.10, 95% CI: 6.99-73.75, P=10-6]. CONCLUSION: These genotyping findings suggest that the absence of both GSTM1 and GSTT1 activity could be a contributory factor for the development of PD.

Development and validation of the EUROFORGEN NAME (North African and Middle Eastern) ancestry panel.

Inference of biogeographic origin is an important factor in clinical, population and forensic genetics. The information provided by AIMs (Ancestry Informative Markers) can allow the differentiation of major continental population groups, and several AIM panels have been developed for this purpose. However, from these major population groups, Eurasia covers a wide area between two continents that is difficult to differentiate genetically. These populations display a gradual genetic cline from West Europe to South Asia in terms of allele frequency distribution. Although differences have been reported between Europe and South Asia, Middle East populations continue to be a target of further investigations due to the lack of genetic variability, therefore hampering their genetic differentiation from neighboring populations. In the present study, a custom-built ancestry panel was developed to analyze North African and Middle Eastern populations, designated the 'NAME' panel. The NAME panel contains 111 SNPs that have patterns of allele frequency differentiation that can distinguish individuals originating in North Africa and the Middle East when combined with a previous set of 126 Global AIM-SNPs.

Type A competitiveness traits correlate with downregulation of c-Fos expression in patients with type 1 diabetes.

AIM: Type A personality has been associated with increased survival in people with type 1 diabetes (T1D). Systemic low-grade inflammation may play a critical role, as suggested in recent reports, although the links between the inflammatory circulating transcriptome and Type A remain unknown. This prompted our exploration of the potential associations between Type A personality and c-Fos gene expression, a candidate gene closely linked to inflammatory processes, in T1D. METHODS: Type A personality was assessed by Bortner questionnaire in patients with T1D, and two subscales - 'speed' and 'competitiveness' - were used to measure these specific dimensions of Type A. Expression of the c-Fos gene was assessed by a quantitative real-time polymerase chain reaction technique. RESULTS: This pilot study included 20 men with T1D. Multivariable analyses showed an independent inverse association between Type A competitiveness score and c-Fos expression, while a regression model adjusted for age, body mass index and HbA1c levels revealed a significant inverse relationship between c-Fos transcripts and Type A competitiveness (P = 0.003). CONCLUSION: This strong association between Type A competitiveness and reduced c-Fos expression is in line with recent data suggesting a psychobiological influence of the Type A profile in T1D via inflammatory pathways.

Prognostic Value of BCL2 in Women Patients with Invasive Breast Cancer

Background: Breast cancers are heterogeneous, making it essential to recognize several biomarkers for cancer outcome predictions especially in young women where the classical prediction parameters are not suitable. The goal from this study is to evaluate the impact of B cell lymphoma 2 (BCL2), P53 and Ki-67 proteins expression on survival in young women patients with invasive ductal carcinoma. Patients and methods: Samples and clinical data from 238 patients were collected between 2003 and 2017. They were selected according to 2 criteria: age ≤40 years old and most of them are affected by an Invasive Ductal Carcinoma. We evaluated BCL2, P53 and ki-67 expression by immunochemistry test, and then we assessed correlations of these biomarkers expression with patient's clinicopathological characteristics and survival. Results: Triple negative breast cancer group showed a high frequency among our cohort but we emphasize an almost equitable distribution among all molecular groups. Contrary to other studies which reported that luminal A was correlated with better prognosis, our analysis demonstrated that luminal A is correlated with the Scarff, Bloom and Richardson (SBR) grading 2 or SBR grading 3. To better investigate the prognosis, we analyze three biomarkers known by their impact on physiopathology behavior on breast cancer BCL2, ki-67and P53. BCL2 is the more relevant one, it was correlated with molecular subtypes (p=0.0012) and SBR grading (p=0.0016). BCL2 seems to be the good prognostic biomarker related to survival (p=0.004) with a protective role among patients when endocrine therapy is not provided and Lymph Node (LN) involvement is positive (p=0.021, p=0.000 respectively). Conclusions: The classical prognostic parameters based mainly on the molecular classification in breast cancer seem insufficient in the case of young women. BCL2 protein expression analysis provides a better prognostic value. BCL2 should be clinically associated in current practice when young women specimens are diagnosticated.

The WRKY Transcription Factor Family in Citrus: Valuable and Useful Candidate Genes for Citrus Breeding.

