Are genetic polymorphisms of tumour necrosis factor alpha, interleukin-10, CD14 endotoxin receptor or manganese superoxide dismutase associated with alcoholic liver disease?

Outcomes of excessive alcohol drinkers without baseline evidence of chronic liver disease after 15 years follow-up: Heavy burden of cancer and liver disease mortality

Background

Most long-term heavy drinkers do not have clinically evident chronic liver disease (CLD). However, at any time-point, their risk of developing CLD remains unknown. We aimed to evaluate the long-term outcomes of a group of heavy drinkers, without evidence of CLD at baseline.

Methods

A cohort of 123 long-term heavy drinkers without CLD were prospectively recruited in 2002 and retrospectively followed until 2018.

Results

At baseline (2002), median alcohol consumption was 271±203g/day during 21.5±20 years, 65% being abstinent during the previous 1.75±5 months. Patients were followed for 14±3 years. During follow-up, 53% reported any alcohol intake. Alcohol consumption during follow-up associated weakly with either 1- or 6-months previous abstinence at baseline. Until 2018, progression to CLD occurred in 6%, associating with years of alcohol intake during follow-up (OR 1.15 [1.01–1.31]) and baseline alkaline-phosphatase (OR 1.05 [1.01–1.10]). During follow-up, being abstinent for at least 1 year positively associated with CLD-free survival. 27% died (55% of cancer–mostly oropharyngeal cancer, 27% of cardiovascular disease, and 9% of liver disease), with a mean age of 71 years [69–74] (10 years less than the expected in the Portuguese population). Achieving abstinence for at least 1 year positively associated with overall survival, while smoking, and hepatic steatosis at baseline associated negatively.

Conclusion

Long-term heavy drinkers seemed to have a decreased life expectancy compared with the overall Portuguese population. Cancer was the main cause of death. Our results suggest that progression to CLD depends mostly on continued alcohol intake. Alcohol abstinence, even if temporary, seems to decrease the risks of CLD and mortality.

A two gene-based risk score predicts alcoholic cirrhosis development in males with at-risk alcohol consumption

Background

Alcoholic cirrhosis represents 1% of all cause-of-deaths worldwide. Its incidence is higher in males and results from the combination of environmental and genetic factors. Among all the genetic determinants of alcoholic cirrhosis, the patatin-like phospholipase domain protein 3 (PNPLA3) rs738409 represents the most widely validated determinant. Recent cross-sectional studies on alcohol abusers identified transmembrane-6 superfamily member 2 (TM6SF2) rs58542926, membrane bound O-acyltransferase domain containing 7 (MBOAT7) rs641738, and cluster of differentiation 14 (CD14) rs2569190 as new genetic risk factors for alcoholic cirrhosis. We aimed to develop a gene-based risk score to predict the incidence of alcoholic cirrhosis in males with at-risk alcohol consumption.

Materials and methods

A total of 416 male at-risk alcohol drinkers were retrospectively examined. The association between alcoholic cirrhosis incidence and PNPLA3, CD14, TM6SF2, and MBOAT7 variants was tested. Age at onset of at-risk alcohol consumption, age, and body mass index (BMI) were included as covariates to determine the prediction score for alcoholic cirrhosis incidence by evaluating time-dependent receiver operating characteristic curves.

Results

We found that PNPLA3, CD14, and TM6SF2 were associated with alcoholic cirrhosis prevalence. PNPLA3 and CD14 were also associated with its incidence. The best predictive score formula was (age at onset of at-risk alcohol consumption × 0.1) + (number of CD14 allele T) + (number of PNPLA3 allele M) + (BMI × 0.1). A threshold of 7.27 was identified as cutoff for the predictive risk of alcoholic cirrhosis development in 36 years from the onset of at-risk alcohol consumption with 70.1% sensitivity and 78.7% specificity.

Conclusion

We developed the first score for alcoholic cirrhosis prediction that combines clinical and genetic factors.

Associations between the tumor necrosis factor-α gene and interleukin-10 gene polymorphisms and risk of alcoholic liver disease: A meta-analysis

BACKGROUND

The critical roles of tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) in the pathogenesis of alcoholic liver diseases (ALD) suggest that functional variations in the TNF-α (TNFA) and IL-10 genes may be related to individual susceptibility to ALD. As available studies examining the associations between TNFA or IL-10 polymorphisms and ALD risk have yielded conflicting results, a meta-analysis was conducted to clarify the potential relation between TNFA and IL-10 polymorphisms and the risk of ALD.

