Genetics of non-alcoholic fatty liver disease: From susceptibility and nutrient interactions to management

Genomic Exploration of Nonalcoholic Fatty Liver Disease: Insights From Gene Expression and Variation in Morbidly Obese Individuals

Nonalcoholic fatty liver disease (NAFLD) is a common liver condition resulting from metabolic syndrome characterized by fat accumulation in the liver. It is often associated with obesity and diabetes, contributing to hepatic steatosis in liver cells. The prevalence of NAFLD is increasing globally, with 32% of the adult population affected. Genetic modifiers, such as single nucleotide polymorphisms, can increase susceptibility to the disease. Gene expression analysis and genetic variation can help identify disease-causing pathways and reveal biomarkers involved in NAFLD. This study employed integrative bioinformatics analysis, including bulk RNA-seq and single-cell RNA-seq, to explore differentially expressed genes and their genetic variants in NAFLD vs. control and NAFLD vs. cirrhosis, highlighting genes influencing NAFLD progression. Moreover, this study identified AKR1D1, LIPC, UGT2B17, DGAT2, and SERPINE1 implicated in metabolic, immune, and lipid functions while being overexpressed in both hepatocyte cells among obese patients identified and validated through Liver Cell Atlas, highlighting their pivotal role in the pathogenesis of the disease in obese patients through perturbed hepatocytes. Furthermore, novel pathogenic variants of AKR1D1, LIPC, and SERPINE1, associated with congenital bile acid synthesis defects, abnormal circulating lipid concentrations, and plasminogen activator inhibitor type 1 deficiency conditions, were identified. Conclusively, this integrative multiomics study highlights the novel pathogenic variants of AKR1D1, LIPC, and SERPINE1 in metabolic, immune, and lipid pathways that are highly expressed among hepatocytes in obese patients while possibly carrying pathogenic mutations that may be associated with NAFLD, emphasizing their potential as novel targets for therapeutic strategies and biomarker development in early diagnosis and treatment before the onset of cirrhosis or hepatocellular carcinoma.

Disparities in Metabolic Dysfunction-Associated Steatotic Liver Disease Prevalence, Diagnosis, Treatment, and Outcomes: A Narrative Review

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly known as non-alcoholic fatty liver disease (NAFLD), is a leading cause of morbidity and mortality, and health disparities have been shown to influence disease burden.

AIM

In this review, we aim to characterize disparities in prevalence, diagnosis, treatment, and outcomes of MASLD, and to make recommendations for next steps to minimize these disparities.

METHODS

Literature search on PubMed and Scopus databases was conducted to identify relevant articles published before September 2, 2024.

RESULTS

Relative to women and White populations, MASLD is more common in men and Hispanic populations and less common in Black populations. It is also more prevalent among those with lower SES. Noninvasive clinical scores may perform differently across groups, and screening practices vary both for initial disease and for progression to metabolic dysfunctionassociated steatohepatitis (MASH), formerly called non-alcoholic steatohepatitis (NASH). Women and Black and Hispanic patients suffer worse outcomes including rates of progression to MASH and mortality.

CONCLUSIONS

Health disparities related to race, ethnicity, gender, and socioeconomic factors impact multiple stages of care for patients with MASLD.

Dietary composition and its association with metabolic dysfunction-associated fatty liver disease among Chinese adults: A cross-sectional study

BACKGROUND AND STUDY AIMS

Metabolic dysfunction-associated fatty liver disease (MAFLD) has become the most common cause of chronic liver disease worldwide. Diet plays a critical role in the prevention and treatment of MAFLD. Our hypothesis was that the intake of some macronutrients, vitamins, or mineral elements is associated with MAFLD.

PATIENTS AND METHODS

Patients with MAFLD can be diagnosed based on the evidence of hepatic steatosis and if they meet any of the three additional criteria of overweight/obesity, diabetes mellitus, or metabolic dysregulation. Diets were recorded using photographs and diaries of meals for seven consecutive days. The consumed dietary composition was compared with the recommended intake according to the China Food Composition Tables (Standard Edition) version 2019 and the Chinese Dietary Reference Intakes version 2013, and its association with MAFLD was assessed by logistical regression analyses.

