HLA-A*26-A*30 and HLA-DRB1*10 could be predictors of nasopharyngeal carcinoma risk in high-risk Tunisian families.

We investigated human leukocyte antigen (HLA) profiles for Tunisians with nasopharyngeal carcinoma (NPC), their families, and a sample of unrelated healthy Tunisians in order to identify HLA specificities associated with familial NPC. HLA-A, -B, and -DRB1 typing was successful for 36 NPC patients, 72 unaffected family members, and 130 community controls, and the chi square or Fisher exact test was used to compare allele frequencies between cases and controls. We observed a consistent protective effect of HLA-DRB1*10 on NPC development. However, none of the NPC patients or their family members had a positive result for this HLA marker (0% vs 9.2% in controls, P = 0.047). In addition, HLA-A*26 was probably an induction marker, as its allelic frequency was significantly higher among NPC patients than among controls (P = 0.003) and among NPC patients than among at-risk family members (P = 0.067). Logistic regression analysis of the joint effect of selected HLA specificities showed that HLA-A*26 and HLA-A*30 were co-associated and have an important effect on NPC risk. Despite the small size of our cohort, we showed that HLA-A*26-A*30 and HLA-DRB1*10 might be predictive markers for NPC screening of Tunisian families with a high risk of NPC.

Natural evolution of hepatitis C virus infection in hemodialysis Tunisian patients and CTLA-4 SNP's.

AIM: To analyze the polymorphisms of CTLA-4 gene involved in the response against hepatitis C virus (HCV) infection. METHODS: We recruited 500 hemodialysed patients from several hemodialysis centers, all HCV-antibody positive, spread over different regions of Tunisia, as part of a national survey in 2008 conducted in the laboratory of immunology at the Charles Nicolle hospital Tunisia, classified into two groups G1 (PCR+) and G2 (PCR-) according to the presence or absence of viral RNA. Of these patients, 307 were followed prospectively on a viral molecular level over a period from 2002 to 2008, divided into two groups based on the persistence and viral clearance. PCR-RFLP was performed for the analysis of SNPs (+49) A/G and (+6230) G/A CTLA-4 for these 500 patients and 358 healthy controls. RESULTS: Analysis of clinical and virological characteristics of our cohort suggests a nosocomial infection in our hemodialysed patients with transfusion history as a primary risk factor and a predominance of genotype 1b. The haplotype analysis revealed an increase of frequencies of GG (+49)/(CT60) CTLA-4 in the entire patients group compared to controls (P = 0.0036 and OR = 1.42; 95%CI: 1.12-1.79, respectively). This haplotype is therefore associated with susceptibility to HCV infection. CONCLUSION: Our study suggests a possible role of CTLA-4 polymorphisms in the outcome of HCV infection in the Tunisian hemodialysed population.

Vascular endothelial growth factor genetic polymorphisms and susceptibility to age-related macular degeneration in Tunisian population.

PURPOSE: Three VEGF SNPs (-2578) C/A, (+405) G/C and (+936) C/T were investigated in Tunisian exudative AMD patients in order to determine their association with the disease susceptibility and their influence to intravitreal bevacizumab therapy response. METHODS: 145 AMD patients and 207 age-matched controls were included. 68 patients were treated with intravitreal bevacizumab. SNPs genotyping were performed using direct sequencing. The serum VEGF was assayed by ELISA (R&D). RESULTS: The (+405) CC and (+936) TT genotypes were higher in AMD patients than in controls (p = 5 × 10(-6) and p = 0.021, respectively). The mean plasma levels of VEGF were statistically higher in AMD patients (84.22 pg/ml) than in controls (15 pg/ml). Three months after bevacizumab treatment, 52 patients (85.6%) were classified as good responders (GR) and 16 (14.4%) as poor responders (PR). The mean plasmatic-VEGF levels in GR patients was higher (86.61 ± 80.30 pg/ml) than in PR patients (47.12 ± 45.74 pg/ml) (p = 0.086). The patients with genotype homozygous TT (+936) would be PR compared to those carrying CT and CC genotypes. Whereas, those with AA (-2578) genotype would be GR compared with others genotypes (p = 0.014; p = 0.042 respectively). CONCLUSIONS: Our results show that VEGF genetic variants may contribute to the susceptibility to neovascular AMD in Tunisian patients.