WRKY transcription factors belong to a large family of plant transcriptional regulators whose members have been reported to be involved in a wide range of biological roles including plant development, adaptation to environmental constraints and response to several diseases. However, little or poor information is available about WRKY's in Citrus. The recent release of completely assembled genomes sequences of Citrus sinensis and Citrus clementina and the availability of ESTs sequences from other citrus species allowed us to perform a genome survey for Citrus WRKY proteins. In the present study, we identified 100 WRKY members from C. sinensis (51), C. clementina (48) and Citrus unshiu (1), and analyzed their chromosomal distribution, gene structure, gene duplication, syntenic relation and phylogenetic analysis. A phylogenetic tree of 100 Citrus WRKY sequences with their orthologs from Arabidopsis has distinguished seven groups. The CsWRKY genes were distributed across all ten sweet orange chromosomes. A comprehensive approach and an integrative analysis of Citrus WRKY gene expression revealed variable profiles of expression within tissues and stress conditions indicating functional diversification. Thus, candidate Citrus WRKY genes have been proposed as potentially involved in fruit acidification, essential oil biosynthesis and abiotic/biotic stress tolerance. Our results provided essential prerequisites for further WRKY genes cloning and functional analysis with an aim of citrus crop improvement.

Inference of biogeographical ancestry across central regions of Eurasia.

The inference of biogeographical ancestry (BGA) can provide useful information for forensic investigators when there are no suspects to be compared with DNA collected at the crime scene or when no DNA database matches exist. Although public databases are increasing in size and population scope, there is a lack of information regarding genetic variation in Eurasian populations, especially in central regions such as the Middle East. Inhabitants of these regions show a high degree of genetic admixture, characterized by an allele frequency cline running from NW Europe to East Asia. Although a proper differentiation has been established between the cline extremes of western Europe and South Asia, populations geographically located in between, i.e, Middle East and Mediterranean populations, require more detailed study in order to characterize their genetic background as well as to further understand their demographic histories. To initiate these studies, three ancestry informative SNP (AI-SNP) multiplex panels: the SNPforID 34-plex, Eurasiaplex and a novel 33-plex assay were used to describe the ancestry patterns of a total of 24 populations ranging across the longitudinal axis from NW Europe to East Asia. Different ancestry inference approaches, including STRUCTURE, PCA, DAPC and Snipper Bayes analysis, were applied to determine relationships among populations. The structure results show differentiation between continental groups and a NW to SE allele frequency cline running across Eurasian populations. This study adds useful population data that could be used as reference genotypes for future ancestry investigations in forensic cases. The 33-plex assay also includes pigmentation predictive SNPs, but this study primarily focused on Eurasian population differentiation using 33-plex and its combination with the other two AI-SNP sets.

What common biomarkers characterize a triple-negative profile in breast cancer?

Triple-negative breast cancers are not a homogeneous subgroup. There is substantial intra-subgroup diversity in tumor biology, prognosis and treatment sensitivity. Then, these triple-negative phenotype (TNP) groups, having specific features, can be again divided into subclasses based on an added immunohistochemical markers. The challenge in treating TNP breast cancers is that they are not responsive to antiestrogens or trastuzumab secondary to negative receptor status, and as a result have a poor prognosis. Therefore, the presence or absence of supplementary markers could help predict which therapies are best suited for patients based on the pattern that their disease markers show. In this review, we will recapitulate the major supplementary biomarkers related to triple-negative breast cancer, which could give new therapeutic options.

High frequency and founder effect of the CYP3A4*20 loss-of-function allele in the Spanish population classifies CYP3A4 as a polymorphic enzyme.

Cytochrome P450 3A4 (CYP3A4) is a key drug-metabolizing enzyme. Loss-of-function variants have been reported as rare events, and the first demonstration of a CYP3A4 protein lacking functional activity is caused by CYP3A4*20 allele. Here we characterized the world distribution and origin of CYP3A4*20 mutation. CYP3A4*20 was determined in more than 4000 individuals representing different populations, and haplotype analysis was performed using CYP3A polymorphisms and microsatellite markers. CYP3A4*20 allele was present in 1.2% of the Spanish population (up to 3.8% in specific regions), and all CYP3A4*20 carriers had a common haplotype. This is compatible with a Spanish founder effect and classifies CYP3A4 as a polymorphic enzyme. This constitutes the first description of a CYP3A4 loss-of-function variant with high frequency in a population. CYP3A4*20 results together with the key role of CYP3A4 in drug metabolism support screening for rare CYP3A4 functional alleles among subjects with adverse drug events in certain populations.