RESULTS

A total of 229 MAFLD patients and 148 healthy controls were included in this study. MAFLD patients, compared with that by non-MAFLD participants, consumed more polyunsaturated fatty acids (PUFAs) (p < 0.001), vitamin E (p < 0.001), and iron (p = 0.008). The intake of PUFAs (OR = 1.070, 95 % CI: 1.017-1.127, p = 0.009) and vitamin E (OR = 1.100, 95 % CI: 1.018-1.190, p = 0.016) was positively associated with MAFLD. In addition, the percentages of individuals who consumed PUFAs (p = 0.006), vitamin E (p < 0.001), or iron (p = 0.046) above the recommended intake were higher among the individuals with MAFLD. Daily intake of PUFAs > 11 % (OR = 2.328, 95 % CI: 1.290-4.201, p = 0.005) and vitamin E > 14 mg (OR = 2.189, 95 % CI: 1.153-4.158, p = 0.017) was positively correlated with MAFLD.

CONCLUSIONS

Patients with MAFLD consumed more PUFAs, vitamin E, and iron in their daily diet. Excessive consumption of PUFAs and vitamin E might be independent risk factors for the incidence of MAFLD.

Hepatocytic Ballooning in Non-alcoholic Steatohepatitis: Bridging the Knowledge Gap and Charting Future Avenues

Non-alcoholic steatohepatitis (NASH) is emerging as a significant global health concern, characterized by hepatic lipid accumulation, inflammation, and hepatocellular injury. Hepatocytic ballooning, a histological feature of NASH, has gained prominence for its role in disease progression and potential as a therapeutic target. This review provides an overview of the current knowledge regarding hepatocytic ballooning in NASH, highlighting the key molecular and cellular mechanisms implicated in its development. We delve into the intricate interplay of metabolic dysregulation, oxidative stress, and lipid toxicity as drivers of hepatocytic ballooning, shedding light on the pathways responsible for its initiation and perpetuation. Furthermore, we explore the diagnostic challenges associated with hepatocytic ballooning and its significance as a prognostic indicator in NASH patients. While hepatocytic ballooning holds promise as a therapeutic target, this abstract discusses the various experimental and clinical approaches to ameliorate this histological hallmark. Potential interventions, including lifestyle modifications, pharmacological agents, and emerging therapies, are evaluated in terms of their efficacy and safety profiles. In conclusion, this review underscores the need to bridge the knowledge gap surrounding hepatocytic ballooning in NASH and emphasizes its importance in understanding disease pathogenesis and progression. By charting future research avenues and clinical strategies, we aspire to advance our comprehension of NASH and ultimately improve patient outcomes in this rapidly evolving field of hepatology.

PNPLA3 148M/M Is More Susceptible to Palmitic Acid-Induced Endoplasmic Reticulum Stress-Associated Apoptosis in HepG2 Cells

BACKGROUND

Patatin-like phospholipase domain-containing 3 (PNPLA3) is a major susceptibility gene for nonalcoholic fatty liver disease (NAFLD), and its rs738409 (I148M) polymorphism is associated with the occurrence and progression of NAFLD. Endoplasmic reticulum (ER) stress-related hepatocyte lipoapoptosis contributes to the progress of NAFLD. PNPLA3 is also known as a member of the calcium-independent phospholipase A2ε family, which can hydrolyze fatty acids to generate lysophosphatidylcholine (LPC) that induces ER stress-related hepatocyte lipoapoptosis. Whether the PNPLA3 risk genotype 148M/M is involved in more severe ER stress-associated lipoapoptosis is unclear.

METHODS

A PNPLA3148I knock-in HepG2 cell model was constructed based on HepG2 expressing PNPLA3 148M/M using the Cas9/sgRNA system. PNPLA3 148M/M, I/M, and I/I cells were treated with 0.3 mM palmitic acid (PA) for 24 h to induce lipid deposition. Cellular lipid deposition was detected by oil red staining. Apoptosis was observed by TUNEL. LPC was determined by ELISA, and the expression of PNPLA3, the ER stress marker Bip, molecules involved in the ER stress PERK/elF-2a pathway, and its downstream C/EBP homologous protein (CHOP)-mediated apoptotic pathway were detected by western blot.

