Svatava Tschöplová

Genetic risk factors for diabetic nephropathy on chromosomes 6p and 7q identified by the set-association approach.

Aims/hypothesisIn the present study we investigated potential associations of a set of 45 single nucleotide polymorphisms (SNP) in 20 candidate genes on eight chromosomes with diabetic nephropathy (DN) in type 2 diabetes mellitus. We aimed to compare two methodological approaches suitable for analysing susceptibility to complex traits: single- and multi-locus analyses.Materials and methodsThe study comprised a total of 647 subjects in one of three groups: diabetes with or without DN, or no diabetes. Genotypes were detected by PCR-based methodology (PCR only, PCR plus RFLP, or allele-specific PCR). Haplotypes were inferred in silico. Set association (tested using SUMSTAT software) was used for multilocus analysis.ResultsAfter correction for multiple comparisons, only one SNP, in the gene encoding the receptor of advanced glycation end products, AGER 2184A/G (gene symbol formerly known as RAGE) showed a significant association with DN (p = 0.0006) in single-locus analysis. In multi-locus analysis, six SNPs exhibited a significant association with DN: four SNPs on chromosome 6p (AGER 2184A/G, LTA 252A/G, EDN1 8002G/A and AGER -429T/C) and two SNPs on chromosome 7q (NOS3 774C/T and NOS3 E298D), omnibus p = 0.033. Haplotype analysis revealed significant differences between DN and control groups in haplotype frequencies on chromosome 6 (p = 0.0002); however, there were no significant difference in the frequencies of the NOS3 haplotypes on chromosome 7. Logistic regression analysis identified SNPs AGER 2184A/G and NOS3 774C/T, together with diabetes duration and HbA1c, as significant predictors of DN. Testing for interactions between SNPs on chromosomes 6 and 7 did not provide significant evidence for epistatic interaction.Conclusions/interpretationUsing the set-association approach we identified significant associations of several SNPs on chromosomes 6 and 7 with DN. The single- and multi-locus analyses represent complementary methods.

Genotype association of C(-735)T polymorphism in matrix metalloproteinase 2 gene with G(8002)A endothelin 1 gene with plaque psoriasis

Background: Excessive angiogenesis is one of the characteristic features of psoriasis. Objective: To determine the possible genetic background of neo-angiogenesis in plaque psoriasis, frequent polymorphisms in matrix metalloproteinase 2 (MMP-2) and endothelin 1 (ET-1) genes were studied. Methods: The case group (n = 119) included patients with plaque psoriasis, aged 44 ± 15 years. The age of onset of psoriasis was 27 ± 11 years. The control group (n = 184) consisted of healthy subjects without any individual history of psoriasis, aged 37 ± 15 years. C(-735)T MMP-2 and G(8002)A ET-1 polymorphisms were determined by PCR reaction with subsequent restriction analyses. Results: A significant difference in genotype distribution of C(-735)T MMP-2 between psoriatic and control patients was found (pcorr = 0.008). Two associated genotypes (CCGG and CTGG) of the two polymorphisms were significantly less frequent in psoriatic patients (pcorr = 0.03 and pcorr = 0.008, respectively). Conclusion: The results seem to reflect a different susceptibility of MMP-2 as well as of some associated MMP-2 and ET-1 genotypes to psoriasis.

Polymorphisms in inflammation genes (angiotensinogen, TAP1 and TNF-β) in psoriasis

Abstract This study focused on the association between plaque psoriasis and polymorphisms of several inflammation genes. Included in the study were 142 Caucasian (Czech) patients with plaque psoriasis and 141 healthy subjects. The genotypes of the polymorphisms in angiotensinogen [M235T ATG, A(-6)G ATG], in transporters associated with antigen processing TAP1 ( TAP1*0101, TAP*02011 and TAP1*0301 ) and in lymphotoxin α (TNFβ) (NcoI in intron 1) were detected by polymerase chain reaction-based methods and restriction enzyme analysis. An increase in B1 (less frequent) allele of NcoI TNFβ polymorphism was found in psoriatic patients compared to healthy individuals (odds ratio = 1.6, 95% confidence interval 1.13–2.26, P = 0.006). A positive family history of psoriasis was associated with a higher B1 allele frequency in NcoI TNFβ ( P = 0.011). Hardy-Weinberg disequilibrium was found in TAP1 polymorphism A→G at nucleotide 1207 in psoriatic patients. A case-control difference was found in the allelic concurrence of M235T and A(-6)G ATG polymorphisms. The most frequent population genotypes MMGG, MTAG and TTAA were observed in 92% of patients vs 74% of control subjects (odds ratio 0.29, 95% confidence interval 0.14–0.60, P = 0.0003). A positive history of tonsillitis and/or tonsillectomy was associated with a higher T allele frequency of the M235T ATG polymorphism ( P = 0.037) as well as with a higher G allele frequency of the A(-6)G ATG polymorphism ( P = 0.022). Polymorphisms in proinflammatory angiotensinogen and TNFβ genes were associated with plaque psoriasis, a positive family history of psoriasis and with frequent tonsillitis in childhood.