CD86 +1057G>A polymorphism and susceptibility to acute kidney allograft rejection.

INTRODUCTION: CD86 is a costimulatory molecule that participates in the regulation of T-cell lymphocytes activation. Thus, we examined a genetic marker on the CD86 gene in kidney transplant outcome. MATERIALS AND METHODS: In our retrospective study, 168 kidney allograft recipients were genotyped by direct sequencing. Patients were classified into 2 groups of 29 human leukocyte antigen (HLA)-identical haplotype allograft recipients and 139 recipients showing one or more mismatches in the HLA haplotype. Forty-five patients (26.8%) developed at least 1 acute rejection (AR) episode, 7 in the first and 38 in the second group. RESULTS: Acute rejection was associated with the presence anti-HLA antibodies before transplantation (P = .03). The AA genotype and A allele at position +1057 in the CD86 gene were more frequent in patients without AR (9.75% and 28.5%, respectively) compared with those showing an AR (2.22% and 23.3%, respectively). This difference was statistically significant in the anti-HLA-positive recipients, as AA frequency was 31.3% in non-AR patients and zero in AR ones (P = .04) and A allele frequency was 46.9% and 20.8%, respectively (P = .04). Patients bearing AA genotype reached a higher graft survival time (9.84 years) than those carrying GA (8.21 years, P = .32) or GG (7.61 years, P = .72) genotypes. CONCLUSIONS: These results suggest that AA genotype and A allele of CD86 +1057G>A polymorphism may confer a protection against acute kidney allograft rejection in Tunisian patients.

Interleukin-18 gene polymorphisms in tunisian patients with inflammatory bowel disease.

AIM: Interleukin (IL)-18 can regulate the Th2-mediated immune response and it may be involved in the pathogenesis of Th1 and Th2 chronic inflammatory diseases. This study sought to detect a possible association between two single nucleotide polymorphisms (SNPs) (-137G/C and -607C/A) in the IL-18 gene promoter region and susceptibility to inflammatory bowel disease (IBD) including Crohn's disease (CD) and ulcerative colitis (UC) in the Tunisian population. METHODS: The (-137G/C and -607C/A) IL-18 polymorphism was analyzed in 105 patients with CD, 59 patients with UC, and 100 controls using the sequence-specific polymerase chain reaction method. RESULTS: The distribution of allele and genotype frequencies illustrate that the -137G/G genotype frequency was significantly higher in UC than in controls (p value corrected (pc) = 0.038). On the other hand, we found a statistically significant association (pc = 0.033) between genotype AA of the IL-18 gene promoter (-607C/A) polymorphism in UC patients and the distal localization of the lesions. In CD, no significant differences were observed at positions -607 and -137. The analysis of IBD patients according to clinical behavior revealed no difference. CONCLUSION: The two SNPs at position -607 (C/A) and -137 (G/C) in the promoter region of the IL-18 gene was associated with the development of UC but not CD, providing a strong support for an IBD susceptibility gene in the region surrounding IL-18. It remains to be determined precisely how the IL-18 alleles influence the pathogenesis of IBD.

[IL1/IL1 Ra, CTLA-4 and Apo1/Fas genes polymorphisms and susceptibility to IgA nephropathy in Tunisian patients]. / Polymorphismes des gènes de l'IL1/IL1 Ra, CTLA-4 et Apo1/Fas et susceptibilité à la néphropathie à IgA chez des patients Tunisiens.

