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Association between the HFE C282Y, H63D Polymorphisms and the Risks of Non-Alcoholic Fatty Liver Disease, Liver Cirrhosis and Hepatocellular Carcinoma: An Updated Systematic Review and Meta-Analysis of 5,758 Cases and 14,741 Controls

  • Qing Ye ,

    Contributed equally to this work with: Qing Ye, Bao-Xin Qian

    Affiliations The Third Central clinical college of Tianjin Medical University, Tianjin, PR China, Department of Gastroenterology and Hepatology, Tianjin Third Central Hospital, Tianjin, PR China, Tianjin Institute of Hepatobiliary Disease, Tianjin, PR China, Tianjin Key Laboratory of Artificial Cells, Tianjin, PR China

  • Bao-Xin Qian ,

    Contributed equally to this work with: Qing Ye, Bao-Xin Qian

    Affiliations The Third Central clinical college of Tianjin Medical University, Tianjin, PR China, Department of Gastroenterology and Hepatology, Tianjin Third Central Hospital, Tianjin, PR China, Tianjin Institute of Hepatobiliary Disease, Tianjin, PR China, Tianjin Key Laboratory of Artificial Cells, Tianjin, PR China

  • Wei-Li Yin,

    Affiliations The Third Central clinical college of Tianjin Medical University, Tianjin, PR China, Department of Gastroenterology and Hepatology, Tianjin Third Central Hospital, Tianjin, PR China, Tianjin Institute of Hepatobiliary Disease, Tianjin, PR China, Tianjin Key Laboratory of Artificial Cells, Tianjin, PR China

  • Feng-Mei Wang,

    Affiliations The Third Central clinical college of Tianjin Medical University, Tianjin, PR China, Department of Gastroenterology and Hepatology, Tianjin Third Central Hospital, Tianjin, PR China, Tianjin Institute of Hepatobiliary Disease, Tianjin, PR China, Tianjin Key Laboratory of Artificial Cells, Tianjin, PR China

  • Tao Han

    hantaomd@126.com

    Affiliations The Third Central clinical college of Tianjin Medical University, Tianjin, PR China, Department of Gastroenterology and Hepatology, Tianjin Third Central Hospital, Tianjin, PR China, Tianjin Institute of Hepatobiliary Disease, Tianjin, PR China, Tianjin Key Laboratory of Artificial Cells, Tianjin, PR China

Association between the HFE C282Y, H63D Polymorphisms and the Risks of Non-Alcoholic Fatty Liver Disease, Liver Cirrhosis and Hepatocellular Carcinoma: An Updated Systematic Review and Meta-Analysis of 5,758 Cases and 14,741 Controls

  • Qing Ye, 
  • Bao-Xin Qian, 
  • Wei-Li Yin, 
  • Feng-Mei Wang, 
  • Tao Han
PLOS
x

Abstract

Background

Conflicting results have been obtained for the association between two common polymorphisms (C282Y, H63D) of human HFE (hereditary hemochromatosis) gene and the risks of the liver diseases, including non-alcoholic fatty liver disease (NAFLD), liver cirrhosis and hepatocellular carcinoma (HCC).

Methods

An updated systematic review and meta-analysis was conducted to evaluate the potential role of HFE polymorphisms in the susceptibility to NAFLD, liver cirrhosis and HCC. After retrieving articles from online databases, eligible studies were enrolled according to the selection criteria. Stata/SE 12.0 software was utilized to perform the statistical analysis.

Results

In total, 43 articles with 5,758 cases and 14,741 controls were selected. Compared with the control group, a significantly increased risk of NAFLD was observed for the C282Y polymorphism in the Caucasian population under all genetic models and for the H63D polymorphism under the allele, heterozygote and dominant models (all OR>1, Passociation<0.05). However, no significant difference between liver cirrhosis cases and the control group was observed for HFE C282Y and H63D (all Passociation>0.05). In addition, we found that HFE C282Y was statistically associated with increased HCC susceptibility in the overall population, while H63D increased the odds of developing non-cirrhotic HCC in the African population (all OR>1, Passociation<0.05). Moreover, a positive association between compound heterozygosity for C282Y/H63D and the risk of NAFLD and HCC, but not liver cirrhosis, was observed.

Conclusion

Our meta-analysis provides evidence that the HFE C282Y and H63D polymorphisms confer increased genetic susceptibility to NAFLD and HCC but not liver cirrhosis. Additional well-powered studies are required to confirm our conclusion.