METHODS

A comprehensive literature search was conducted to identify relevant studies. Pooled odds ratios and 95% confidence intervals were calculated using a random-effects model. The heterogeneity between studies was assessed using the Cochran's Q statistic and the I(2) statistic. Publication bias was assessed using funnel plots and the Egger's regression test.

RESULTS

A total of 17studies and 12studies were identified and included in the meta-analysis of the associations between TNFA polymorphisms and ALD risk, and IL-10 polymorphisms and ALD risk, respectively. The pooled results showed that the "A" allele of the TNFA-238G>A polymorphism was significantly associated with an increased risk of ALD. Significant differences in the allele and genotype distributions of the IL-10-1082A>G polymorphism were detected in the comparison between ALD patients and healthy controls, but not when comparing ALD patients and alcohol dependent individuals without ALD. No significant associations between other polymorphic loci and ALD risks were detected.

CONCLUSIONS

The TNFA-238G>A polymorphism was significantly associated with ALD risk, while the TNFA-308G>A polymorphism and IL-10 polymorphisms (-1082A>G and -592C>A) may not be associated with the individual susceptibility to ALD. The impact of combined TNFA and IL-10 polymorphisms on individual susceptibility to ALD needs to be investigated in future studies.

Proangiogenic factors in the development of HCC in alcoholic cirrhosis

Alcoholic liver disease, the most common cause of liver cirrhosis, is associated with an increased risk for hepatocellular carcinoma. Angiogenic factors have been implicated in pathophysiology of cirrhosis, and of hepatocellular carcinoma, and in particular of alcoholic liver cirrhosis, due to alcohol induced hypoxia associated with increased hepatic oxygen consumption. In one study, it was found that among genetic polymorphisms in proangiogenic factors, KDR and VEFGA may confer an increased risk of HCC, in patients with ALD. There is need of further studies of the proangiogenic factors in HCC, in order to help us define their use as prognostic markers and also as markers of response to treatment.

The MnSOD Ala16Val SNP: relevance to human diseases and interaction with environmental factors

The relevance of reactive oxygen species (ROS) production relies on the dual role shown by these molecules in aerobes. ROS are known to modulate several physiological phenomena, such as immune response and cell growth and differentiation; on the other hand, uncontrolled ROS production may cause important tissue and cell damage, such as deoxyribonucleic acid oxidation, lipid peroxidation, and protein carbonylation. The manganese superoxide dismutase (MnSOD) antioxidant enzyme affords the major defense against ROS within the mitochondria, which is considered the main ROS production locus in aerobes. Structural and/or functional single nucleotide polymorphisms (SNP) within the MnSOD encoding gene may be relevant for ROS detoxification. Specifically, the MnSOD Ala16Val SNP has been shown to alter the enzyme localization and mitochondrial transportation, affecting the redox status balance. Oxidative stress may contribute to the development of type 2 diabetes, cardiovascular diseases, various inflammatory conditions, or cancer. The Ala16Val MnSOD SNP has been associated with these and other chronic diseases; however, inconsistent findings between studies have made difficult drawing definitive conclusions. Environmental factors, such as dietary antioxidant intake and exercise have been shown to affect ROS metabolism through antioxidant enzyme regulation and may contribute to explain inconsistencies in the literature. Nevertheless, whether environmental factors may be associated to the Ala16Val genotypes in human diseases still needs to be clarified.

Polymorphisms of the CD14 genes are associated with susceptibility to alcoholic liver disease in Greek patients

BACKGROUND

The incidence and severity of alcoholic liver disease (ALD) in chronic drinkers has been found to correlate with some environmental factors and especially with the dose of alcohol consumption, but it is obvious that other parameters clearly contribute to individual alcohol susceptibility. Chronic ethanol exposure leads to continuous endotoxin-mediated Toll-like receptor-4 (TLR-4) and CD14 activation and subsequent cytokine release resulting in chronic inflammation with continued hepatocellular damage. Therefore, genetic studies of polymorphism in TLR-4 and CD14 genes seem to be appropriate in determining genetic susceptibility to ALD. Our aim is to evaluate in a series of Greek drinkers, the possible association of polymorphisms in the TLR-4 and CD14 genes with ALD.