An association of BMI with A (-6) G, M235T and T174M polymorphisms in angiotensinogen gene in essential hypertension

The aim of the study was to assess the existence of possible associations among frequent polymorphisms in angiotensinogen genes and some of the risk factors for essential hypertension, especially body mass index (BMI) and smoking. A total of 192 control subjects (aged 45.87 ± 3.0 years) and 206 patients with the essential hypertension (aged 48.71 ± 8.42 years) were compared at three angiotensinogen gene polymorphisms by considering BMI and smoking status. No significant differences in genotype and/or allelic distribution for either A (-6) G ATG, M235T or T174M polymorphisms between the hypertensive and control groups were proved. Significantly more hypertensives than control persons with BMI above 25 kg/m2 were observed (Pcorr = 0.009), independently on sex distribution. A percentage of 44.6% of smokers in the control group vs 46.0% of smokers in the hypertensive groups were found. No significant difference in concurrence of BMI above 25 kg/m2 and positive smoking status between control and hypertensive subjects was found. Statistically significant differences were found between control and hypertensive subjects when compared distributions of subjects with certain genotypes of the three examined polymorphisms considering BMI (Pcorr = 0.0002 for AA+AG of A (-6) G ATG, Pcorr = 0.01 for CC+CT of T(174)M ATG and Pcorr = 0.01 for MT+TT of M235T ATG). No functional relationship among obesity and the examined polymorphisms in vivo are known. We conclude that a different distribution of BMI could influence the results of analyses of angiotensinogen gene polymorphisms in essential hypertension-control studies.

An association of three polymorphisms in the gene coding for endothelin-1 (ET-1) in essential hypertension

Four hundred of Caucasian (Czech) normotensive (normotension was confirmed by 24-h ambulatory blood pressure monitoring) and hypertensive subjects of the age of 45-55 years were compared in three ET-1 gene (6p21.3) polymorphisms CA/CT dinucleotide repeat in Z-area, I/D (-4A/-3A) polymorphism in the promoter and Taq1 (G8002A) polymorphism in the intron 4 detected by PCR methods.The allelic length of CA/CT dinucleotide repeat polymorphism was significantly higher in hypertensive subjects (P=0.032). Allelic concurrence of I/D promoter polymorphism and Taq1 polymorphism was significantly different (P=0.008) in hypertensive vs.normotensive women (not in men). Linkage disequilibria between CA/CT and Taq polymorphisms were found both in hypertensive (P=0.008) and normotensive (P=0.02) subjects. Complex interaction among alleles inside the gene coding for ET-1 gene could participate in pathogenesis of essential hypertension.

Three novel polymorphisms in the promoter region of the TIMP-3 gene are not associated with proliferative diabetic retinopathy in type 2 diabetes mellitus.

Purpose. Tissue inhibitor of metalloproteinase-3 (TIMP-3) is a member of the TIMP family of proteins, playing a significant role in the control of extracellular matrix remodelling. TIMP-3 might play a role in the regulation of retinal neovascularization during progression of diabetic retinopathy. Recently, three novel polymorphisms (-899T/A, -915A/G and -1296T/C) in the promoter region of the TIMP-3 gene have been identified. The aim of the study was to investigate a possible association of these polymorphisms with proliferative diabetic retinopathy (PDR) in type 2 diabetes mellitus (T2DM). Methods. Genotypes were detected by polymerase chain reaction and subsequent restriction with specific endonucleases. Allele frequencies were determined in an association study comprising three groups of subjects (n = 371). Results. Linkage disequilibrium was found among the three polymorphisms (P = 0.01). Allele frequencies did not differ between neither T2DM + PDR and T2DM non-PDR subjects (P > 0.05) nor between all T2DM versus non-diabetic subjects (P > 0.05). Conclusions. Polymorphisms in the promoter region of the TIMP-3 gene were not associated with the PDR in the Caucasian T2DM patients.

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.