Association study of CARD8 (p.C10X) and NLRP3 (p.Q705K) variants with rheumatoid arthritis in French and Tunisian populations.

The objective of the study was to investigate the association of caspase activating and recruitment domain 8 (CARD8) and nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain containing 3 (NLRP3) polymorphisms with rheumatoid arthritis (RA) in Tunisian and French populations. CARD8 (c.30T>A, rs2043211) and NLRP3 (c.2113C>A, rs35829419) single nucleotide polymorphisms (SNPs) were genotyped in 100 French RA trio families and 141 Tunisian patients with RA and 191 unrelated healthy controls, using TaqMan(®) allelic discrimination assay. The genetic analyses for the association and linkage in French families were performed using the comparison of allelic frequencies (AFBAC), the genotype relative risk (GRR) and the transmission disequilibrium test (TDT). Data for case and control samples were analysed by chi-square-test, GRR and odds ratio (OR). No significant differences between alleles and genotypes frequencies were detected in French trio and Tunisian patients with RA and controls, either with CARD8 or with NLRP3 SNPs both in French and in Tunisian populations. Moreover, stratifying patients according to the presence of rheumatoid factor (RF), anti-cyclic peptides antibodies (ACPA), erosion, nodules, other autoimmune disease or HLA-DRB1*04-positive subgroups did not show any significant association with CARD8 or NLRP3 (P ≥ 0.05). This study suggests that variations in the innate immunity genes CARD8 (p.C10X) and NLRP3 (p.Q705K) have no effect on RA susceptibility either in the Tunisian or in the French population.

Signal transducer and activator of transcription and the risk of rheumatoid arthritis and thyroid autoimmune disorders.

OBJECTIVES: The signal transducer and activator of transcription 4 (STAT4) gene localised on chromosome 2q32.2-q32.3 is known to be essential for mediating responses to interleukin 12 in lymphocytes and regulating the differentiation of T helper cells. The aim of this study was to investigate the role of the STAT4 gene in susceptibility to rheumatoid arthritis (RA) and autoimmune thyroid diseases (AITDs) in Tunisian case control studies. METHODS: Genotyping of STAT4 rs7574865 single nucleotide polymorphism (SNP) was performed in 140 patients affected with RA, 159 patients affected with AITDs and 200 healthy controls using TaqMan® allelic discrimination assay. Data were analysed by χ2-test, genotype relative risk (GRR) and odds ratio (OR). RESULTS: Our results revealed that frequencies of the T allele and the T/T genotype were significantly higher among RA patients compared to controls (p=0.008; p=0.003, respectively). However, no significant associations with the risk of autoimmune thyroid diseases were detected. Moreover, the stratification of RA patients subgroups revealed a significant association of both T allele and T/T genotype in patients presented erosion (p=0.003; p=0.004, respectively) as well as anti-cyclic peptides-negative RA (ACPA-) (p=0.002; p=0.0003, respectively). Furthermore, genotypic association was found according to the absence of rheumatoid factor antibody (RF) (p=0.0014). But, no significant differences in allele and genotype frequencies of STAT4 rs7574865 polymorphism were detected according to the presence of another autoimmune disease, nodules and in HLA-DRB1*04 and HLA-DRB1*0404 positive subgroups. CONCLUSIONS: Our results support involvement of the STAT4 gene in the genetic susceptibility to RA but not to AITDs in the Tunisian population.

New mutation c.374C>T and a putative disease-associated haplotype within SCN1B gene in Tunisian families with febrile seizures.

