Polymorphisms in the transforming growth factor-beta gene (TGF-beta) and the risk of advanced alcoholic liver disease

C allele in transforming growth factor-β1 rs1800471 gene polymorphisms might indicate a protective feature in encapsulating peritoneal sclerosis development

INTRODUCTION

Peritoneal fibrosis may progress in peritoneal dialysis (PD) patients to a fatal clinical condition called encapsulating peritoneal sclerosis (EPS). Transforming growth factor (TGF)-β plays a pivotal role in the pathogenesis of peritoneal fibrosis. We aimed to investigate the association among polymorphisms in the gene encoding TGF-β1, which were -509C/T (rs1800469), +869T/C (rs1982073), and +915G/C (rs1800471) in EPS patients.

METHODS

A total of 16 PD patients who were clinically and radiologically diagnosed with EPS were enrolled and 22 age- and gender-matched PD patients were selected as the non-EPS group.

RESULTS

G allele frequency at the rs1800471 gene polymorphism was significantly higher in the EPS group than non-EPS group (p = 0.005). Interestingly, the non-EPS group patients had CC or CG polymorphisms.

CONCLUSION

C allele in TGF-β1 rs1800471 gene polymorphisms might indicate a protective feature in EPS development. Knowing the presence of polymorphism may be effective in selecting renal replacement therapy in patients.

Genetic Variants of Alcohol Metabolizing Enzymes and Alcohol-Related Liver Cirrhosis Risk

Alcohol-related liver disease (ARLD) is a major public health issue caused by excessive alcohol consumption. ARLD encompasses a wide range of chronic liver lesions, alcohol-related liver cirrhosis being the most severe and harmful state. Variations in the genes encoding the enzymes, which play an active role in ethanol metabolism, might influence alcohol exposure and hence be considered as risk factors of developing cirrhosis. We conducted a case-control study in which 164 alcohol-related liver cirrhosis patients and 272 healthy controls were genotyped for the following functional single nucleotide variations (SNVs): ADH1B gene, rs1229984, rs1041969, rs6413413, and rs2066702; ADH1C gene, rs35385902, rs283413, rs34195308, rs1693482, and rs35719513; CYP2E1 gene, rs3813867. Furthermore, copy number variations (CNVs) for ADH1A, ADH1B, ADH1C, and CYP2E1 genes were analyzed. A significant protective association with the risk of developing alcohol-related liver cirrhosis was observed between the mutant alleles of SNVs ADH1B rs1229984 (P_c value = 0.037) and ADH1C rs283413 (P_c value = 0.037). We identified CNVs in all genes studied, ADH1A gene deletions being more common in alcohol-related liver cirrhosis patients than in control subjects, although the association lost statistical significance after multivariate analyses. Our findings support that susceptibility to alcohol-related liver cirrhosis is related to variations in alcohol metabolism genes.

Transforming growth factor-beta 1 polymorphisms and anti-tuberculosis drug-induced liver injury. Polymorphisms in TGFβ1 and its relationship with anti-tuberculosis drug-induced liver injury

AIM

There is evidence to suggest that transforming growth factor-beta 1 takes part in a series of physiological and pathological processes in the human body, including wound healing, tissue fibrosis and embryonic development. We hypothesized that polymorphisms in the transforming growth factor-beta 1 gene single nucleotide polymorphisms (SNPs) were associated with anti-tuberculosis drug-induced liver injury (ATLI).

METHODS

In a prospective study, 280 newly diagnosed tuberculosis patients were followed up for three months after initiating anti-tuberculosis therapy. Tag-SNPs of transforming growth factor-beta 1 were genotyped with the MassARRAY platform. The associations between SNPs and ATLI were analyzed by logistic regression analysis adjusting for confounding factors.