Introduction

Hepatocellular carcinoma (HCC) often occurs as the end-stage or more aggressive form of many progressive chronic liver diseases, such as NAFLD (non-alcoholic fatty liver disease), liver cirrhosis, and chronic viral hepatitis [14]. NAFLD is a series of chronic liver disease with fat deposition in the absence of significant alcohol consumption, including simple fatty liver, NASH (non-alcoholic steatohepatitis), liver fibrosis and cirrhosis [5, 6]. Liver cirrhosis is a common clinical chronic liver injury that is characterized by the formation of microscopic or macroscopic nodules separated by bands of fibrous tissue, impairment of hepatocellular function, and obstruction of portal circulation [3, 4]. There are many types of liver cirrhosis, such as cryptogenic cirrhosis, alcoholic liver cirrhosis, viral liver cirrhosis and NAFLD-associated cirrhosis, which are considered as the key risk factors for the occurrence of HCC [38]. Various polymorphisms of genes, such as patatin-like phospholipase domain containing 3 (PNPLA3), transmembrane 6 superfamily member (TM6SF2) 2 and methylenetetrahydrofolate reductase (MTHFR), are involved in susceptibility to the above liver diseases [916].

Human hereditary hemochromatosis (HFE) gene, first identified by Feder JN et al. in 1996, is located on the short arm of chromosome 6 (6p21.3) [17]. The HFE gene encodes a 343-amino acid glycoprotein (HFE protein), a member of the major histocompatibility complex class I-like family [17, 18]. As a key component of iron homeostasis in humans, the HFE protein is linked to the incidence of hereditary hemochromatosis (HH), an autosomal recessive disorder [17, 18]. Several common polymorphisms of the HFE gene, such as C282Y (rs1800562), H63D (rs1799945) and S65C (rs1800730), have been reported [18, 19]. Accumulating evidence indicates that HFE mutations are associated with susceptibility to many clinical diseases, such as Parkinson's disease (PD) [20], primary varicose veins [21] and coronary heart disease (CHD) [22].

Although several previous meta-analyses on the association of HFE genetic variants and NAFLD and HCC risk have been reported [12, 13, 2326], a meta-analysis of the association of HFE gene mutation and overall liver cirrhosis has not been published, and more comprehensive systematic review and updated meta-analysis is therefore necessary to determine the relationship between HFE polymorphism and susceptibility to NAFLD, liver cirrhosis and HCC. Due to the limited data on S65C, we assessed the genetic risk conferred by the two common polymorphisms of HFE (C282Y and H63D). Our findings demonstrated that there is an association between HFE C282Y polymorphism and increased risk of NAFLD in the Caucasian population and HCC but not liver cirrhosis. Additionally, H63D polymorphism is likely to increase susceptibility to HCC without cirrhosis.

Methods

The current meta-analysis followed the guidelines [27] of “Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)” and “Meta-analysis on Genetic Association Studies” (shown in S1 and S2 Tables) with small modifications.

Systematic literature search

Five electronic databases (published prior to August 1st, 2016), including PubMed, EMBASE, Web of Science (WOS), Scopus and China National Knowledge Infrastructure (CNKI), were thoroughly searched for potential records. S3 Table presents the full details of the literature search based on the combination of index terms, such as “HFE”, “NAFLD”, “liver cirrhosis”, “HCC” and “single nucleotide polymorphism”. There were no restrictions of language, publication type or geographic location.

Selection criteria and data extraction

Potential records from the systematic literature search were selected for eligible studies. We utilized EndNote X7 software to remove duplicate records and screened the title and abstract to exclude unrelated records based on the following criteria: (1) Review or book; (2) Not clinical data; (3) Other gene; (4) Other disease; (5) Case, trial, or non-polymorphism; (6) Meta-analysis; and (7) Meeting abstract. After the assessment of eligibility, all eligible articles were required to provide sufficient data regarding the genotype distribution of HFE polymorphism in both the case and control groups. The following basic information was extracted independently by the authors (QY BXQ WLY FMW): name of the first author, year of publication, country, ethnicity, sample sizes, source of control, genotyping methods for SNP, disease definition, diagnostic method, genotype frequencies, and the P value of the Hardy-Weinberg-Equilibrium (HWE) test in the control group. For unavailable or missing data, we attempted to contact the corresponding or first author through E-mail or the ResearchGate website.

Quality assessment

Three authors (QY BXQ WLY) independently assessed the methodological quality of the included studies, according to the Newcastle-Ottawa Scale (NOS) system, which is available from http://www.ohri.ca/programs/clinicalepidemiology/oxford.html [28]. The NOS quality score system was used to critically evaluate the quality of non-randomized studies in the meta-analysis based on the following items: “case/control definition”, “representativeness of the cases”, “selection of controls”, “comparability of cases and controls” and “ascertainment of exposure”. An NOS score ≥ 7 was considered as a high-quality study. A thorough discussion with other authors was required to settle conflicting evaluations and discrepancies.