BACKGROUND: The IgA nephropathy (IgA-N) is considered the most common form of primary glomerulonephritis and its pathogenic mechanisms are very complex. The study of several genes which encode for immunoregulator molecules in inflammatory and immunological responses during the disease, allowed to describe some number of polymorphisms would be involved in the molecular expression, the road marking, the synthesis and\or the binding to the receptors. So an abnormality of the molecular function associated with its polymorphism would be suggested in the genetic predisposition to the disease. AIM: To determine interleukin 1 (IL1), interleukin1 receptor antagonist (IL1 Ra), CTLA-4 and Apo1/Fas genes polymorphisms frequencies in IgA-N in order to estimate the impact of these polymorphisms in the disease susceptibility. METHODS: The polymorphism of a single nucleotide (SNP) at (-889) IL1 a of 21 IgA-N patients and 100 healthy blood donors, as controls, was studied by PCRSSP. The SNPs of the IL1 ß (+3954), CTLA-4 (+49) and l'Apo1/Fas were analyzed by PCR RFLP and finally the polymorphism of the IL1 Ra gene was determined by a PCR VNTR (variable number tandem repeat). RESULTS: Investigation of IL1a/ß and Apo1/Fas polymorphisms showed no differences in genotypes and alleles frequencies between IgA-N patients and controls. However, genotype AA of CTLA-4 exon1 (+49) was significantly higher in patients (47.62%) than in controls (9.1%) p<0.001. Nevertheless, the clinical, histological and biological characteristics of IgA-N were similar in AA CTLA-4 genotype patients compared to AG or GG genotype patients. We fund also, a significant increased frequency of 1/1 IL1 Ra genotype in IgA-N patients (95.24%) compared to controls (54%) (p<0.001) (p<0.001). CONCLUSION: We conclude that the susceptibility to IgA-N seems to be associated with the presence of CTLA-4 AA and IL1 Ra 1/1 genotypes in Tunisian population. However, the lack of association between IL1 a/ß and Apo1/fas genes polymorphisms should be further investigated by large population based studies.

Lymphoid tyrosine phosphatase R620W variant and inflammatory bowel disease in Tunisia.

AIM: To assess the possible association between PTPN22 (R620W) gene polymorphism and inflammatory bowel disease (IBD). METHODS: One hundred and sixty-four patients with IBD [105 Crohn's disease (CD) and 59 ulcerative colitis (UC)] and 100 healthy controls were recruited. Genotyping of the PTPN22 gene 1858C-->T polymorphism was performed by restriction fragment length polymorphism-polymerase chain reaction with RsaI digestion. RESULTS: The genotypic and allelic frequencies of (R620W) PTPN22 gene polymorphism reveal a significant association of the PTPN22 620-W allele with IBD, compared to the healthy control group (OR: 17.81, 95% CI: 4.18-21.86, P = 0.00001). Nevertheless, no difference in this polymorphism was found between CD and UC patients. No significant association was found between the frequencies of genotypes of the PTPN22 gene with either the clinical features such as sex, age, age at disease onset, and extent of colitis, or the production of serological markers (anti-Saccharomyces cerevisiae antibody in CD and perinuclear anti-neutrophil cytoplasmic antibody in UC). CONCLUSION: These observations confirm the association of IBD susceptibility with the PTPN22 1858T (620-W) allele in Tunisian patients.

Role of genetic polymorphisms in factor H and MBL genes in Tunisian patients with immunoglobulin A nephropathy.

The molecular mechanisms of IgA nephropathy (IgAN) remain poorly understood. Several different polymorphic genes have been investigated in order to demonstrate their possible association with this disease. It is evident that mainly alternative and lectin pathways complement activation and play an important role in renal injury of IgAN. This study was conducted to determine eventual deficiencies of factor H in the SCR20 gene region and to look for a possible association between the polymorphism (+54) exon 1 of the MBL gene and the predisposition in Tunisian patients with IgAN. We then evaluated the effects of these FH mutations and/or this MBL polymorphism on nephropathy susceptibility and progression. Polymorphism A/B (+54) in the exon1 of the MBL gene and analysis within the C-terminal domain of the protein SCR20 in the exon 22 of the factor H (FH) gene were conducted in 36 sporadic IgAN Tunisian patients and 117 age and gender matched healthy subjects recruited from blood donors, by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing respectively. The analysis of the Gly54Asp (+54) mutation of the MBL gene according to the criteria of gravity of the IgAN reveals that the patients with genotype AB present more frequently with end-stage renal disease (ESRD) compared with those of genotype AA [OR: 8, CI (1.74-54.49), P = 0.019]. Moreover, the variant allele B was statistically more frequent than the allele A in patients with an association with initial arterial high blood pressure, ESRD and class V of the Haas classification compared to those without this association (P = 0.009). The direct sequencing of exon 22 (SCR 20) of FH gene did not reveal any abnormal mutational deficiency for this factor in all patients and controls. The data did not support the hypothesis that FH is a susceptibility factor for the IgAN. However the data did show there was an association between AB (+54) exon1 MBL genotype and severe sporadic forms of this disease in Tunisian patients. Because of the small number of subjects studied, a much larger cohort of IgAN patients with varying severity of the disease and its progression would seem necessary to confirm these findings.

