Interleukin-18 and its three gene polymorphisms relating to allergic rhinitis.

The study aimed to examine an association of three different single nucleotide polymorphisms (SNPs) of the IL-18 gene (-607 C/A, -137 G/C and -133 C/G) on chromosome 11q22 with allergic rhinitis (AR). Genotyping for the SNPs was performed using 539 patients with AR and 312 healthy control volunteers. Positivity to the skin prick test for the fungus Alternaria sp. in patients with AR, and IgE levels according to particular genotypes of selected SNPs, were also determined. There were no significant differences in the distribution of single IL-18 alleles or genotypes between controls and AR patients. However, frequencies of combined IL-18 genotypes arising from combinations of the three common polymorphisms (-607, -137 and -133) were significantly different between both groups (P = 0.009, P (corr) < 0.05, OR = 5.35, 95% CI: 1.9-15.2). There was a marginally significant association of the IL-18-607 variant with IgE levels (P = 0.05) in patients, but not in the case of the other SNPs. Patients allergic to Alternaria, but not those allergic to other antigens, showed a significant association with the IL-18-607 polymorphism (P = 0.0037, P (corr) < 0.05). Results suggest that IL-18 gene variants may be one of the factors participating in the pathogenesis of AR or its intermediary phenotypes.

Association study of promoter polymorphisms within the NOS3 gene and allergic diseases.

BACKGROUND: Nitric oxide (NO) is an important mediator of physiologic and pathologic processes in the airways. On this basis, we hypothesized that polymorphisms in the NOS3 gene could be associated with the disease process. METHODS: Two promoter variants (-786C/T and -691C/T) were examined in a Caucasian Czech population of allergic patients [n = 671, with a subgroup of asthmatics (n = 305)] and healthy controls (n = 334) using PCR-RFLP analyses. RESULTS: NOS3 -786C/T and -691C/T were not associated with allergic diseases or asthma. However, the -786 variant was significantly associated with asthma in men (p < 0.01, p(corr) < 0.05) but not in women. NOS3 -691C/T was found to be in strong linkage disequilibrium with -786C/T, and the distribution of combined genotypes was marginally different between the asthmatic and control men. CONCLUSION: Our results suggest that NOS3 gene variants may be one of the factors that participate in the pathogenesis of asthma in men.

Haplotype analysis of the RAGE gene: identification of a haplotype marker for diabetic nephropathy in type 2 diabetes mellitus.

BACKGROUND: Diabetic nephropathy (DN) represents a devastating complication of diabetes. Family clustering, heterogeneity in the onset and progression and results of segregation studies indicate that susceptibility to DN is a complex trait. METHODS: Common single nucleotide polymorphisms in the RAGE (receptor of advanced glycation end-products) gene (-429T/C, -374T/A, G82S, 1704G/T, 2184A/G and 2245G/A) were studied in the association study comprising 605 Caucasian subjects by means of haplotype analysis in order to identify an eventual haplotype marker for DN in type 2 diabetes. Haplotypes were constructed computationally; frequencies were compared among groups of subjects with type 2 diabetes (DM) and DN, diabetics without DN and non-diabetics. Survival analysis was carried out to ascertain whether certain RAGE haplotypes influence onset of DN in type 2 diabetics. RESULTS: Significant differences in haplotype frequencies among DM + DN vs DM non-DN and non-DM groups were found (P = 0.0007 and 0.0013, respectively; permutation test). Frequency of the RAGE(2) haplotype containing minor alleles in positions -429 and 2184 (CTGGGG) in the DN group was significantly higher than in the two control groups (21.7% vs 12.8% and 13.8%, both P(corr)<0.003; two-tail Fisher exact test); odds ratios 1.65 [95% confidence interval (CI): 1.08-2.50; P = 0.020] and 1.79 (95% CI: 1.22-2.62; P = 0.003), respectively. In survival analysis, duration of diabetes until the onset of DN (e.g. appearance of persistent proteinuria) was significantly different among RAGE(2) diplotype groups (P<0.05); median DN-free interval was 9.6 years in RAGE(2) +/+ homozygotes, 15.2 years in +/- heterozygotes and 17.0 years in the -/- combination. CONCLUSIONS: The RAGE(2) haplotype is associated with DN in type 2 diabetics and with earlier DN onset and, thus, can be regarded a marker for DN.

Analysis of the interleukin-6 gene promoter polymorphisms in Czech patients with chronic periodontitis.

BACKGROUND: Chronic periodontitis is an inflammatory disease, which is a major cause of tooth loss. The proinflammatory cytokines interleukin-1 (IL-1) and interleukin-6 (IL-6) are key regulators of the host response to microbial infection and major modulators of extracellular matrix catabolism and bone resorption. The purpose of this study was to investigate the associations of chronic periodontitis with IL-6 gene polymorphisms (at positions -597 [G/A], -572 [G/C], and -174 [G/C]). METHODS: We analyzed allele, genotype, and haplotype distributions of the IL-6 promoter variants in a case-control study involving 148 patients with chronic periodontitis and 107 unrelated controls. RESULTS: Our results showed significant differences in the distributions of alleles and genotypes of the IL-6 (-572 G/C) polymorphism between patients and the control population (chi2 = 10.393, P= 0.001, P(corr) < 0.01). The difference was due to the underrepresentation of the -572 G/C heterozygotes in patients (6.1%) compared to controls (19.6%). Although no variant "CC" homozygotes were detected in our cases and controls, heterozygosity protected against chronic periodontitis, representing a 73% reduction of risk (odds ratio [OR] = 0.27, 95% confidence interval: 0.12-0.61) compared to wild-type homozygotes. However, there were no significant differences in genotype or allele frequencies between both groups for IL-6 -597 G/A and -174 G/C polymorphisms. CONCLUSION: This study is the first, to our knowledge, suggesting that the -572 G/C polymorphism of the IL-6 gene may be one of the protective factors associated with lower susceptibility to chronic periodontitis.

Polymorphisms in angiotensinogen gene (M235T and G(-6)A) in multifactorial diseases.

The aim of the study is to compare results of three association (case-control) studies in three multifactorial disorders (essential hypertension, atopic diseases and psoriasis) with two polymorphisms of angiotensinogen gene (M235T and A(-6)G). The diseases were chosen for their multigenic base and different immunological characteristic (Th1, Th2 and Thps) and angiotensinogen gene for its pleiotropic functional effects in general adaptive reactions. In all (control as well as case) groups, tight linkage disequilibrium between the polymorphisms was found. The strength of linkage (%) differed among the group. The direction of the linkage is identical in all groups (T is combined with A, M is combined with G). In hypertensive-normotensive study, only Hardy-Weinberg disequilibria were found, especially in men. No case-control differences were found for either single alleles or for allelic concurrence of both polymorphisms. In atopy-control study, marginal case-control differences in single allele distribution of both polymorphisms were found, but only in women. In psoriasis-control study, the only significant case-control difference was found,when genotypes MTAA and MTGG were present in 2/136 psoriatic patients vs. 20/142 control subjects (OR 0.1, 95% confidence interval 0.02-0.42, P=0.00015). The frequent polymorphisms in pleiotropic genes can form different formulae of genotype distribution in different multigenic diseases according to their contribution to the onset and/or progression of the disease in some evolutionary consequences.