RESULTS

The results showed no difference in PNPLA3 basal expression and basal hepatocyte lipid content between the three genotypes of cells. Lipid deposition and apoptosis were more severe in PNPLA3 148M/M and 148I/M cells than in I/I cells after PA treatment. PA-induced upregulation of protein expression of Bip, ER stress-responsive PERK pathway molecules p-PERK, p-eIF2α, CHOP, and CHOP-associated apoptotic molecules PUMA and Bax were more pronounced in PNPLA3 148M/M cells than in PNPLA3 148I/I cells. The basal LPC levels and the PA-treated increase of LPC levels in the cell culture supernatants did not differ between the three genotypic cells.

CONCLUSION

PNPLA3 148M/M cells were more susceptible to PA-induced lipid deposition and ER stress-related apoptosis than 148I/I cells, and the proapoptotic susceptibility of PNPLA3 148M/M is independent of LPC.

Association of xenobiotic-metabolizing enzymes (GSTM1 and GSTT 1), and pro-inflammatory cytokines (TNF-α and IL-6) genetic polymorphisms with non-alcoholic fatty liver disease

Previous studies have revealed that genetic polymorphisms of the Glutathione S-transferase M1 and T1 (GSTM1 and GSTT1), tumor necrosis factor-α (TNF-α), and interleukin 6 (IL-6) are associated with the presence of non-alcoholic fatty liver disease (NAFLD) in many populations. This study was conducted to investigate the association of the GSTM1, GSTT1, TNF-α rs1800629, and IL-6 rs1800795 with NAFLD in the general Iranian population. A case-control analysis included 242 NAFLD patients and 324 healthy controls from Iranian adults. After the physical examination, the genotypes were determined by polymerase chain reaction(PCR). The GSTM1 null, GSTT1 null, TNF-α AG/AA, and IL-6 CG/CC genotypes were deemed to be high-risk. The null allele of GSTM1 and A allele of TNF-α were more frequent in NAFLD patients even after Bonferroni's correction (P values<0.005, adjusted odds ratio (OR), 1.66 and 2.02; 95% confidence intervals (CI), (1.18-2.32) and (1.34-3.34), respectively. The IL-6 CC/CG genotype association with NAFLD was not significant after correction (P value = 0.04) Polymorphisms of xenobiotic and pro-inflammatory genes are associated with NAFLD in the Iranian population and seem to be a useful tool for NAFLD prevention and care.

Could phthalates exposure contribute to the development of metabolic syndrome and liver disease in humans?

In the study, 305 patients of both genders were enrolled and divided into three groups: obese (BMI > 30 kg/m²), patients who were diagnosed type 2 diabetes mellitus (T2DM), and control, normal weight healthy volunteers. At least one of ten different phthalate metabolites was determined in the urine samples of 49.84% all enrolled participants. In the obese subgroup, the sum of all urinary phthalate metabolites was positively associated with TG levels (p = 0.031) together with derived TC/HDL and TG/HDL ratios (p = 0.023 and 0.015), respectively. Urinary MEP concentration was positively correlated with the HOMA-IR in T2DM subgroup (p = 0.016) while in the control subgroup, log₁₀MEP levels were negatively correlated with total cholesterol (p = 0.0051), and LDL serum levels (p = 0.0015), respectively. Also, in the control subgroup, positive linear correlations between urinary log₁₀MEP levels and TyG and TYG-BMI values (p = 0.028 and p = 0.027), respectively, were determined. Urinary MEHP levels were associated with glucose serum levels (p = 0.02) in T2DM subgroup, while in the control HDL values were negatively associated with log₁₀MEHP (p = 0.0035). Healthy volunteers exposed to phthalates had elevated AST levels in comparison to non-exposed ones (p = 0.023). In control subgroup, ALT and AST values were increased (p = 0.02 and p = 0.01, respectively) in MEP exposed while GGT levels were enhanced (p = 0.017) in MEHP exposed in comparison with non-exposed. Combined phthalates influence on glucose and lipid metabolism may increase the possibility for NAFLD and insulin resistance development among exposed individuals.

Relationship between N,N-dimethylformamide exposure, PNPLA3, GCKR, COL13A1 and TM6SF2 genes, and liver injury

BACKGROUND

Current researches show that N,N-dimethylformamide (DMF) exposure is associated with liver injury, but it is debatable whether PNPLA3, GCKR, COL13A1 and TM6SF2 gene polymorphisms are associated with liver injury. Our objective was to examine the relationship among DMF exposure, PNPLA3 rs738409, GCKR rs780094, COL13A1 rs1227756, TM6SF2 rs58542926 and liver injury.