Atypical hemolytic uremic syndrome and mutation analysis of factor H gene in two Tunisian families.

We carried out a protein and genetic investigation of the factor H gene mutations within two families presenting with a diagnostic suspicion of atypical hemolytic uremic syndrome (aHUS). The results within the patients of the first family revealed a factor H-deficiency. Direct sequencing allowed the detection of a 4-nucleotide deletion in the factor H gene. This deletion was found as the homozygote form in the proband and as the heterozygote form in the parents. Protein and functional analyses of the complement system were normal in all members of the second family. However, the molecular investigation for the father showed the presence of an amino acid substitution in the FH gene. Unfortunately, his two affected children died without being investigated for mutations. The functional consequences of these abnormal proteins are still to be demonstrated.

Association of Fas/Apo1 gene promoter (-670 A/G) polymorphism in Tunisian patients with IBD.

AIM: To detect a possible association between the polymorphism of the (-670 A/G) Fas/Apo1 gene promoter and susceptibility to Crohn's disease (CD) and ulcerative colitis (UC) in the Tunisian population. METHODS: The (-670 A/G) Fas polymorphism was analyzed in 105 patients with CD, 59 patients with UC, and 100 controls using the polymerase chain reaction restriction fragment length polymorphism method. RESULTS: Significantly lower frequencies of the Fas -670 A allele and A/A homozygous individuals were observed in CD and UC patients when compared with controls. Analysis of (-670 A/G) Fas polymorphism with respect to sex in CD and UC showed a significant difference in A/A genotypes between female patients and controls (P corrected = 0.004 in CD patients and P corrected = 0.02 in UC patients, respectively). Analysis also showed a statistically significant association between genotype AA of the (-670 A/G) polymorphism and the ileum localization of the lesions (P corrected = 0.048) and between genotype GG and the colon localization (P corrected = 0.009). The analysis of inflammatory bowel disease patients according to clinical behavior revealed no difference. CONCLUSION: Fas-670 polymorphism was associated with the development of CD and UC in the Tunisian population.

Distribution of HLA-B*27 subtypes in Tunisians and their association with ankylosing spondylitis.

OBJECTIVE: The human leukocyte antigen HLA-B27 is a class I antigen of the major histocompatibility complex strongly associated with ankylosing spondylitis (AS) and other related spondyloarthropathies (SpAs). The mechanism of this association remains unknown. HLA-B27 is a serologic specificity that represents a family of at least 25 different HLA-B27 alleles (2701-2725). These alleles are closely related by nucleotide sequence homology, but differ in ethnic distribution. The purpose of the present study is to investigate the distribution of HLA-B27 alleles in healthy controls and in patients with ankylosing spondylitis (AS). METHODS: We selected 160 HLA-B27-positive individuals (39 controls and 121 patients with ankylosing spondylitis). Typing of HLA-B27, and Cw alleles were performed by polymerase chain reaction amplification with sequence specific primers (PCR-SSP), and by serological typing (microlymphocytotoxicity). RESULTS: Seven B27 subtypes were identified: B*2702, 03, 04, 05, 07, 09 and B*2714. The distribution of these alleles in the population of patients was B*2702 (47.1%) and B*2705 (47.1%). These subtypes were also detected in 16 (41%) and 16 (41%), respectively of the 39 control subjects. HLA-B*2707 was detected in 4 (3.31%) patients and in 3 (7.6%) controls. B*2704, 09 and B*2714 were relatively rare and were detected in one subject each. No significant differences were noticed in the frequencies and distribution of HLA-B27 alleles between patients and controls. CONCLUSIONS: Our results show a restricted number of HLA B27 subtypes associated with AS. B*2702 and B*2705 were equally common in patients and controls. The most prominent B27/Cw haplotypes in the patient groups and controls were B*2702/Cw02022 and B*2705/Cw02022.