Statistical analysis

The values of pooled odds ratios (ORs), 95% confidence intervals (CIs) and Passociation were determined through Mantel-Haenszel statistics using Stata/SE 12.0 (Stata Corporation, TX, USA) software. A Passociation<0.05 indicated a significant difference between the case and control groups. Five inheritance models, namely, allele (Y vs C for C282Y, D vs H for H63D), homozygote (YY vs CC, DD vs HH), heterozygote (CY vs CC, HD vs HH), dominant (CY+YY vs CC, HD+DD vs HH) and recessive models (YY vs CC+CY, DD vs HH+HD), were applied.

Cochran’s Q statistic and I2 test were performed to evaluate the potential heterogeneities among studies. A random-effect model was used when the existence of significant heterogeneity was not excluded (PHeterogeneity value of Q statistic<0.1 or I2 value>25%). To investigate the potential sources of heterogeneity, subgroup analyses based on ethnicity, source of controls, genotyping methods, HWE and disease type (such as NASH, alcoholic cirrhosis, cryptogenic cirrhosis) were conducted. In addition, both Begg’s test and Egger’s test were performed to assess the potential publication bias, and sensitivity analysis was conducted to evaluate whether the results were statistically stable. The PHWE value was obtained from a chi-squared test, and PHWE greater than 0.05 was considered as being in agreement with HWE.

Results

Characteristics of the eligible studies

There were 43 eligible articles with 5,758 cases and 14,741 controls included in our meta-analysis [7, 8, 10, 19, 2967], including 16 articles on NAFLD [19, 2943], 18 articles on liver cirrhosis [7, 8, 31, 4458] and 17 articles on HCC [7, 10, 44, 46, 48, 51, 52, 5867]. These articles met our inclusion/exclusion criteria. Thirty-nine studies of high quality (NOS score ≥6) [7, 8, 10, 2936, 3854, 56, 5867] and 4 studies of moderate quality (NOS score = 6) [19, 37, 55, 57] were identified. S4 Table presents the summarized characteristics and methodological quality of selected studies, and S5 and S6 Tables show the genotype distributions of the HFE C282Y and H63D polymorphisms in NAFLD, liver cirrhosis and HCC disease.

A total of 1,287 potential records were obtained from the PubMed (n = 391), EMBASE (n = 219), WOS (n = 583), Scopus (n = 90) and CNKI (n = 4) databases, and 469 duplicate records were removed by EndNote software. Additionally, 699 records were excluded by screening the title and abstract for the following: Review or book (n = 317), Not clinical data (n = 34), Other gene (n = 48), Other disease (n = 166); Case, trial, or non-polymorphism (n = 114); and Meta-analysis (n = 20). The authors (QY BXQ WLY FMW) independently extracted the data from 119 full-text articles and removed 76 articles, including 24 articles, which were meeting abstracts, and 52 articles, which lacked usable data. A flow diagram of the literature search strategy for the meta-analysis is presented in Fig 1.

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Fig 1. Flow diagram of the search strategy for the meta-analysis.

https://doi.org/10.1371/journal.pone.0163423.g001

C282Y and H63D polymorphism and NAFLD risks

We first investigated the genetic association between the HFE C282Y polymorphism and the susceptibility to NAFLD. A random-effect model was used for Mantel-Haenszel statistics due to the high degree of heterogeneity (Fig 2A and Table 1, all I2 >25%, Pheterogeneity<0.1). The pooled results in Fig 2A and Table 1 show that compared with the control group, increased NAFLD risk was observed in the case group under the allele (OR = 1.95, Passociation = 0.012), heterozygote (OR = 1.87, Passociation = 0.016) and dominant models (OR = 1.95, Passociation = 0.014) but not in the other models.

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Fig 2. Meta-analysis of the genetic relationship between the C282Y and H63D polymorphisms of HFE and NAFLD risk under the allele model.