METHODS

The cohort consisted of 461 workers exposed above the DMF threshold limit value (TLV) and 211 exposed below the DMF TLV in China, who were followed for 5 years. The relationship between the measured dose of DMF and the relative risk (RR) of liver injury was also investigated by Poisson analysis. Logistic regression models were used to examine the association between measured dose of DMF, gene locus, and RR for liver injury. All workers had a annual physical examinations were conducted at certified physical examination centers in Taicang CDC, including liver serum transaminase assessment and abdominal ultrasound. Genomic DNA was extracted from peripheral blood leukocytes using a genomic DNA extraction kit.

RESULTS

The incidence of liver injury in the above DMF TLV group was significantly higher than in the below DMF TLV group. GCKR rs780094 was associated with liver injury. The interaction among the GCKR rs780094, DMF exposure and liver injury showed no significant association.

CONCLUSIONS

Our data indicated that in DMF exposure, GCKR rs780094 may contribute to the risk of liver injury. Our results suggest that GCKR rs780094 is a useful genetic marker to help identify liver injury.

An exploratory phenome wide association study linking asthma and liver disease genetic variants to electronic health records from the Estonian Biobank

The Estonian Biobank, governed by the Institute of Genomics at the University of Tartu (Biobank), has stored genetic material/DNA and continuously collected data since 2002 on a total of 52,274 individuals representing ~5% of the Estonian adult population and is increasing. To explore the utility of data available in the Biobank, we conducted a phenome-wide association study (PheWAS) in two areas of interest to healthcare researchers; asthma and liver disease. We used 11 asthma and 13 liver disease-associated single nucleotide polymorphisms (SNPs), identified from published genome-wide association studies, to test our ability to detect established associations. We confirmed 2 asthma and 5 liver disease associated variants at nominal significance and directionally consistent with published results. We found 2 associations that were opposite to what was published before (rs4374383:AA increases risk of NASH/NAFLD, rs11597086 increases ALT level). Three SNP-diagnosis pairs passed the phenome-wide significance threshold: rs9273349 and E06 (thyroiditis, p = 5.50x10-8); rs9273349 and E10 (type-1 diabetes, p = 2.60x10-7); and rs2281135 and K76 (non-alcoholic liver diseases, including NAFLD, p = 4.10x10-7). We have validated our approach and confirmed the quality of the data for these conditions. Importantly, we demonstrate that the extensive amount of genetic and medical information from the Estonian Biobank can be successfully utilized for scientific research.

Comparison of variation in frequency for SNPs associated with asthma or liver disease between Estonia, HapMap populations and the 1000 genome project populations

Allele-specific analyses to understand frequency differences across populations, particularly populations not well studied, are important to help identify variants that may have a functional effect on disease mechanisms and phenotypic predisposition, facilitating new Genome-Wide Association Studies (GWAS). We aimed to compare the allele frequency of 11 asthma-associated and 16 liver disease-associated single nucleotide polymorphisms (SNPs) between the Estonian, HapMap and 1000 genome project populations. When comparing EGCUT with HapMap populations, the largest difference in allele frequencies was observed with the Maasai population in Kinyawa, Kenya, with 12 SNP variants reporting statistical significance. Similarly, when comparing EGCUT with 1000 genomes project populations, the largest difference in allele frequencies was observed with pooled African populations with 22 SNP variants reporting statistical significance. For 11 asthma-associated and 16 liver disease-associated SNPs, Estonians are genetically similar to other European populations but significantly different from African populations. Understanding differences in genetic architecture between ethnic populations is important to facilitate new GWAS targeted at underserved ethnic groups to enable novel genetic findings to aid the development of new therapies to reduce morbidity and mortality.