METHODS

In 96 patients with ALD polymorphism of TLR-4 and CD14 genes were studied compared with 104 patients with cirrhosis of other etiology, 100 healthy subjects, and 50 patients with a history of alcohol abuse but without liver disease.

RESULTS

No association between ALD and the presence of the Asp299Gly and Thr399Ile polymorphisms in the TLR-4 gene could be documented in our patients. Regarding the CD14 -159 (C/T) genotypes, TT genotype and T allele were found to be overrepresented in alcoholic patients compared with patients with nonalcohol-induced liver disease and healthy controls. On the other side, when compared patients with ALD and patients with alcohol abuse and no liver disease, TT genotype was found to be significantly less frequent. There is no statistically significant association with the presence of the T allele and the severity of ALD, suggesting that CD14 polymorphism does not influence disease severity in advanced stages of the disease.

CONCLUSIONS

In our series in Greek patients with alcohol abuse and alcoholic cirrhosis, a significant negative association with the CD14 endotoxin receptor gene polymorphism (TT genotype) but not with the TLR-4 gene polymorphism was documented.

Relationships between single nucleotide polymorphisms of antioxidant enzymes and disease

The presence and progression of numerous diseases have been linked to deficiencies in antioxidant systems. The relationships between single nucleotide polymorphisms (SNPs) arising from specific antioxidant enzymes and diseases associated with elevated oxidative stress have been studied with the rationale that they may be useful in screening for diseases. The purpose of this narrative review is to analyse evidence from these studies. The antioxidant enzyme SNPs selected for analysis are based on those most frequently investigated in relation to diseases in humans: superoxide dismutase (SOD2) Ala16Val (80 studies), glutathione peroxidise (GPx1) Pro197Leu (24 studies) and catalase C-262T (22 studies). Although the majority of evidence supports associations between the SOD2 Ala16Val SNP and diseases such as breast, prostate and lung cancers, diabetes and cardiovascular disease, the presence of the SOD2 Ala16Val SNP confers only a small, clinically insignificant reduction (if any) in the risk of these diseases. Other diseases such as bladder cancer, liver disease, nervous system pathologies and asthma have not been consistently related to this SOD SNP genotype. The GPx1 Pro197Leu and catalase C-262T SNP genotypes have been associated with breast cancer, but only in a small number of studies. Thus, currently available evidence suggests antioxidant enzyme SNP genotypes are not useful for screening for diseases in humans.

Association of inflammation genes with alcohol dependence/abuse: a systematic review and a meta-analysis

The aim of the present work was to systematically review all association studies of inflammation genes with alcohol dependence/alcohol abuse (AD/AA) and to perform a meta-analysis. Odds ratios (ORs) were estimated by contrasting the ratio of counts of the 'high-risk' versus 'low-risk' alleles in AD/AA cases versus controls. Data reported in at least three published studies were available for four genetic polymorphisms [TNF-α-238 (rs361525, G/A); TNF-α-308 (rs1800629, G/A); IL-1RA (VNTR [86 bp]n); IL-10-592 (rs1800896, C/A)]. In total, nine meta-analyses were performed. Of these, only the TNF-α-238 polymorphism showed a significant association with AD/AA (OR=1.36, 95% CI: 1.05-1.76). This risk remained significant and increased slightly when we considered only patients with advanced alcohol-related liver disease (AALD) (OR=1.5, 95% CI: 1.13-1.98) but not when we considered only patients without AALD (OR=1.08, 95% CI: 0.5-2.35). Sensitivity analysis showed that this genetic association is derived from the AALD phenotype rather than from AD. Our approach is limited by our phenotype definition; some studies included chronic heavy drinkers (minimal daily consumption of 80 g for a minimal duration of 10 years) but without a standardized psychiatric assessment.

Polymorphisms in the interleukin-10 gene promoter and the risk of alcoholism and alcoholic liver disease in Caucasian Spaniard men