RESULTS

Of the 280 patients recruited in this study, 33 were excluded during the three months of follow-up, and 24 were diagnosed with ATLI and were considered as the ATLI group. The remaining 223 subjects without ATLI were considered as the non-ATLI group. After correction for potential confounding factors using a multivariate logistic regression analysis, we found that the frequencies of polymorphisms and haplotypes of transforming growth factor-beta 1 were similar in patients with ATLI and without ATLI.

CONCLUSION

The present results suggest that transforming growth factor-beta 1 polymorphisms do not play essential roles in the pathogenesis of ATLI in Chinese patients.

Polymorphisms in the TGF-β1 (rs1982037) and IL-2 (rs2069762, rs4833248) genes are not associated with inhibitor development in Iranian patients with hemophilia A

Objectives Development of neutralizing antibodies against factor VIII is the major complication in hemophilia care which makes replacement therapies ineffective. The reports showed that inflammatory cytokines play an important role in inhibitor production. In the present study, the relationship between inhibitor development and the polymorphisms of two cytokine genes was studied in severe hemophiliac patients from Iran. Methods In this case-control study, three polymorphisms of immune regulatory genes [TGF-β (rs1982037) and IL-2 (rs2069762, rs4833248)] were analyzed in 100 Iranian hemophilia A patients divided into 55 inhibitor positive and 45 inhibitor negative patients using Tetra primer ARMS PCR, and DNA sequencing. Results The analysis of polymorphisms in the TGF-β and IL-2 genes showed no association between the genotypes and the production of inhibitors (p > 0.05). Also, comparison of allele frequencies for TGF-β and IL-2 genes between two groups indicated no significant differences associated with the development of FVIII inhibitors (p > 0.05). Discussion In contrast with some reports involving the correlation between polymorphisms of the TGF-β1 and IL-2 genes and inhibitor development in the world, no statistically significant differences in analysis of the alleles and genotypes for TGF-β and IL-2 genes were found between the inhibitor and non-inhibitor Iranian patients. Thus, other genetic markers influencing the immune response to replacement therapy in patients with hemophilia should be identified. Conclusions Regarding our results in molecular predisposition for inhibitor development, further studies of effective genetic markers are required as a prerequisite for the development of novel immunogenic therapeutic approaches in the future.

No association between TGF-β1 polymorphisms and risk of nasopharyngeal carcinoma in a large North African case-control study

Background

Genetic susceptibility plays a key role in the development of nasopharyngeal carcinoma (NPC) and in fact the disease presents with an unusually high incidence in certain regions of the world like North Africa. We investigated the association between polymorphism of the Transforming growth factor-β1 (TGF-β1) and risk of NPC in North Africa. TGF-β1 is a multifunctional cytokine that acts as both a tumor suppressor and a stimulator of cancer development; it has been shown to influence risk of numerous other carcinomas including lung, breast and prostate cancer.

Methods

TGF-β1 polymorphisms C-509T and T869C were studied in a large North African sample of 384 NPC cases and 361 controls, matched for age, sex and urban or rural residence in childhood. Genotypes were determined using polymerase chain reaction–restriction fragment length polymorphism.

Results

No association was observed between individual single nucleotide polymorphisms or their haplotypes and NPC susceptibility (for TGF-β1 C-509T: OR = 0.74; 95 % CI 0.46 − 1.18; for TGF-β1 T869C: OR = 0.86; 95 % CI 0.56 − 1.31), even when the samples were stratified by age, gender and TNM stage.

Conclusion

Contrary to what has been observed in Asian samples, in our North African sample, the TGF-β1 C-509T and T869C polymorphisms did not substantially influence NPC susceptibility.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0337-8) contains supplementary material, which is available to authorized users.

Controlled clinical trial with pirfenidone in the treatment of breast capsular contracture: association of TGF-β polymorphisms

BACKGROUND

Breast capsular contracture (BCC) is a commonly adverse event postmammoplastly characterized by an immune response mediated by cytokines and transforming growth factor (TGF)-β1 resulting in excessive synthesis and deposit of extracellular matrix around the breast implant. Presence of TGF-β1 polymorphisms has been associated as a risk factor to develop fibroproliferative diseases.