Genetic and Epigenetic Profile of Patients With Alcoholic Liver Disease

Alcoholic liver disease (ALD) is a definition encompassing a spectrum of disorders ranging from simple steatosis to cirrhosis and hepatocellular carcinoma. Excessive alcohol consumption triggers a series of metabolic reactions that affect the liver by inducing lipogenesis, increasing oxidative stress, and causing abnormal inflammatory responses. The metabolic pathways regulating lipids, reactive oxygen species (ROS), and immune system are closely related and in some cases cross-regulate each other. Therefore, it must be taken into account that major genetic and epigenetic abnormalities affecting enzymes involved in one of such pathways can play a pivotal role in ALD pathogenesis. However, recent studies have pointed out how a significant predisposition can also be determined by minor variants, such as relatively common polymorphisms, epigenetic modifications, and microRNA abnormalities. Genetic and epigenetic factors can also affect the progression of liver diseases, promoting fibrogenesis, cirrhosis, and ultimately hepatocellular carcinoma. It is noteworthy that some of these factors, such as some of the cytokines involved in the abnormal inflammatory responses, are shared with non-alcoholic liver disease, while other factors are unique to ALD. The study of the genetic and epigenetic components involved in the liver damages caused by alcohol is crucial to identify individuals with high risk of developing ALD, design personalized protocols for prevention and/or treatment, and select the best molecular targets for new therapies.

Metabolic and genetic markers' associations with elevated levels of alanine aminotransferase in adolescents

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), the most common chronic liver disease in adolescents, is a feature of metabolic syndrome (MetS). Obesity and insulin resistance (IR) are risk factors for NAFLD, as well as inflammation-related genetic markers. The relationship between metabolic or inflammation-related genetic markers and alanine aminotransferase (ALT) is not fully understood. We examined the relationship of MetS, metabolic and inflammation-related genetic markers with elevated ALT in adolescents.

METHODS

A total of 674 adolescents participated in a cross-sectional study in Guadalajara, Mexico. Elevated ALT (>40 IU/L), a surrogate marker of NAFLD, and MetS (International Diabetes Federation definition) were evaluated. Obesity, IR, lipids, C-reactive protein (CRP) and genetic markers (TNFA-308G>A, CRP+1444C>T, IL1RN and IL6-597/-572/-174 haplotype) were evaluated. Multivariate logistic regression was performed.

RESULTS

Elevated ALT was observed in 3% and 14.1% (total and obese, respectively) of the adolescents. Obesity (odds ratio [OR], 5.86; 95% confidence interval [95% CI], 1.16-25.89), insulin (OR, 8.51; 95% CI, 2.61-27.71), IR (OR, 9.10; 95% CI, 2.82-29.38), total cholesterol (TC) (OR, 3.67; 95% CI, 1.25-10.72), low-density lipoprotein-cholesterol (LDL-C) (OR, 3.06; 95% CI, 1.06-8.33), non-high-density lipoprotein-cholesterol (HDL-C) (OR, 3.88; 95% CI, 1.27-11.90) and IL1RN (OR, 4.64; 95% CI, 1.10-19.53) were associated with elevated ALT. Among males, ≥2 MetS criteria were associated with elevated ALT (OR, 4.22; 95% CI, 1.14-15.71).

CONCLUSIONS

Obesity, insulin, IR, high TC, high LDL-C, high non-HDL-C and IL1RN polymorphism were associated with elevated ALT. Among males, ≥2 MetS criteria were associated with elevated ALT. There is an urgent need to reduce obesity and IR in adolescents to prevent NAFLD.

Bisphenol a increases risk for presumed non-alcoholic fatty liver disease in Hispanic adolescents in NHANES 2003-2010

BACKGROUND

Bisphenol-A (BPA) is a ubiquitous chemical and recognized endocrine disruptor associated with obesity and related disorders. We explored the association between BPA levels and suspected non-alcoholic fatty liver disease (NAFLD).

METHODS

Unweighted analyses were used to study the relationship between urinary BPA levels and suspected NAFLD (alanine aminotransferase (ALT). > 30 U/L, body mass index (BMI) Z-score > 1.064 and evidence of insulin resistance) using National Health and Nutrition Examination Survey (NHANES) data (2003-2010) on 12-19 year olds. Unweighted and weighted analyses were used to evaluate the risk with only elevated ALT.

RESULTS

We included 944 adolescents with urinary BPA and fasting laboratory tests from a total of 7168 adolescents. Risk of suspected NAFLD was increased in the second quartile of BPA levels (1.4-2.7 ng/mL) when compared to the first (< 1.4 ng/mL) (Odds Ratio (OR) 4.23, 95% Confidence Interval (CI) 1.44-12.41). The ORs for the third and second quartiles were positive but did not reach statistical significance. The association was stronger in Hispanics (n = 344) with BPA levels in the second (OR 6.12, 95% C.I. 1.62-23.15) quartile and when limiting the analyses to overweight/obese adolescents (n = 332), in the second (OR 5.56, 95% C.I. 1.28-24.06) and fourth BPA quartiles (OR 6.85, 95% C.I. 1.02-46.22) compared to the first quartile. BPA levels were not associated with ALT elevation.