(A) Forest plot for C282Y under the Y vs C model; (B) Forest plot for H63D under the D vs H model; (C) Begg’s test for C282Y; (D) Begg’s test for H63D.

https://doi.org/10.1371/journal.pone.0163423.g002

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Table 1. Pooled analysis for the association between HFE C282Y, H63D genotype frequencies and the risks of NAFLD, liver cirrhosis, HCC.

https://doi.org/10.1371/journal.pone.0163423.t001

Moreover, subgroup analyses under all genetic models were conducted based on ethnicity (Asian, Caucasian and Mixed), source of controls (PB and HB), genotyping methods (PCR-RFLP and other), HWE (PHWE>0.05 and PHWE <0.05) and specific disease type (NASH). As shown in S7 Table, a significantly increased NAFLD risk was observed in the Caucasian population, with PHWE >0.05 subgroup (all OR>1, Passociation<0.05). These data suggested that HFE C282Y may be linked to the risk of NAFLD, especially in the Caucasian population.

An association between HFE H63D and NAFLD risk was also detected. No large heterogeneity was detected (Fig 2B and Table 1, all I2<25%, Pheterogeneity>0.1). As shown in Fig 2B and Table 1, increased NAFLD risk was observed in the models of D vs H (OR = 1.21, Passociation = 0.003), HD vs HH (OR = 1.22, Passociation = 0.010), and HD+DD vs HH (OR = 1.24, Passociation = 0.004). A similar significant difference was observed in the subgroup analysis for the Asian population, PB, PCR-RFLP, and NASH (S8 Table, Passociation<0.05, OR>1). Therefore, the HD genotype of HFE H63D contributes to increased NAFLD susceptibility.

C282Y and H63D polymorphism and liver cirrhosis risk

The data in Fig 3A and Table 1 show that a fixed-effect model was used for the meta-analysis of the association between HFE C282Y and liver cirrhosis risk (all I2<25%, Pheterogeneity>0.1). No significant difference between the control and case group was observed for C282Y under all genetic models (Fig 3A, Table 1 and S7 Table, all Passociation>0.05). For H63D, as shown in Fig 3B and Table 1, a fixed-effect model was used for the homozygote and recessive contrasts (all I2 = 0.0%, Pheterogeneity>0.1), whereas a random-effect model was used for the others (all I2>25.0%, Pheterogeneity<0.1). There were no significant differences under the majority of comparisons in the meta-analysis and subsequent subgroup analysis (Table 1 and S8 Table, Passociation>0.05), except for the allele, homozygote and recessive models in the Asian population and the allele model in the PHWE>0.05 group. These data failed to provide strong evidence of a significant correlation between HFE C282Y and H63D and liver cirrhosis risk.

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Fig 3. Meta-analysis of the genetic relationship between the C282Y and H63D polymorphisms of HFE and liver cirrhosis risk under the allele model.

(A) Forest plot for C282Y under the Y vs C model; (B) Forest plot for H63D under the D vs H model; (C) Begg’s test for C282Y; (D) Begg’s test for H63D.

https://doi.org/10.1371/journal.pone.0163423.g003

C282Y and H63D polymorphism and HCC risk

A random-effect model was used to analyze the genetic association between HFE C282Y and HCC risk (Fig 4A and Table 1, all I2>25%, Pheterogeneity<0.1), and an increased HCC risk was observed under all genetic models in the overall population (all OR>1, Passociation<0.05). A similar significant difference was observed in the pooled analysis in the PB, PHWE>0.05 and cirrhosis (-) subgroups under the allele, homozygote, dominant and recessive models (S7 Table, OR>1, Passociation<0.05). For H63D polymorphism, no increased HCC risk was observed in the overall population (Fig 4B and Table 1, all Passociation>0.05); however, there was a significant difference in the African population and the cirrhosis (-) subgroup (S8 Table, all OR>1, Passociation<0.05). Our data demonstrated that HFE C282Y may increase the odds of developing HCC, while HFE H63D is more likely associated with susceptibility to HCC without cirrhosis in the African population.

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Fig 4. Meta-analysis of the genetic relationship between the C282Y and H63D polymorphisms of HFE and HCC risk under the allele model.

(A) Forest plot for C282Y under the Y vs C model; (B) Forest plot for H63D under the D vs H model; (C) Begg’s test for C282Y; (D) Begg’s test for H63D.

https://doi.org/10.1371/journal.pone.0163423.g004

Compound heterozygosity for C282Y/H63D and the risks of NAFLD, liver cirrhosis, and HCC

Next, to study the potential role of compound heterozygosity for C282Y/H63D in susceptibility to NAFLD, liver cirrhosis and HCC, we performed a meta-analysis and subgroup analysis. As shown in S1AS3A Figs and S9 Table, a random-effect model was used for NAFLD, whereas fixed-effect models were used for liver cirrhosis and HCC. A significant difference was observed for NAFLD in the Caucasian population (OR = 2.13, Passociation = 0.023) and for HCC in the overall population (OR = 1.70, Passociation = 0.039) but not for liver cirrhosis (all Passociation>0.05). These data suggested that the effect of C282Y+H63D compound heterozygosity may contribute to an increased risk of NAFLD and HCC.