METHODS

This open, controlled, prospective, and pilot clinical trial with 6 months duration was carried out to evaluate the efficacy of 1800 mg a day, of oral Pirfenidone (PFD) in the treatment of BCC (Baker Score III/IV) postmammoplasty. Twenty BCC cases received PFD and 14 BCC control cases underwent capsulectomy after 6 months of enrollment. Both groups were followed up for 6 more months up to 12 months to determine the relapse in the absence of PFD. Determination of TGF-β1 polymorphisms was performed to establish a correlation with capsular contracture.

RESULTS

PFD group experienced BCC-reduction in all breasts 6 months after enrollment. Only 1 of 20 cases relapsed after follow-up. In capsulectomy group, 2 of 14 cases presented progression to grade IV during presurgical period. All capsulectomy cases relapsed at end of follow-up. Nearly hundred percent of all patients studied in this protocol had a profibrogenic homozygous TGF-β1 polymorphism (codon 25; genotype Arg25Arg).

CONCLUSIONS

PFD is useful to improve BCC (Baker Score III/IV) postmammoplasty with no relapse after drug administration. There is also an association between capsular contracture and the presence of homozygous G/G TGF-β1 genotype.

Cellular mechanisms of tissue fibrosis. 1. Common and organ-specific mechanisms associated with tissue fibrosis

Fibrosis is a pathological scarring process that leads to destruction of organ architecture and impairment of organ function. Chronic loss of organ function in most organs, including bone marrow, heart, intestine, kidney, liver, lung, and skin, is associated with fibrosis, contributing to an estimated one third of natural deaths worldwide. Effective therapies to prevent or to even reverse existing fibrotic lesions are not yet available in any organ. There is hope that an understanding of common fibrosis pathways will lead to development of antifibrotic therapies that are effective in all of these tissues in the future. Here we review common and organ-specific pathways of tissue fibrosis.

Genetic variants of TNFα, IL10, IL1β, CTLA4 and TGFβ1 modulate the indices of alcohol-induced liver injury in East Indian population

Alcohol induced liver disease or alcoholic liver disease (ALD), a complex trait, encompasses a gamut of pathophysiological alterations in the liver due to continuous exposure to a toxic amount of alcohol (more than 80 g per day). Of all chronic heavy drinkers, only 15-20% develops hepatitis or cirrhosis concomitantly or in succession. Several studies revealed that inter-individual as well as inter-ethnic genetic variation is one of the major factors that predispose to ALD. The role of genetic factors in ALD has long been sought for in ethnically distinct population groups. ALD is fast emerging as an important cause of chronic liver disease in India; even in populations such as "Bengalis" who were "culturally immune" earlier. While the genetic involvement in the pathogenesis of ALD is being sought for in different races, the complex pathophysiology of ALD as well as the knowledge of population level diversity of the relevant alcohol metabolizing and inflammatory pathways mandates the need for well designed studies of genetic factors in ethnically distinct population groups. An array of cytokines plays a critical role as mediators of injury, inflammation, fibrosis and cirrhosis in ALD. We, therefore, studied the association of polymorphisms in five relevant cytokine genes with "clinically significant" ALD in an ethnic "Bengali" population in Eastern India. Compared with "alcoholic" controls without liver disease (n=110), TNFα -238AA genotype, IL1β -511CC genotype, TGFβ1 -509CC genotype and IL10 -592AA genotype were significantly overrepresented in ALD patients (n=181; OR=2.4 and 95% CI 1.2-5.5, P(genotype)=0.042, P(allelic)=0.008; OR=2.7 and 95% CI 1.2-5.9, P(genotype)=0.018, P(allelic)=0.023; OR=4.7 and 95% CI 1.7-13.1, P(genotype)=0.003, P(allelic)=0.014; and OR=2.2 and 95% CI 1.1-4.8, P(genotype)=0.04, P(allelic)=0.039 respectively). Moreover a cumulative genetic risk analysis revealed a significant trend for developing ALD with an increase in the number of risk alleles on IL10 and TGFβ1 loci among alcoholics. The risk genotype of IL1β and TGFβ1 also influences the total bilirubin, albumin and alanine aminotransferase levels among alcoholic "Bengalis". The present study is the first case-control study from Eastern India that comprehensively identified polymorphic markers in TNFα, IL10, IL1β and TGFβ1 genes to be associated with ALD in the Bengali population, accentuating the significance of genetic factors in clinical expressions of ALD.