BACKGROUND: Febrile seizures (FSs) relatively represent the most common form of childhood seizures. FSs are not thought of as a true epileptic disease but rather as a special syndrome characterized by its provoking factor (fever) and a typical range of 3 months to 5 years. Although specific genes affecting the majority of FS cases have not been identified yet, several genetic loci for FSs have been reported recently. The aim of this report is to search for the gene responsible for FSs in six affected Tunisian families. METHODS: A microsatellite marker analysis was performed on the known FS and generalized epilepsy with febrile seizures plus (GEFS+) loci. According to the results obtained by statistical analyses for the six studied families and in agreement with the involvement of SCN1B gene in the GEFS+ syndrome in previous studies, SCN1B on GEFS+1 locus was considered as one of the potential candidate genes and was tested for mutations by direct sequencing. RESULTS: A sequencing analysis of the SCN1B gene revealed a novel mutation (c.374G>T) that changed an arginine residue with leucine at position 125 of the protein. We consider that the variation R125L may affect the protein structure and stability by the loss of hydrogen bonding. Two identified single nucleotide polymorphisms that are located in a neighboring hypothetical polyadenylation were assumed to compose a putative disease-associated haplotype. CONCLUSION: Our results support that SCN1B is the gene responsible in one amongst the six FS Tunisian families studied and might contribute to the FS susceptibility for the five others.

Diagnostic value of an enzyme-linked immunosorbent assay using the recombinant CT694 species-specific protein of Chlamydia trachomatis.

AIM: To study the performance of the CT694 protein in relation to the microimmunofluorescence (MIF) and the pELISA tests for the serodiagnosis of Chlamydia trachomatis infections. METHODS AND RESULTS: The CT694 protein was produced as recombinant protein and was used as antigen in ELISA test for the detection of C. trachomatis IgG antibodies. The performance of the developed ELISA test was compared to the MIF test at two cut-off values of 16 and 64, and to the specific pELISA test using a panel of 342 sera. These sera were from children MIF C. trachomatis and Chlamydophila pneumoniae negative, patients MIF C. pneumoniae positive, patients MIF C. trachomatis positive, patients suspected to have chlamydial infections diagnosed by the Cobas Amplicor test, healthy blood donors and prostitutes. Our results indicate that the developed ELISA test has performed better compared with the MIF and the pELISA tests. The highest performance was obtained when comparing the developed ELISA test in relation to the pELISA, yielding an overall sensitivity and specificity of 85% and 87% respectively. CONCLUSIONS: The CT694 ELISA showed the best performance when compared to the species-specific pELISA test and may be used for the serodiagnosis of C. trachomatis infections. SIGNIFICANCE AND IMPACT OF THE STUDY: The CT694 ELISA test responds to the criteria of both sensitivity and specificity according to the MIF and pELISA tests and may be used for serodiagnosis of C. trachomatis infections.

[Alexithymia and psoriasis: a case-control study of 53 patients]. / Alexithymie et psoriasis : étude cas-témoin à propos de 53 patients.