Controversy surrounds the possible influence of the single nucleotide polymorphisms (SNPs) of the interleukin-10 (IL-10) gene promoter on the risk for alcoholic liver disease. Our aim was to determine whether the SNP of the IL-10 gene promoter are associated with an increased risk for alcoholism and for alcoholic liver disease in male Spaniards. The -627 C>A SNP of the IL-10 gene promoter was assessed in a cohort of 344 Caucasian Spanish men, 168 alcoholics, and 176 nonalcoholics. The alcoholic group comprised 79 individuals without liver histopathologic abnormalities and 89 patients with chronic alcoholic liver disease. The nonalcoholic group was made of 62 healthy controls and 114 patients with chronic nonalcoholic liver disease. Genotyping was performed using PCR and automatic sequencing analysis methods on white cell DNA. Genotype and allele frequencies were compared by using the chi(2) test. Overall, no differences in either genotype and allele distribution was observed when comparing the four patient categories defined (P=0.62 and P=0.33, respectively). Subset analyses showed no differences in the genotype and allele distributions between all alcoholic and all nonalcoholic subjects (P=0.55 and P=0.29, respectively). This study failed to detect significant associations of the IL-10 -627C>A SNP and alcoholism or alcoholic liver disease in a cohort of Caucasian male Spaniards.

Tumor necrosis factor polymorphisms and alcoholic liver disease: a HuGE review and meta-analysis

The association between alcoholic liver disease (ALD) and tumor necrosis factor-alpha gene (TNFA) polymorphisms has been analyzed in several studies, but results have been conflicting. The main purpose of this study was to integrate previous findings and explore whether these polymorphisms are associated with susceptibility to ALD. The authors surveyed studies on the relation between TNFA gene polymorphisms and ALD by means of an electronic database search. A meta-analysis was conducted in a random-effects model. The association between ALD and the -238G>A or -308G>A polymorphism of the TNFA gene has been analyzed in 11 studies. Concerning the -238G>A polymorphism, the authors found a significant association between possession of the A allele and risk of alcoholic liver cirrhosis (odds ratio = 1.47, 95% confidence interval: 1.05, 2.07). Meta-analysis of the relation between the -308G>A polymorphism and ALD did not show any significant association. Given the limited number of studies and the potential biases, more data are needed to confirm the association described for the -238A allele.

Polymorphisms of microsomal triglyceride transfer protein gene and phosphatidylethanolamine N-methyltransferase gene in alcoholic and nonalcoholic fatty liver disease in Koreans

BACKGROUND

The pathogenesis of fatty liver is likely to depend on a complex interaction of environmental and genetic factors. We investigated a large-scale analysis of the association between microsomal triglyceride transfer protein (MTTP) and phosphatidylethanolamine N-methyltransferase (PEMT) polymorphism in alcoholic and nonalcoholic fatty liver disease.

METHODS

Five hundred and eighty-eight patients who visited the health promotion center were enrolled. To elucidate the possible role of genetic variation affecting triglyceride metabolism in fatty liver disease, the MTTP-I128T and PEMT-V175M polymorphisms were studied.

RESULTS

The I/I genotype and I allele frequency of MTTP polymorphism with alcoholic fatty liver was significantly higher than that of the normal control group (P=0.026 vs. 0.005). Genotype and allele frequency of PEMT, however, did not show a significant difference between control and fatty liver. I/I genotype of MTTP gene frequency in the drinkers with fatty livers was 85.4%, which was significantly higher than that in the drinkers without fatty liver, which was 68.4% (P=0.013). With regard to biochemical indicators, the alanine aminotransferase value of the I/I group was significantly higher than that of the I/T and T/T groups (P=0.04). Asparate aminotransferase, gamma-glutamyl transpeptidase, triglyceride, apolipoprotein B, and glucose concentration tended to be lower in the I/T and T/T groups than in the I/I group, but no statistically significant difference was found.

CONCLUSION

In this study, MTTP-I128T polymorphism is associated with central obesity, elevated liver enzymes, and alcoholic fatty liver disease.

Does the simultaneous tumor necrosis factor receptor 2, tumor necrosis factor promoter gene polymorphism represent a higher risk for alcoholic liver disease?

BACKGROUND AND AIM

Tumor necrosis factor alpha (TNF-alpha) is a proinflammatory cytokine that seems to play a crucial role in the pathogenesis of alcoholic liver disease (ALD). TNF-alpha exerts its effects by binding to specific receptors (TNFR); the polymorphism of TNFRII T587G has been associated with increased TNF apoptotic response and its presence may increase the risk to develop liver disease. The aim of this study was to evaluate the prevalence of the TNF-alpha G238A promoter and TNFRII polymorphisms, individually or simultaneously, in ALD.

METHODS

TNF-alpha G238A and TNFRII T587G polymorphisms were studied in 103 unrelated patients with ALD (biopsy confirmed or clinical evidence) and in 76 heavy drinkers without liver disease (NLD). Single nucleotide polymorphism gene was detected by a polymerase chain reaction-restriction fragment length polymorphisms method. All patients had, at least, a 5 year history of alcohol consumption greater than 80 g/day.