Genetic polymorphism at codon 10 of the transforming growth factor-β1 gene in patients with alcoholic liver cirrhosis

Background/Aims

Transforming growth factor beta1 (TGF-β1) is a key cytokine in the production of extracellular matrix. A genetic polymorphism at codon 10 of the TGF-β1 gene is associated with liver fibrosis. We investigated the effect of genetic polymorphisms at codon 10 on the development of alcoholic liver cirrhosis (ALC).

Methods

In total, 119 controls and 182 patients with ALC, were enrolled in the study. Clinical and laboratory data including total lifetime alcohol intake were collected at enrollment. The genotype at codon 10 was determined for each patient by single-strand conformation polymorphism.

Results

There were three types of genetic polymorphism at codon 10: homozygous proline (P/P), heterozygous proline/leucine (P/L), and homozygous leucine (L/L). Among the controls, the proportions of P/P, P/L, and L/L were 26.1%, 44.5%, and 29.4%, respectively in the ALC group, these proportions were 23.1%, 43.4%, and 33.5%, respectively. The genotype distribution did not differ between the controls and the ALC group. In the ALC group, age, total lifetime alcohol intake, and distribution of Child-Pugh class did not differ with the genotype. Of the male patients with ALC (n=164), the proportions of P/P, P/L, and L/L were 20.1%, 44.5%, and 35.4%, respectively the genotype distribution did not differ between the male controls and the male ALC patients.

Conclusions

The genotype at codon 10 in TGF-β1 does not appear to influence the development of ALC. Further study is needed to investigate other genetic factors that influence the development of ALC in patients with chronic alcohol intake.

Association with TGF-β1 gene polymorphisms and reproductive performance of Large white pig

As a multifunctional cytokine, transforming growth factor-beta1 (TGF-β1) was detected in the utero-placental interface during early pregnancy in the pig and believed to enhance trophoblast attachment to the endometrium. In this experiment, we selected TGF-β1 as the candidate gene affecting litter size in pigs. Four polymorphic loci of TGF-β1 gene were found by PCR-SSCP (single-strand conformation polymorphism) in Large white sows (n = 567): C→T mutation at 33nt in the intron 4; G→A mutation at 179nt in the intron 6; C→T mutation at 1043nt in the intron 6; GG→AA linkage mutations at 2490nt and 2494nt respectively. We haplotyped these SNPs as: CGCAA (denote as P) and TATGG (denote as K). The effects of three haplotypic combinations (HCs) of PP, PK and KK on litter sizes were investigated by a linear model. It was found that for the first parity litters, the least squares mean for total number born (TNB) of KK was 1.02 piglets/litter, higher than that of PK (p < 0.05), 0.49 piglets/litter higher than that of PP (p > 0.1). There were no significant differences between HCs on the second parity. The result indicated that KK HCs was significantly associated with pig litter size.

Two common nonsynonymous paraoxonase 1 (PON1) gene polymorphisms and brain astrocytoma and meningioma

BACKGROUND

Human serum paraoxonase 1 (PON1) plays a major role in the metabolism of several organophosphorus compounds. The enzyme is encoded by the polymorphic gene PON1, located on chromosome 7q21.3. Aiming to identify genetic variations related to the risk of developing brain tumors, we investigated the putative association between common nonsynonymous PON1 polymorphisms and the risk of developing astrocytoma and meningioma.

