Analysis of the first intron of TNFB gene by NcoI RFLP in Koreans

Allelic frequencies and patterns of single-nucleotide polymorphisms in candidate genes for asthma and atopy in Iceland

Numerous asthma and atopy loci have been reported in studies demonstrating associations of the asthma-related phenotypes atopy, elevated IgE levels, and bronchial hyperresponsiveness with alleles of microsatellite markers and single-nucleotide polymorphisms (SNPs) within specific cytokine/chemokine and IgE-regulating genes. Although the studies reporting these observations are compelling, most of them lack statistical power. We assessed the nature, pattern, and frequency of SNPs in 24 candidate genes in Iceland and looked for associations with asthma and atopy. We identified 42 SNPs with an average minor allele frequency of 20.3% (asthma) and 20.7% (control). Twenty SNPs (48%) were within coding sequences and 90% of those led to a predicted change in protein sequence. No differences were detected in the allelic frequencies of SNPs in any of these candidate genes between control subjects and the patients with atopic asthma. Moreover, linkage analysis that included 269 patients with atopic asthma uncovered no evidence of linkage to markers associated with these genes. We conclude that this study has failed to produce evidence in support of the notion that variations within these 24 candidate atopy and asthma genes significantly influence the expression of the atopic asthmatic phenotype or contribute to the susceptibility of atopic asthma.

Polymorphisms within the tumor necrosis factor locus and prevalence of coronary artery disease in middle-aged men

Tumor necrosis factor (TNF) is an important cytokine in the inflammation process of atherosclerosis and is also involved in lipid metabolism. Two biallelic polymorphisms within TNF gene locus-TNFA at the position -308 in the promoter region of the TNF gene and TNFB in the first intron of the lymphotoxin-alpha (LT-alpha) have been reported to be associated with TNF production and with susceptibility to inflammatory diseases. We studied the association of these polymorphisms within the major histocompatibility complex (MHC) III region with coronary atherosclerosis and its manifestations. The autopsy series comprised 700 Caucasian Finnish men, aged 33-70 years (The Helsinki Sudden Death Study). Coronary stenosis and surface area of atherosclerotic changes (fatty streaks, fibrous plaques, complicated lesions and calcification) were measured and the presence of myocardial infarction and coronary thrombosis recorded. TNFA and TNFB genotypes were determined by the PCR-RFLP technique. The allele frequencies were TNFA1/TNFA2=0.88/0.12 and TNFB1/TNFB2=0.30/0.70. There was a strong linkage disequilibrium between the two polymorphisms. There were no differences in coronary stenosis and in the frequency of old or recent myocardial infarction or coronary thrombosis between men with different genotype status in either locus. Men with TNFA22 or TNFB11 genotype tended to have more fibrous lesions and calcification in their coronary arteries. TNFA and TNFB polymorphisms are unlikely to contribute to progression of atherosclerosis in a way clinically important.

Relation of a TNF gene polymorphism to severe sepsis in trauma patients

OBJECTIVE

To investigate the relation of the biallelic Nco1 restriction fragment length polymorphism in the first intron of the tumor necrosis factor (TNF) beta gene with the development of severe sepsis in multiply injured patients.

SUMMARY BACKGROUND DATA

The biallelic Nco1 polymorphism of the TNFbeta gene has been described to be associated with autoimmune diseases and with the mortality rate in severe sepsis. Therefore, the Nco1 polymorphism may be associated with the clinical finding that despite comparable risk factors, posttraumatic sepsis develops in some patients but not others.

METHODS

The study group consisted of 110 patients with severe blunt trauma (Injury Severity Score > or = 17). Typing of each patient for the biallelic Nco1 polymorphism was performed by analyzing restriction fragments of an Nco1-digested DNA fragment obtained using polymerase chain reaction. Genotypes were then related to the occurrence of severe posttraumatic sepsis and TNFalpha serum concentrations.

RESULTS

Fifty-seven patients showed an uncomplicated posttraumatic recovery, and severe sepsis developed in 53 patients. The overall allele frequency (TNFB1 0.29, TNFB2 0.71) and genotype distribution (TNFB1 homozygous 7.3%, TNFB1/TNFB2 42.7%, TNFB2 homozygous 50%) were in agreement with the distribution in healthy volunteers. Genotype distribution in patients with an uncomplicated clinical course was significantly different from that in patients with severe posttraumatic sepsis. Development of severe posttraumatic sepsis was significantly increased in patients homozygous for the allele TNFB2. In patients with severe posttraumatic sepsis, TNFalpha serum concentrations were significantly higher in TNFB2-homozygous individuals compared with heterozygous and TNFB1 -homozygous individuals. The age- and injury-matched odds ratio for the homozygous TNFB2 genotype compared with the heterozygous genotype was 5.22 (p = 0.007, 95% confidence interval 1.6 to 17.9).

CONCLUSIONS

In multiply injured patients, the Nco1 polymorphism within the TNFbeta gene is associated with the development of severe posttraumatic sepsis and with increased TNFalpha serum levels when severe sepsis has occurred. This suggests a genetic determination of the individual inflammatory response after infection or tissue damage, which significantly influences susceptibility to severe nosocomial infections.