Publication bias and sensitivity analysis

To evaluate the potential publication bias among the included studies, Begg’s test and Egger’s test were performed. For C282Y polymorphism, large publication bias was excluded under all genetic models for NAFLD, liver cirrhosis and HCC (Table 1 and Figs 2C, 3C and 4C, all PBegg>0.05, PEegger>0.05). For H63D polymorphism, small publication bias was observed in the DD vs HH (Table 1, PBegg = 0.015 for liver cirrhosis, PBegg = 0.041 for HCC) and DD vs HH+HD models (Table 1, PBegg = 0.013 for liver cirrhosis, PBegg = 0.019 for HCC). However, there was no evidence of publication bias in the other models (Table 1 and Figs 2D, 3D and 4D, all PBegg>0.05, PEegger>0.05). No obvious publication bias was observed for compound heterozygosity for C282Y/H63D (S1B, S1C, S3B and S3C Figs and S9 Table, all PBegg>0.05, PEegger>0.05). Moreover, the sensitivity analysis further confirmed the statistical stability of our results (Fig 5 for the allele model; data not shown for the other models; S1DS3D Figs for the C282Y+H63D mutation).

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Fig 5. Sensitivity analysis of the association between the C282Y and H63D polymorphisms of HFE and the risks of diseases, including NAFLD, liver cirrhosis and HCC.

(A) Y vs C model for C282Y; (B) D vs H model for H63D.

https://doi.org/10.1371/journal.pone.0163423.g005

Discussion

Evidence was obtained from several relevant genome-wide association studies (GWAS) [16, 6870]. For instance, in 2010, Chalasani N, et al. performed GWAS to investigate the potential role of 324,623 allelic variants in 236 white women with NAFLD [69]. In 2013, Adams LA, et al. conducted another GWAS for NAFLD in 928-adolescents cohort [70]. The rs738409 polymorphism of PNPLA3 was identified in the GWAS of NAFLD [16]. However, the HFE gene was not included. In spite of this, polymorphisms of the HFE gene have been reported to be associated with NAFLD risk. For example, HFE H63D may contribute to the risk of NAFLD in the Korean population [33]. A positive association between HFE C282Y and NAFLD susceptibility was also observed [38]. Nevertheless, the role of HFE polymorphism in the occurrence of NAFLD remains unclear. For instance, there is no association between H63D of HFE and NASH risk in Italian patients [36].

In 2007, Ellervik C and colleagues reported that the HFE C282Y mutation might be linked to an increased risk of NASH under a homozygote meta-analysis model [23]. In 2011, Hernaez R, et al. performed a meta-analysis and failed to observe a positive association between HFE polymorphism and NAFLD susceptibility [12]. However, the results of our updated meta-analysis revealed that the HD genotype of H63D is more likely to be associated with NAFLD risk, and C282Y polymorphism may confer increased risk of NAFLD in the Caucasian population, which is partly consistent with the C282Y data of Ellervik C, et al. [23] but not Hernaez R, et al. [12]. How can this discrepancy be explained? The follow points were considered: (1) The two articles published by Sikorska K, et al. [19] and Valenti L, et al. [41] after 2011 and an additional three previously undetected articles [31, 34, 38] were added to our meta-analysis. In addition to a population-based control, the data of a hospital-based control were added to enhance the statistical power. For example, 20 patients with normal liver function tests and 20 patients infected with hepatitis C virus were considered as control groups based on the data of Zamin I, et al. [43]. (2) Sixteen case-control studies and 14 case-only studies were enrolled in the meta-analysis of Hernaez R, et al. [12]. Here, we utilized different evaluation criteria and focused on case-control studies that provided the data about the genotype distribution. The Passociation value, OR and 95% CI were calculated using Mantel-Haenszel statistics under the allele, homozygote, heterozygote, dominant and recessive models. (3) NAFLD is not a uniform clinical disease entity [5, 6, 71], and different case definitions and pathological diagnoses are probably the most important source of heterogeneity. We therefore extracted the data of the case features and performed subgroup analysis on the basis of specific NAFLD types. Unfortunately, we only extracted sufficient data for meta-analysis of NASH but not NAFLD-associated fatty liver, liver cirrhosis or cirrhosis. No remarkable association between HFE C282Y and NASH risk or reduced heterogeneity (data no shown) were observed in our further subgroup analysis for NASH under all genetic models. However, we found a positive association between the HD genotype of HFE H63D and increased susceptibility to overall NAFLD and specific NASH, particularly in the Asian population.