METHODS

Seventy one consecutive patients with brain tumors (43 with astrocytoma grade II/III and 28 with meningioma) with ages ranging 21 to 76 years, and 220 healthy controls subjects were analyzed for the frequency of the nonsynonymous PON1 genotypes L55M rs854560 and Q192R rs662. All participants were adult Caucasian individuals recruited in the central area of Spain.

RESULTS

The frequencies of the PON1 genotypes and allelic variants of the polymorphisms PON1 L55M and PON1 Q192R did not differ significantly between patients with astrocytoma and meningioma and controls. The minor allele frequencies were as follows: PON1 55L, 0.398, 0.328 and 0.286 for patients with astrocytoma, meningioma and control individuals, respectively; PON1 192R, 0.341, 0.362 and 0.302 for patients with astrocytoma, meningioma and control individuals, respectively. Correction for age, gender, or education, made no difference in odds ratios and the p values remained non-significant. Haplotype association analyses did not identify any significant association with the risk of developing astrocytoma or meningioma.

CONCLUSIONS

Common nonsynonymous PON1 polymorphisms are not related with the risk of developing astrocytoma and meningioma.

Alcoholic liver disease and hepatitis C: A frequently underestimated combination

Alcoholic liver disease (ALD) and hepatitis C virus (HCV) infection represent, either alone or in combination, more than two thirds of all patients with liver disease in the Western world. This review discusses the epidemiology and combined impact of ALD and HCV on the progression of liver disease. ALD and HCV affect the progression of liver disease to liver cirrhosis and hepatocellular carcinoma (HCC) in a synergistic manner. Thus, the risk for HCC increases five times with a daily alcohol consumption of 80 g; in the presence of HCV it is increased 20-fold, and a combination of both risk factors leads to a more than 100-fold risk for HCC development. Alcohol consumption also decreases the response to interferon treatment which is probably due to a lack of compliance than a direct effect on HCV replication. Several molecular mechanisms are discussed that could explain the synergistic interaction of alcohol and HCV on disease progression. They include modulation of the immune response and apoptosis, increased oxidative stress via induction of CYP2E1 and the hepatic accumulation of iron. Thus, both HCV and alcohol independently cause hepatic iron accumulation in > 50% of patients probably due to suppression of the liver-secreted systemic iron hormone hepcidin. A better understanding of hepcidin regulation could help in developing novel therapeutic approaches to treat the chronic disease in the future. For now, it can be generally concluded that HCV-infected patients should abstain from alcohol and alcoholics should be encouraged to participate in detoxification programs.

Current experimental perspectives on the clinical progression of alcoholic liver disease

Chronic alcohol abuse is an important cause of morbidity and mortality throughout the world. Liver damage due to chronic alcohol intoxication initially leads to accumulation of lipids within the liver and with ongoing exposure this condition of steatosis may first progress to an inflammatory stage which leads the way for fibrogenesis and finally cirrhosis of the liver. While the earlier stages of the disease are considered reversible, cirrhotic destruction of the liver architecture beyond certain limits causes irreversible damage of the organ and often represents the basis for cancer development. This review will summarize current knowledge about the molecular mechanisms underlying the different stages of alcoholic liver disease (ALD). Recent observations have led to the identification of new molecular mechanisms and mediators of ALD. For example, plasminogen activator inhibitor 1 was shown to play a central role for steatosis, the anti-inflammatory adipokine, adiponectin profoundly regulates liver macrophage function and excessive hepatic deposition of iron is caused by chronic ethanol intoxication and increases the risk of hepatocellular carcinoma development.