CONCLUSIONS

The risk of suspected NAFLD is increased in participants in higher quartiles of BPA exposure, particularly in those of Hispanic ethnicity. Further studies are required to fully understand the potential role of BPA in non-alcoholic fatty liver disease.

Hydroxysteroid (17β) dehydrogenase 13 deficiency triggers hepatic steatosis and inflammation in mice

Hydroxysteroid (17β) dehydrogenases (HSD17Bs) form an enzyme family characterized by their ability to catalyze reactions in steroid and lipid metabolism. In the present study, we characterized the phenotype of HSD17B13-knockout (HSD17B13KO) mice deficient in Hsd17b13. In these studies, hepatic steatosis was detected in HSD17B13KO male mice, indicated by histologic analysis and by the increased triglyceride concentration in the liver, whereas reproductive performance and serum steroid concentrations were normal in HSD17B13KO mice. In line with these changes, the expression of key proteins in fatty acid synthesis, such as FAS, acetyl-CoA carboxylase 1, and SCD1, was increased in the HSD17B13KO liver. Furthermore, the knockout liver showed an increase in 2 acylcarnitines, suggesting impaired mitochondrial β-oxidation in the presence of unaltered malonyl CoA and AMPK expression. The glucose tolerance did not differ between wild-type and HSD17B13KO mice in the presence of lower levels of glucose 6-phosphatase in HSD17B13KO liver compared with wild-type liver. Furthermore, microgranulomas and increased portal inflammation together with up-regulation of immune response genes were observed in HSD17B13KO mice. Our data indicate that disruption of Hsd17b13 impairs hepatic-lipid metabolism in mice, resulting in liver steatosis and inflammation, but the enzyme does not play a major role in the regulation of reproductive functions.-Adam, M., Heikelä, H., Sobolewski, C., Portius, D., Mäki-Jouppila, J., Mehmood, A., Adhikari, P., Esposito, I., Elo, L. L., Zhang, F.-P., Ruohonen, S. T., Strauss, L., Foti, M., Poutanen, M. Hydroxysteroid (17β) dehydrogenase 13 deficiency triggers hepatic steatosis and inflammation in mice.

Mediterranean Diet and Multi-Ingredient-Based Interventions for the Management of Non-Alcoholic Fatty Liver Disease

Non-alcoholic fatty liver disease (NAFLD) comprises a wide spectrum of hepatic disorders, from simple steatosis to hepatic necro-inflammation leading to non-alcoholic steatohepatitis (NASH). Although the prevalence of these multifactorial pathologies is continuously increasing in the population, there is still not an established methodology for their treatment other than weight loss and a change in lifestyle habits, such as a hypocaloric diet and physical exercise. In this framework, there is increasing evidence that several food bioactives and dietary patterns are effective for reversing and preventing the onset of these pathologies. Some studies have claimed that better responses are obtained when treatments are performed under a multifaceted approach, using different bioactive compounds that act against complementary targets. Thus, in this work, current strategies for treating NAFLD and NASH based on multi-ingredient-based supplements or the Mediterranean diet, a dietary pattern rich in bioactive compounds, are reviewed. Furthermore, the usefulness of omics techniques to design effective multi-ingredient nutritional interventions and to predict and monitor their response against these disorders is also discussed.

Regional differences in genetic susceptibility to non-alcoholic liver disease in two distinct Indian ethnicities

AIM

To validate the association of variants in PNPLA3 (rs2281135) and TM6SF2 (rs58542926) genes with ultrasound detected non-alcoholic fatty liver disease (NAFLD).

METHODS

A total of 503 individuals with and without fatty infiltration were recruited. Fatty infiltration was confirmed based on ultrasound findings. Anthropometric data and blood samples were collected from the study group. DNA was isolated from peripheral blood, quality and quantity was assessed by gel electrophoresis and spectrophotometer respectively. Genotyping of the variants in PNPLA3 and TM6SF2 genes was carried out by employing taqman probes (C_15875080_10 for PNPLA3 and C_8946351_10 for TM6SF2 SNP) on real time PCR (Stepone-Lifetechnologies). Genotype data was tested for deviations from Hardy-Weinberg equilibrium. χ2 test was used to analyze the statistical significance of the difference in genotype distribution of the studied variants in patients and controls and the strength of association was expressed as odds ratio (95%CI). A two-tailed P value of ≤ 0.05 was considered statistically significant.