Progressive iron overload in the liver was considered a key factor for the presence of liver injury, chronic inflammation, fibrosis, cirrhosis, liver failure and cancer [72, 73]. The C282Y and H63D polymorphisms of the HFE gene were tightly associated with the presence of HH with impaired iron metabolism [18, 19]. Mild iron overload was associated with HFE C282Y mutation and NAFLD risk [38]. The HFE protein was reported to be capable of forming a stable complex with transferrin receptor (TFR) to inhibit the abnormal up-regulation of the level of iron in cells, whereas the HFE C282Y mutation impairs the process and leads to peripheral iron overload [44, 74, 75]. In our meta-analysis, we observed an association between HFE C282Y and H63D and NAFLD risk. Iron overload might contribute to this association by acting as a fundamental regulation factor.

Diverse conclusions on the role of HFE polymorphism in HCC risk have also been obtained. For instance, the C282Y heterozygous genotype was reported to be associated with susceptibility to HCC [48]. H63D was linked to increased HCC risk in the Moroccan population [62]. However, the data of Racchi O, et al. showed that the HFE gene polymorphisms failed to participate in the pathogenesis of HCC [64]. Several related meta-analyses have been conducted [13, 2426]. In 2010, Jin F, et al. reported an association between HCC susceptibility and C282Y, but not H63D, mutation in the European population [24]. Very recently, the meta-analysis of Lv YF, et al. showed that HFE C282Y mutation may be associated with increased HCC risk [25]. Additionally, another meta-analysis showed a positive association between HCC susceptibility and the YY homozygote genotype of C282Y but not the DD and HD genotypes of H63D [26]. Nevertheless, in 2015, Shen LL, et al. found that HFE H63D polymorphism might be involved in the aggressiveness of HCC [13]. In addition, conflicting data on the correlation between overall liver cirrhosis and HFE gene mutations were observed. For instance, the polymorphisms of the HFE gene are not essential for cryptogenic cirrhosis in the southern Iranian population [50]. C282Y might be linked to the risk of HCC in patients with alcoholic-related cirrhosis [24, 63]. H63D was reported to be associated with increased HCC risk in cirrhotic patients [65]. However, Boige V, et al. reported that the C282Y and H63D polymorphisms were not associated with increased susceptibility to HCC plus cirrhosis in patients [59]. Therefore, we performed an updated meta-analysis to better understand the genetic relationship between HFE mutations and the risks of HCC and liver cirrhosis. Our data demonstrated that C282Y and H63D are not associated with the risks of alcoholic, cryptogenic or viral-related liver cirrhosis. Moreover, HFE C282Y was significantly linked to the risk of HCC, while H63D was more likely to be involved in susceptibility to HCC without cirrhosis.

The disadvantages of our systematic review and meta-analysis are as follows. (1) The eligible articles contain relatively small sample sizes. For instance, only two case-control studies were enrolled in the meta-analysis of the Asian subgroup. (2) Four moderate-quality studies were included in our meta-analysis [19, 37, 55, 57]. The lack of sufficient information for the “case definition” or “representativeness of the cases” and the selection of a non-community control might contribute to this quality issue. (3) Additional unpublished articles, between-study heterogeneity and potential publication bias may distort our conclusions. (4) There are highly various etiologies for NAFLD, liver cirrhosis and HCC [3, 4, 6]. We failed to obtain efficient phenotype data and thus performed very limited stratified meta-analyses, which might contribute to the heterogeneity among studies. Additional well-powered studies are required to confirm the effect of multiple HFE mutations (C282Y, H63D and S65C) on the susceptibility to different types of NAFLD, liver cirrhosis and HCC.

Conclusion

In summary, our updated systematic review and meta-analysis confirmed the role of HFE C282Y in an increased HCC risk and provided new evidence that H63D is more likely to be associated with susceptibility to non-cirrhotic HCC in the African population. A significant correlation between HFE C282Y and H63D polymorphism and NAFLD susceptibility was obtained. Furthermore, we found that the HFE mutations failed to increase the odds of developing liver cirrhosis. The first evidence regarding the positive genetic relationship between compound heterozygosity for C282Y/H63D and the risks of NAFLD and HCC was demonstrated.

Supporting Information

S1 Fig. Meta-analysis of the genetic relationship between C282Y+H63D polymorphism and NAFLD risk.

(A) Forest plot analysis; (B) Begg’s test; (C) Egger’s test; (D) Sensitivity analysis.

https://doi.org/10.1371/journal.pone.0163423.s001

(TIF)

S2 Fig. Meta-analysis of the genetic relationship between C282Y+H63D polymorphism and liver cirrhosis risk.