Genetic variation in transforming growth factor-beta1 gene associated with increased risk of esophageal squamous cell carcinoma

The genetic alterations leading to esophageal squamous cell carcinoma (ESCC) are gradually being discovered. A wide variety of genes have been associated with ESCC development as well as tumor progression. Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine; it promotes tumor growth and metastasis in later stages of of cancer development. Variations in the DNA sequence in the TGF-beta1 gene may lead to altered TGF-beta1 production and/or activity, and so this can modulate an individual's susceptibility to ESCC. To test this hypothesis, we investigated the association of the TGF-beta1 gene -509 C/T and 869 T/C (Leu10Pro) polymorphisms and their haplotypes with the risk of ESCC. 247 patients with ESCC and 260 age- and sex-matched controls were studied using a polymerase chain reaction-restriction fragment length polymorphism. There were significant differences in the genotype and allele distribution of 869 T/C polymorphism of the TGF-beta1 gene among cases and controls. The 869 TC and CC genotypes were associated with a significantly increased risk of ESCC as compared with the 869 TT genotypes [odds ratio (OR) = 1.882, 95% confidence interval (CI) 1.212-2.923, P = 0.005 and OR = 2.099, 95% CI 1.288-3.421, P = 0.003, respectively]. Consistent with the results of the genotyping analyses, the -509 T/869 C haplotype was associated with a significantly increased risk of ESCC as compared with the -509 C/869 T haplotype (OR = 1.463; 95% CI 1.120-1.912; P = 0.005). This study shows for the first time that TGF-beta1 gene 869 T/C polymorphism may contribute to a genetic risk factor for ESCC in a Chinese population.

Evaluation of the transforming growth factor beta1 codon 25 (Arg-->Pro) polymorphism in alcoholic liver disease

INTRODUCTION

Liver cirrhosis develops only in a minority of heavy drinkers. Genetic factors may account for some variation in the progression of fibrosis in alcoholic liver disease (ALD). Transforming growth factor beta 1 (TGFbeta1) is a key profibrogenic cytokine in fibrosis and its gene contains several polymorphic sites. A single nucleotide polymorphism at codon 25 has been suggested to affect fibrosis progression in patients with chronic hepatitis C virus infection, fatty liver disease, and hereditary hemochromatosis. Its contribution to the progression of ALD has not been investigated sufficiently so far.

PATIENTS AND METHODS

One-hundred-and-fifty-one heavy drinkers without apparent ALD, 149 individuals with alcoholic cirrhosis, and 220 alcoholic cirrhotics who underwent liver transplantation (LTX) were genotyped for TGFbeta1 codon 25 variants.

RESULTS

Univariate analysis suggested that genotypes Arg/Pro or Pro/Pro are associated with decompensated liver cirrhosis requiring LTX. However, after adjusting for patients' age these genotypes did not confer a significant risk for cirrhosis requiring LTX.

CONCLUSION

TGFbeta1 codon 25 genotypes Arg/Pro or Pro/Pro are not associated with alcoholic liver cirrhosis. Our study emphasizes the need for adequate statistical methods and accurate study design when evaluating the contribution of genetic variants to the course of chronic liver diseases.

Association of transforming growth factor-β1 gene polymorphisms with genetic susceptibility to nasopharyngeal carcinoma

BACKGROUND

Nasopharyngeal cancer (NPC) is multifactorial, and the genetic background may be a crucial etiologic factor. Transforming growth factor-beta1 (TGF-beta1) is a multifunctional cytokine, it promotes tumor growth and metastasis in later stages of phase of cancer development. Variations in the DNA sequence in the TGF-beta1 gene may lead to altered TGF-beta1 production and/or activity, and so this can modulate an individual's susceptibility to NPC. To test this hypothesis, we investigated the association of the TGF-beta1 polymorphisms and their haplotypes with the risk of NPC in a Chinese population.

METHODS

We analyzed 2 single nucleotide polymorphisms (SNPs) of TGF-beta1 gene promoter -509C/T and 869T/C (Leu10Pro) at exon one in 108 patients with NPC and 120 age- and sex-matched controls in a Chinese population, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) strategy.

