Impact of a genetic polymorphism of the interleukin-1 receptor antagonist on technique survival in peritoneal dialysis patients.

BACKGROUND/AIMS: There is a clear association between one allele of the interleukin-1 receptor-antagonist gene (IL-1RN) and inflammatory diseases in which IL-1 is implicated. We evaluated patient survival and technique survival of peritoneal dialysis (PD) patients, while analyzing independent risk factors, in a PD program. We also tested the association between IL-1RN polymorphism, patient survival and technique survival. METHODS: We retrospectively evaluated 129 Japanese CAPD patients undergoing initial treatment in eight centers in Japan. Using PCR, IL-1RN genotype and allele frequencies were determined, and clinical and biochemical variables were recorded at the start of PD. The relation of patient survival or technique survival with IL-1RN polymorphism and those variables was analyzed with a multivariate Cox's proportional-hazard model. RESULTS: The frequencies of IL-1RN*1/IL-1RN*1 and IL-1RN*1/IL-1RN*2 genotypes were 84.5 and 15.5%, respectively. Median patient survival was 37.0 months, and overall patient survival was 92.8 and 87.9% at 2 and 5 years, respectively. Age, cardiovascular disease and serum albumin were found to be independent predictors of patient survival. Median technique survival was 32 months. PD failure occurred in 37 patients, with technique survival rates of 92.0 and 72.7% at 2 and 5 years, respectively. Serum albumin, peritonitis and the presence of the IL-1RN*2 genotype were found to be independent predictors of technique survival. CONCLUSION: Serum albumin was the strongest predictive factor for mortality and technique failure in PD. Technique failure was also affected by IL-1RN polymorphism in this patient population.

Evaluation of a new efficient procedure for single-nucleotide polymorphism genotyping: tetra-primer amplification refractory mutation system-polymerase chain reaction.

Tetra-primer amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) is a new efficient method for single-nucleotide polymorphism (SNP) genotyping. To determine the optimal conditions for ARMS-PCR we attempted to genotype ten SNPs. DNA was extracted from the peripheral blood of 168 unrelated healthy Japanese volunteers. Two problems inhibited uniform efficiency of the amplification of three bands. The first problem was the lower amplification efficiency of the shorter and allele-specific products compared with the largest product. This phenomenon was overcome by increasing the relative concentration of the inner primers. The second problem was non-specific amplification of the shorter products. To reduce the amplification of these non-specific bands, adjusting any one of the following PCR conditions was effective: i) reducing the ratio of the inner primer concentration relative to that of the outer primers; ii) increasing the annealing temperature for the initial 5-10 cycles; iii) hot start PCR. With these procedures all ten of the SNPs were successfully genotyped. Our present data may be useful in the further application of tetra-primer ARMS-PCR to SNP genotyping.

Association of the -173 G/C polymorphism of the macrophage migration inhibitory factor gene with ulcerative colitis.

BACKGROUND: Macrophage migration inhibitory factor (MIF) is a proinflammatory cytokine and has been shown to be involved in the development of chronic murine colitis. In the +173 G/C polymorphism of the MIF gene, the presence of C creates the binding motif of activator protein 4. This study explored the association of this polymorphism with ulcerative colitis (UC). METHODS: Genotyping was carried out, with a tetra-primer polymerase chain reaction (PCR) method, for 659 DNA specimens from 438 healthy volunteers and 221 patients with UC. Genotype distribution between cases and controls and the association of patients' genotypes with clinical parameters were statistically evaluated. RESULTS: No significant difference in genotype distribution was found between UC patients and healthy controls. However, when the relation of the C/C genotype to clinical parameters in UC patients was evaluated by Fisher's exact test, it was found that the frequency of the C/C genotype was higher in patients with pancolitis type than in those with other types restricted to the distal or left-sided colon (odds ratio [OR], 10.781; 95% confidence interval [CI], 1.342-86.619; P = 0.0074). CONCLUSIONS: These data suggest that the MIF -173 G/C polymorphism may be related to the extent of disease in UC in a Japanese population.

Association of functional polymorphisms of matrix metalloproteinase (MMP)-1 and MMP-3 genes with colorectal cancer.

Matrix metalloproteinase (MMP)-1 and MMP-3 genes are associated with tumor cell invasion and metastasis with their promoter polymorphisms influencing the level of transcription. Our study explored the association of these polymorphisms with colorectal cancer risk in a Japanese population. DNA was extracted from peripheral blood of 101 patients with colorectal cancer and 127 age- and gender-matched healthy volunteers. Genotyping was carried out using PCR-RFLP and direct sequencing. In the MMP-1 gene polymorphism, the frequency of the 2G/2G genotype that is associated with higher enzyme activity was significantly increased in colorectal cancer patients when compared to controls (p = 0.0067; OR = 2.077; 95% CI = 1.221-3.534). With regard to the MMP-3 polymorphism, unexpectedly, the frequency of the 6A/6A genotype causing lower enzyme activity was significantly increased in patients (p = 0.0129; OR = 2.110; 95% CI = 1.165-3.822). Because the loci for the 2 MMP genes are closely linked, we examined linkage disequilibrium between the 2 loci using expectation-maximization algorithm. We found that the 2 loci were in linkage disequilibrium and that 2G-6A haplotype was significantly increased in patients compared to controls (p = 0.0010; OR = 1.949; 95% CI = 1.305-2.911). Our present data suggest that the MMP-1 and MMP-3 promoter polymorphisms may be associated with a colorectal cancer susceptibility in Japanese.

Simple genotype analysis of the Asp299Gly polymorphism of the Toll-like receptor-4 gene that is associated with lipopolysaccharide hyporesponsiveness.

A nonsynonymous single nucleotide polymorphism (Asp299Gly) in the Toll-like receptor-4 (TLR-4) gene affects the responsiveness to lipopolysaccharide in humans. To analyze this important polymorphism more efficiently, we developed a simple polymerase chain reaction (PCR) restriction length fragment polymorphism (RFLP) assay and examined the Asp299Gly allele frequency in a Japanese population. The PCR primer was designed with 1- or 2-bp mismatches, creating the recognition sequence for restriction enzyme BsaBI or BstXI, allowing RFLP analysis of the digested products. Genotyping was carried out with this assay for 275 DNA specimens from 107 healthy volunteers and 168 patients with various diseases, including ulcerative colitis (n = 86). The Asp299Gly allele of the TLR-4 gene was not detected in any of the specimens, suggesting that it is very rare in Japanese.