INTRODUCTION: Alexithymia was originally defined as the inability to recognize and verbalize emotions. It is characterized by an emptiness of feelings, poverty of imagination or of a life fantasy and difficulties in communicating with other people, as well as lack of positive emotions and a high prevalence of negative emotions. Its presence has been incriminated in the genesis and in the maintenance of various psychosomatic pathologies. Psoriasis, a frequent dermatitis, is classified among psychosomatic pathologies. In fact, the psychological dimension seems important, either in the appearance of the illness, in its evolution or in its prognosis. AIMS OF THE STUDY: Estimate the prevalence of alexithymia among patients with psoriasis. Study the relationship between them. PATIENTS' CHARACTERISTICS: Fifty-three patients with psoriasis consulted the Dermatology Department of the Hedi Chaker University Hospital, in Sfax, Tunisia. Patients' mean age was 42 years (min: 18 years; max: 76 years). The majority was married (58%), coming from middle to low social economic status (86%), and having a primary or secondary school level (84%). Psoriasis was vulgar for 47 patients (89%) and pustular for the others (11%). METHODOLOGY: We built a case-control study of 53 patients with psoriasis. The control group was formed of 53 subjects without psoriasis and paired according sex, age and school level. We evaluated psoriasis severity using the Psoriasis Area and Severity Index (PASI), a standardised instrument permitting assessment of the global severity of psoriasis. A cut off of 12 was used to diagnose severe psoriasis. Alexithymia was assessed with the 20-item version of the Toronto Alexithymia Scale (TAS-20). This instrument has shown to be the best validated instrument for measuring alexithymia. A cut off of 61 was used to diagnose alexithymia. Sociodemographical and clinical data were assessed by a questionnaire that was filled in by the doctor conducting the study. All analyses were performed using the SPSS version 11.0 and with a 95% confidence interval. Differences in groups were tested using student's independent t-test, and Chi-square. RESULTS: The mean score of alexithymia for the patients was 56 (E: 12.1). The mean score of alexithymia for the control group was 45 (E: 9.6). Thirty-nine decimal six percent (n: 21) of patients and 13.2% (n: 7) of controls exhibited alexithymia. Our results confirm the high prevalence of alexithymia among patients with psoriasis (39.6%) compared to controls (13.2%) (p: 0.0002, RR: 3.4). A stress factor was present before the apparition of psoriasis in half of the cases. Psoriasis was severe in 50% of cases. Women with psoriasis (and not men) presented severe psoriasis when they suffered from alexithymia (p: 0.049). The relationship between alexithymia and age was significant from the age of 40 (p: 0.024). The association between psoriasis and another psychosomatic diseases was significantly more important than for the controls (p: 0.03; RR: 4.6). Psoriasis was not correlated to psychoactive substance (tobacco and alcohol, in our study). However, in the group of patients with alexithymia, alcohol consumption was associated with psoriasis severity (p: 0.05). DISCUSSION: In alexithymia, there is a risk that physical and emotional feelings will be used without distinction as signs of psychological distress, which can explain the somatic complaint due to the lack of the expression of psychological suffering. This can lead to the apparition of psoriasis. The relationship between psoriasis and alexithymia is increasingly studied in epidemiological surveys that use different instruments to measure alexithymia. However, the results of these surveys do not concord with ours. Our results demonstrated a close link between the two conditions. Moreover, the risk of further psychosomatic diseases increases in the presence of alexithymia. The consumption of alcohol was also high in cases of severe forms of psoriasis. CONCLUSION: Alexithymia does not appear to be a simple condition, related to psoriasis, but a worsening of the condition, exposing the patient to the association of other psychosomatic diseases and alcoholism, and thus worsening the global prognosis of these patients. The psychological approach, which favours the expression of emotions and permits a symbolic dimension, is as important as the biological approach, and necessary for the improvement of these patients.

Semen quality decline among men in infertile relationships: experience over 12 years in the South of Tunisia.

Concerns about the worldwide decline in semen quality over the past 50 years are increasing. Western countries have shown a decline in semen quality. However, in non-Western countries studies are sparse. We investigated trends in semen parameters between 1996 and 2007 in the Sfax area of southern Tunisia in a sample of 2940 men in infertile relationships. Age at semen collection, duration of sexual abstinence, volume of seminal fluid, the sperm count, percentages of motile and morphologically normal spermatozoa, and semen leukocyte concentration were determined. Linear regression was used to examine trends over time in sperm count, sperm motility, normal morphology, and semen leukocyte concentration. Mean age and semen volume did not change between 1996 and 2007. Data adjusted for age and abstinence showed a decreasing trend in sperm count and percentage of normal morphology over the last 12 years (R(2) = 0.71, P = .0004, and R(2) = 0.87, P < .0001, respectively). There was no significant change in sperm motility. However, semen leukocyte concentration increased significantly over time (R(2) = 0.38, P = .03). These results coincide with the high prevalence of genital infectious diseases in the Sfax area, suggesting that infection may be a potential contributing factor in semen quality decline.

Genetic screening of two Tunisian families with generalized epilepsy with febrile seizures plus.

BACKGROUND AND PURPOSE: Febrile Seizure can be associated with heterogeneous epilepsy phenotypes regrouped in a syndrome called generalized epilepsy with febrile seizures plus (GEFS+). The aim of this report is to search for the gene responsible for GEFS+ in two affected Tunisian families. METHODS: Microsatellite marker analysis was performed on the known FS and GEFS+ loci. According to the results obtained by statistical analyses, GABRG2 on GEFS+3 locus and SCN1A on GEFS+2 locus were considered as two of the potential candidate genes and were tested for mutations by direct sequencing. RESULTS AND CONCLUSIONS: The mutation analysis and statistical test of the GABRG2 gene revealed a disease association with rs211014 in intron 8 (chi(2) = 5.25, P = 0.021). A sequencing analysis of the SCN1A gene was performed for the two tested families and showed a known mutation (c.1811G>A) and a putative disease-associated haplotype in only one family. Our results support that SCN1A is the responsible gene for GEFS+ in one of the two studied Tunisian families and suggest a positive association of an intronic SNP in the GABRG2 gene in both families.