(A) Forest plot analysis; (B) Begg’s test; (C) Egger’s test; (D) Sensitivity analysis.

https://doi.org/10.1371/journal.pone.0163423.s002

(TIF)

S3 Fig. Meta-analysis of the genetic relationship between C282Y+H63D polymorphism and HCC risk.

(A) Forest plot analysis; (B) Begg’s test; (C) Egger’s test; (D) Sensitivity analysis.

https://doi.org/10.1371/journal.pone.0163423.s003

(TIF)

S2 Table. Meta-analysis on genetic association studies checklist.

https://doi.org/10.1371/journal.pone.0163423.s005

(DOCX)

S3 Table. Electronic databases searching terms for meta-analysis.

https://doi.org/10.1371/journal.pone.0163423.s006

(DOCX)

S4 Table. Characteristics of studies included in the meta-analysis.

https://doi.org/10.1371/journal.pone.0163423.s007

(DOCX)

S5 Table. Genotype distribution of HFE C282Y polymorphism.

https://doi.org/10.1371/journal.pone.0163423.s008

(DOCX)

S6 Table. Genotype distribution of HFE H63D polymorphism.

https://doi.org/10.1371/journal.pone.0163423.s009

(DOCX)

S9 Table. Pooled analysis of the association between the HFE C282Y+H63D genotype frequencies and the risks of NAFLD, liver cirrhosis, and HCC.

https://doi.org/10.1371/journal.pone.0163423.s012

(DOCX)

Author Contributions

  1. Conceptualization: QY BXQ TH.
  2. Data curation: QY BXQ TH.
  3. Formal analysis: QY BXQ WLY FMW.
  4. Funding acquisition: TH.
  5. Investigation: QY BXQ WLY FMW.
  6. Methodology: QY BXQ WLY FMW.
  7. Project administration: TH.
  8. Resources: QY BXQ WLY FMW.
  9. Software: QY BXQ WLY FMW.
  10. Supervision: TH.
  11. Validation: QY BXQ WLY FMW.
  12. Visualization: QY BXQ TH.
  13. Writing – original draft: QY BXQ.
  14. Writing – review & editing: TH.