RESULTS

The study group comprised of 503 individuals of which 256 had fatty infiltration and 247 without fatty infiltration and thus formed the patient and control groups respectively. As the patient group could be divided in to two distinct ethnicities (ancestral South Indians-ASI and North-East Indians-NEI), further recruitment of control cohort and association analyses was carried out based on ethnicities. Of the 256 with fatty infiltration 93 were ASI and 163 were NEI and of the 247 controls 138 were ASI and 109 were NEI. As expected, there were significant differences in the anthropometric and other clinical data between the control and the patient groups. However significant differences within the ethnicities were also noted. While rs2281135 in PNPLA3 gene was significantly associated (P = 0.03) with higher risk (odds 1.9, 95%CI: 1.5-3.14, P = 0.03) of NAFLD in NEI ethnicity, rs58542926 in TM6SF2 gene was significantly associated with NAFLD with a 2.7 fold higher risk (odds 2.7, 95%CI: 1.37-5.3, P = 0.0004) of the disease. There were significantly higher proportions of individuals with variants in both the genes in the patient group in both ASI (patients - 14/93 and controls - 7/138; P = 0.009) and NEI ethnicities (patients - 17/163 and controls - 7/109; P = 0.01).

CONCLUSION

Although the study identified distinct genetic susceptibility in the two ethnicities, transheterozygosity of the variants suggests higher risk of NAFLD in individuals with both the variants.

Omega-3 polyunsaturated fatty acids as a treatment strategy for nonalcoholic fatty liver disease

Obese and type 2 diabetic (T2DM) patients have a high prevalence of nonalcoholic fatty liver disease (NAFLD). NAFLD is a continuum of chronic liver diseases ranging from benign hepatosteatosis to nonalcoholic steatohepatitis (NASH), cirrhosis and primary hepatocellular cancer (HCC). Because of its strong association with the obesity epidemic, NAFLD is rapidly becoming a major public health concern worldwide. Surprisingly, there are no FDA approved NAFLD therapies; and current therapies focus on the co-morbidities associated with NAFLD, namely, obesity, hyperglycemia, dyslipidemia, and hypertension. The goal of this review is to provide background on the disease process, discuss human studies and preclinical models that have examined treatment options. We also provide an in-depth rationale for the use of dietary ω3 polyunsaturated fatty acid (ω3 PUFA) supplements as a treatment option for NAFLD. This focus is based on recent studies indicating that NASH patients and preclinical mouse models of NASH have low levels of hepatic C_20-22 ω3 PUFA. This decline in hepatic PUFA may account for the major phenotypic features associated with NASH, including steatosis, inflammation and fibrosis. Finally, our discussion will address the strengths and limitations of ω3 PUFA supplements use in NAFLD therapy.

Non-alcoholic fatty liver disease: An expanded review

Non-alcoholic fatty liver disease (NAFLD) encompasses the simple steatosis to more progressive steatosis with associated hepatitis, fibrosis, cirrhosis, and in some cases hepatocellular carcinoma. NAFLD is a growing epidemic, not only in the United States, but worldwide in part due to obesity and insulin resistance leading to liver accumulation of triglycerides and free fatty acids. Numerous risk factors for the development of NAFLD have been espoused with most having some form of metabolic derangement or insulin resistance at the core of its pathophysiology. NAFLD patients are at increased risk of liver-related as well as cardiovascular mortality, and NAFLD is rapidly becoming the leading indication for liver transplantation. Liver biopsy remains the gold standard for definitive diagnosis, but the development of noninvasive advanced imaging, biochemical and genetic tests will no doubt provide future clinicians with a great deal of information and opportunity for enhanced understanding of the pathogenesis and targeted treatment. As it currently stands several medications/supplements are being used in the treatment of NAFLD; however, none seem to be the "magic bullet" in curtailing this growing problem yet. In this review we summarized the current knowledge of NAFLD epidemiology, risk factors, diagnosis, pathogenesis, pathologic changes, natural history, and treatment in order to aid in further understanding this disease and better managing NAFLD patients.