RESULTS

TNF-alpha G238A allele frequency was similar in both groups. TNFRII T587G allele frequency was slightly higher in the ALD group than in the NLD group (21 vs. 18%, P=NS). TNF-alpha G238A and TNFRII T587G were simultaneously present in six ALD patients and in none of NLD patients (P=0.04).

CONCLUSION

Although individually there was no association between TNFRII T587G or TNF-alpha G238A polymorphisms and ALD, this study suggests that the presence of both polymorphisms may enhance the susceptibility for ALD. TNF-alpha G238A may increase TNF-alpha production, which when associated with TNFRII T587G, can further exacerbate TNF-alpha response leading to a greater risk of ALD.

Serum TNF-alpha levels in relation to alcohol consumption and common TNF gene polymorphisms

Tumor necrosis factor-alpha (TNF-alpha) mediates alcohol-induced organ dysfunction, including alcoholic hepatitis. Variations in the TNF-alpha gene may underlie the individual predisposition to alcoholic liver disease. Measurement of serum TNF-alpha levels has become a routine in clinical practice. The study was aimed at investigating the level of serum TNF-alpha levels in adults and analyzing its relationship with different levels of alcohol consumption, as well as the potential interaction between alcohol consumption and common TNF-alpha gene polymorphisms in relation to TNF-alpha levels and liver disease. Serum TNF-alpha was measured in a random sample of 459 individuals from a general adult population and in 137 hospital-admitted alcoholics. Three common TNF-alpha gene polymorphisms (-238G> A, -308G> A, and -857C> T) were investigated in 419 of these individuals. In the general adult population, the TNF-alpha levels were similar in alcohol abstainers and alcohol drinkers. Alcoholics admitted to the hospital showed the highest TNF-alpha levels, which were correlated with liver dysfunction. We found no evidence of an interaction between alcohol consumption and TNF-alpha gene polymorphisms in relation to TNF-alpha levels. Carriers of the TNF -238A allele tended to have a higher prevalence of advanced liver disease than -238G homozygotes, confirming previous reports. In conclusion, light-to-moderate drinking had no significant effect on the levels of serum TNF-alpha levels. Serum TNF-alpha levels are elevated in alcoholics independently of common TNF gene polymorphisms.

A new genetic variant involved in genetic susceptibility to alcoholic liver cirrhosis: -330T>G polymorphism of the interleukin-2 gene

OBJECTIVE

Genetic factors may determine susceptibility to develop alcoholic liver cirrhosis, although it remains uncertain why only a minority of alcoholics suffers from this disease. A decrease in serum levels of interleukin-2 (IL-2) is usually found in alcoholic cirrhotics. In this study we examined the relationship between the -330T>G IL-2 gene (IL2) polymorphism and alcoholic liver cirrhosis.

METHODS

Genotyping of the aforementioned polymorphism was done by polymerase chain reaction and digestion with restriction enzymes in 257 male alcoholics (161 without liver disease and 96 with alcoholic liver cirrhosis) and 101 healthy controls. A logistic regression analysis was performed to adjust for potential confounders and to analyze the model of inheritance.

RESULTS

We found an association between the -330T>G IL2 polymorphism and alcoholic liver cirrhosis: the frequency of the allele T carriers (genotype TT and GT) was significantly higher in alcoholics with cirrhosis (96.9%) than in those without liver disease (89.4%, P=0.043).

CONCLUSION

We report for the first time that the possession of the -330T allele of the IL2 is associated with a higher risk of developing alcoholic liver cirrhosis and this fact may favor the progression of alcoholic liver disease.

Interleukin-10 gene polymorphism is associated with alcoholism but not with alcoholic liver disease

AIMS

To determine whether the functional polymorphism -592C>A of the interleukin (IL)-10 gene (IL10) influences the development of alcoholic liver disease or alcoholism in alcoholic Spanish subjects.

METHODS

The -592C>A IL10 polymorphism was analyzed by the polymerase chain reaction and digestion with restriction enzymes in 257 male alcoholics [161 without alcoholic liver disease and 96 with alcoholic liver cirrhosis (ALC)] and 100 male healthy controls.