RESULTS

There were significant differences in the genotype and allele distribution of -509C/T and 869T/C (Leu10Pro) polymorphisms of the TGF-beta1 gene among cases and controls. The -509T and 869C alleles carriers were associated with a significantly increased risk of NPC as compared with the non-carriers (OR=1.64, 95% CI, 1.13-2.39, P=0.009 and OR=1.70, 95% CI, 1.17-2.46, P=0.006, respectively). Consistent with the results of the genotyping analyses, the -509T/869C haplotype was associated with a significantly increased risk of NPC as compared with the -509C/869T haplotype (OR=1.68; 95% CI, 1.14-2.48; P=0.009).

CONCLUSION

TGF-beta1 -509C/T and 869T/C polymorphisms, and their haplotypes are significantly associated with the risk of NPC. Our data suggests that TGF-beta1 -509C/T and 869T/C polymorphisms could be used as genetic susceptibility markers of the NPC.

Noninvasive assessment of fibrosis in non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)

The term "non-alcoholic fatty liver disease" (NAFLD) encompasses a wide range of pathological conditions ranging from accumulation of fat (fatty liver) to various degrees of inflammation and fibrosis (NASH), and finally to cryptogenic cirrhosis and its clinical sequelae (HCC, liver decompensation). The progression from one stage to the next can be triggered by genetic and environmental factors alone and also through their interaction. Fatty liver is known to follow a benign course, whereas the presence of inflammation, ballooning degeneration, and fibrosis, which are typical features of NASH, can lead to cirrhosis. Despite the serious risks associated with NASH, there are few tools for monitoring the progression of the disease and identification of high-risk patients. The aim of this article is to review the pros and cons of some noninvasive methods for assessing liver fibrosis in NASH.

Alcohol and the liver

PURPOSE OF REVIEW

To apprise the reader of advances in 2005 in the epidemiology, pathogenesis, prognosis and treatment of alcoholic liver disease. Alcohol use has declined in developed countries, but the opposite is true elsewhere; alcoholic liver disease is a considerable burden worldwide.

RECENT FINDINGS

Genetic mechanisms for alcoholic liver disease are being discovered in addition to aggravating cofactors, such as hepatitis C, obesity and iron overload, and ameliorating ones, like coffee and tea drinking. The involvement of the innate immune system and the mechanisms of apoptosis in alcoholic liver disease are better appreciated, especially the emerging role of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). Steroid use and nutrition for alcoholic hepatitis are being refined, and the validity of the model for end-stage liver disease (MELD) score in predicting the outcome of alcoholic liver disease is upheld. Recidivism after liver transplantation for alcoholic liver disease adversely impacts long-term survival.

SUMMARY

Inroads are being made into the genetics of alcoholic liver disease and new phenomena are being uncovered in its pathogenesis, but safe and effective therapies for both alcoholic hepatitis and alcoholic cirrhosis are still wanting.

The role of genetic polymorphisms in alcoholic liver disease

Chronic alcohol consumption is a major cause of liver cirrhosis which, however, develops in only a minority of heavy drinkers. Evidence from twin studies indicates that genetic factors account for at least 50% of individual susceptibility. The contribution of genetic factors to the development of diseases may be investigated either by means of animal experiments, through linkage studies in families of affected patients, or population based case-control studies. With regard to the latter, single nucleotide polymorphisms of genes involved in the degradation of alcohol, antioxidant defense, necroinflammation, and formation and degradation of extracellular matrix are attractive candidates for studying genotype-phenotype associations. However, many associations in early studies were found to be spurious and could not be confirmed in stringently designed investigations. Therefore, future genotype-phenotype studies in alcoholic liver disease should meet certain requirements in order to avoid pure chance observations due to a lack of power, false functional interpretation, and insufficient statistical evaluation.