Optimization and biochemical characterization of a bacteriocin from a newly isolated Bacillus subtilis strain 14B for biocontrol of Agrobacterium spp. strains.

AIMS: The identification of a new compound active against Agrobacterium tumefaciens. METHODS AND RESULTS: The culture conditions of a newly isolated Bacillus subtilis strain, designed 14B, were optimized, as a first step, to produce its bacteriocin (termed Bac 14B) for the biocontrol of Agrobacterium spp., the causal agents of the crown gall disease. Bac 14B was then partially purified and biochemically characterized. Bacillus subtilis 14B was observed to produce an antibacterial compound having a protinaceous nature. As estimated by sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE), the semi-purified bacteriocin substance was found to be a monomeric protein with a molecular weight of 21 kDa. While the latter's antimicrobial activity was completely stable during exposure to a temperature range of up to 100 degrees C for 2 h, its initial activity was totally lost at 121 degrees C for 20 min. The maximum bacteriocin production (4096 AU ml(-1)) was recorded after 96 h-incubation in an optimized Luria Bertani medium supplemented with 10 g l(-1) glucose, 15 g l(-1) K(2)HPO(4) and 5 g l(-1) MgSO(4) 7H(2)O at 30 degrees C in a shaking flask culture. Interestingly, the B. subtilis 14B culture supernatant that contained the bacteriocin under study was proved efficient in reducing both the percentage of galled plants and the number of galls in tomato. CONCLUSION: The findings revealed that B. subtilis 14B and its bacteriocin are efficient in reducing the percentage of infections in plants caused by Ag. tumefaciens. SIGNIFICANCE AND IMPACT OF THE STUDY: The results could be useful for the nurserymen who are particularly interested in the biocontrol of the crown gall disease.

Risk genotypes and haplotypes of the GLUT1 gene for type 2 diabetic nephropathy in the Tunisian population.

OBJECTIVE: Diabetic nephropathy (DN) is a long-term complication of both type 1 and type 2 diabetes. Genetic studies on DN have been of little help so far, since several genetic association studies have shown conflicting results. Here we report the findings of a case-control study on five SNPs in the glucose transporter 1 (GLUT1) gene. The study investigated the association of five GLUT1 genotypes and haplotypes with DN. RESEARCH DESIGN AND METHODS: All subjects, 126 DN (cases) and 273 type 2 diabetes (controls), were genotyped using the polymerase chain reaction restriction fragment length polymorphism. RESULTS: The TT and the AA genotypes of the Haell and Enh2 SNP1, increased the risk of DN. The study also identified CGT as the highest risk haplotype (4.4-fold) followed by CAT with an increased risk of DN of 2.6-fold. CONCLUSIONS: The GLUT1 gene confers susceptibility to DN in type 2 diabetes patients in the Tunisian population.

Association of IRF5 gene polymorphisms with rheumatoid arthritis in a Tunisian population.

OBJECTIVE: A strong genetic association of rheumatoid arthritis (RA) with the interferon regulatory factor 5 (IRF5) gene has been described previously in a Swedish population, although this result was not confirmed in a French population. We undertook an association study between IRF5 and the RA phenotype, as well as a study with serological markers of RA, in a Tunisian population. METHODS: A single-nucleotide polymorphism (SNP; rs2004640) was genotyped using a Taqman 5' allelic discrimination assay on an ABI 7500 real-time polymerase chain reaction (PCR) instrument in 140 RA patients and 185 controls. Rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) were determined by enzyme-linked immunosorbent assay (ELISA). Association was assessed based on the chi(2) test and odds ratios (ORs) with 95% confidence intervals (CIs). RESULTS: The frequency of the TT genotype of the IRF5 SNP rs2004640 differed significantly between patients and controls (p = 0.01). This difference was greater when a subgroup of patients with another 'autoimmune' disorder was considered (p = 0.007). A weak but significant association was also found in a subgroup of patients who were positive for ACPA (p = 0.04) or erosion (p = 0.01). CONCLUSIONS: Our results indicate that the TT genotype of the IRF5 (rs2004640) dimorphism is associated with RA in a Tunisian population.