RESULTS

We found no association between the -592C>A IL10 polymorphism and ALC. Meta-analysis combining this result and data from previous studies failed also to show any significant association between this polymorphism and alcoholic liver disease. However, the frequency of allele A carriers (CA and AA genotypes) was significantly higher in alcoholic patients (defined as patients with abuse or dependence of alcohol) than in healthy controls.

CONCLUSION

The -592C>A IL10 polymorphism is not related to the risk of ALC. Nevertheless, our study shows that alcoholism is associated with an excess of allele A carriers in alcoholic patients.

Mitochondrial dysfunction and oxidative stress in the pathogenesis of alcohol- and obesity-induced fatty liver diseases

Fatty liver disease associated with chronic alcohol consumption or obesity/type 2 diabetes has emerged as a serious public health problem. Steatosis, accumulation of triglyceride in hepatocytes, is now recognized as a critical "first-hit" in the pathogenesis of liver disease. It is proposed that steatosis "primes" the liver to progress to more severe liver pathologies when individuals are exposed to subsequent metabolic and/or environmental stressors or "second-hits." Genetic risk factors can also influence the susceptibility to and severity of fatty liver disease. Furthermore, oxidative stress, disrupted nitric oxide (NO) signaling, and mitochondrial dysfunction are proposed to be key molecular events that accelerate or worsen steatosis and initiate progression to steatohepatitis and fibrosis. This review article will discuss the following topics regarding the pathobiology and molecular mechanisms responsible for fatty liver disease: (1) the "two-hit" or "multi-hit" hypothesis, (2) the role of mitochondrial bioenergetic defects and oxidant stress, (3) the interplay between NO and mitochondria in fatty liver disease, (4) genetic risk factors and oxidative stress-responsive genes, and (5) the feasibility of antioxidants for treatment.

A study on the TNF-alpha system in Caucasian Spanish patients with alcoholic liver disease

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) is thought to be a critical driving force of inflammatory damage in alcoholic liver disease (ALD). We aimed to establish whether there is a correlation between plasma levels of the soluble TNF-alpha receptors 1 and 2 (sTNFR1 and sTNFR2) and the severity of liver damage in patients with ALD. We also aimed to elucidate whether functionally active polymorphisms in the promoter region of the TNF-alpha gene modulate the development of ALD.

DESIGN

We studied 614 Spaniards. Of these, 278 were alcoholics (103 without liver histologic abnormalities, 89 with non-cirrhotic liver disease and 86 with cirrhosis) and 336 were non-alcoholics (115 healthy controls, 114 with non-alcoholic non-cirrhotic liver disease and 107 with cirrhosis unrelated to alcohol). Plasma levels of sTNFR1 and sTNFR2 were determined by ELISA and results were expressed in ng/mL and subsequently converted in log(10). TNF-alpha gene promoter region polymorphisms at the positions -238, -308 and -863 were assessed by restriction fragment length polymorphisms (RFLPs) on white cell DNA. Differences in plasma sTNFR1 and sTNFR2 levels between groups were compared with the one-way and two-factor analysis of variance test, and Student's t-test. Genotype distribution and allele frequencies in the different groups were compared using the chi(2) test or Fisher's exact test.

RESULTS

sTNFR1 and sTNFR2 plasma levels were significantly higher in patients with cirrhosis than in those with non-cirrhotic liver disease (p<0.001) and individuals without liver disease (p<0.001), both in the alcoholic and the non-alcoholic group. Among cirrhotics, sTNFR1 and sTNFR2 levels had a significant positive correlation with the severity of the liver disease, graded with the Child-Pugh's score (p=0.003 and p<0.001, respectively). TNF-alpha genotype distribution and allele frequencies of the three loci assessed were similar in the groups studied, hence no particular genotype or haplotype could be linked to ALD.

CONCLUSIONS

The TNF-alpha system is activated in patients with cirrhosis of the liver irrespective of aetiology. TNF-alpha polymorphisms at positions -238, -308 and -863 are not linked to ALD.

Genetic background of the multifactorial liver and bile duct diseases

The majority of liver diseases, are complex. They are the results of interactions between several genes and environmental factors. Familial aggregation and higher concordance rate of monozygotic twins compared to those of dizygotic twins provide evidence for the importance of genetic factors in the pathogenesis. There are only limited data in connection with the genetic background of multifactorial liver diseases. In the future, the genetic background may permit prevention, early, accurate diagnosis, prediction of disease course, complications, prognosis, as well as treatment response.