References

  1. 1. Tan H, Xu L, Liu X, Si S, Sun Y, Liu L, et al. Hepatocellular carcinoma in nonalcoholic fatty liver disease mimicking benign hemangioma: two case reports and literature review. Int J Clin Exp Pathol. 2015;8(11):15350–15355. Epub 2016/01/30. pmid:26823893; PubMed Central PMCID: PMCPmc4713679.
  2. 2. Khan FZ, Perumpail RB, Wong RJ, Ahmed A. Advances in hepatocellular carcinoma: Nonalcoholic steatohepatitis-related hepatocellular carcinoma. World J Hepatol. 2015;7(18):2155–2161. Epub 2015/09/04. pmid:26328027; PubMed Central PMCID: PMCPmc4550870.
  3. 3. Shevela EY, Starostina NM, Pal'tsev AI, Shipunov MV, Zheltova OI, Meledina IV, et al. Efficiency of Cell Therapy in Liver Cirrhosis. Bull Exp Biol Med. 2016. Epub 2016/02/24. pmid:26902361.
  4. 4. Plentz RR, Malek NP. Early Detection of Hepatocellular Carcinoma: How to Screen and Follow up Patients with Liver Cirrhosis According to the GERMAN S3 Guideline? Diagnostics (Basel). 2015;5(4):497–503. Epub 2016/02/09. pmid:26854167; PubMed Central PMCID: PMCPmc4728471.
  5. 5. Liu W, Baker RD, Bhatia T, Zhu L, Baker SS. Pathogenesis of nonalcoholic steatohepatitis. Cell Mol Life Sci. 2016. Epub 2016/02/20. pmid:26894897.
  6. 6. Basaranoglu M, Ormeci N. Nonalcoholic fatty liver disease: diagnosis, pathogenesis, and management. Turk J Gastroenterol. 2014;25(2):127–132. Epub 2014/07/09. pmid:25003670.
  7. 7. Lauret E, Rodriguez M, Gonzalez S, Linares A, Lopez-Vazquez A, Martinez-Borra J, et al. HFE gene mutations in alcoholic and virus-related cirrhotic patients with hepatocellular carcinoma. Am J Gastroenterol. 2002;97(4):1016–1021. Epub 2002/05/11. pmid:12003382.
  8. 8. Ozturk S, Dikici H, Dincer D, Luleci G, Keser I. Screening of the HFE Gene Mutations in Turkish Patients with Cryptogenic Cirrhosis and Hemochromatosis. Turkiye Klinikleri Tip Bilimleri Dergisi. 2010;30(6):1891–1895. pmid:WOS:000287053500015.
  9. 9. Sun MY, Zhang L, Shi SL, Lin JN. Associations between Methylenetetrahydrofolate Reductase (MTHFR) Polymorphisms and Non-Alcoholic Fatty Liver Disease (NAFLD) Risk: A Meta-Analysis. PLoS One. 2016;11(4):e0154337. Epub 2016/04/30. pmid:27128842; PubMed Central PMCID: PMCPmc4851382.
  10. 10. Motawi TK, Shaker OG, Ismail MF, Sayed NH. Genetic variants associated with the progression of hepatocellular carcinoma in hepatitis C Egyptian patients. Gene. 2013;527(2):516–520. Epub 2013/07/13. pmid:23845776.
  11. 11. Chen LZ, Hua-Xiang Xia H, Xin YN, Lin ZH, Xuan SY. TM6SF2 E167K Variant, a Novel Genetic Susceptibility Variant, Contributing to Nonalcoholic Fatty Liver Disease. J Clin Transl Hepatol. 2015;3(4):265–270. Epub 2016/01/26. pmid:26807382; PubMed Central PMCID: PMCPmc4721894.
  12. 12. Hernaez R, Yeung E, Clark JM, Kowdley KV, Brancati FL, Kao WH. Hemochromatosis gene and nonalcoholic fatty liver disease: a systematic review and meta-analysis. J Hepatol. 2011;55(5):1079–1085. Epub 2011/03/01. pmid:21354231; PubMed Central PMCID: PMCPmc3611963.
  13. 13. Shen LL, Gu DY, Zhao TT, Tang CJ, Xu Y, Chen JF. Implicating the H63D polymorphism in the HFE gene in increased incidence of solid cancers: a meta-analysis. Genet Mol Res. 2015;14(4):13735–13745. Epub 2015/11/05. pmid:26535689.
  14. 14. Macaluso FS, Maida M, Petta S. Genetic background in nonalcoholic fatty liver disease: A comprehensive review. World J Gastroenterol. 2015;21(39):11088–11111. pmid:26494964; PubMed Central PMCID: PMC4607907.
  15. 15. Lim JW, Dillon J, Miller M. Proteomic and genomic studies of non-alcoholic fatty liver disease—clues in the pathogenesis. World J Gastroenterol. 2014;20(26):8325–8340. Epub 2014/07/16. pmid:25024592; PubMed Central PMCID: PMCPmc4093687.
  16. 16. Speliotes EK, Yerges-Armstrong LM, Wu J, Hernaez R, Kim LJ, Palmer CD, et al. Genome-wide association analysis identifies variants associated with nonalcoholic fatty liver disease that have distinct effects on metabolic traits. PLoS Genet. 2011;7(3):e1001324. Epub 2011/03/23. pmid:21423719; PubMed Central PMCID: PMCPmc3053321.
  17. 17. Feder JN, Gnirke A, Thomas W, Tsuchihashi Z, Ruddy DA, Basava A, et al. A novel MHC class I-like gene is mutated in patients with hereditary haemochromatosis. Nat Genet. 1996;13(4):399–408. Epub 1996/08/01. pmid:8696333.
  18. 18. Cardoso CS, de Sousa M. HFE, the MHC and hemochromatosis: paradigm for an extended function for MHC class I. Tissue Antigens. 2003;61(4):263–275. Epub 2003/05/20. pmid:12753664.
  19. 19. Sikorska K, Stalke P, Romanowski T, Rzepko R, Bielawski KP. Liver steatosis correlates with iron overload but not with HFE gene mutations in chronic hepatitis C. Hepatobiliary Pancreat Dis Int. 2013;12(4):377–384. Epub 2013/08/09. pmid:23924495.
  20. 20. Xia J, Xu H, Jiang H, Xie J. The association between the C282Y and H63D polymorphisms of HFE gene and the risk of Parkinson's disease: A meta-analysis. Neurosci Lett. 2015;595:99–103. Epub 2015/04/12. pmid:25863172.
  21. 21. Sokolova EA, Shadrina AS, Sevost'ianova KS, Shevela AI, Soldatsky EY, Seliverstov EI, et al. HFE p.C282Y gene variant is associated with varicose veins in Russian population. Clin Exp Med. 2015. Epub 2015/09/30. pmid:26416403.
  22. 22. Lian J, Xu L, Huang Y, Le Y, Jiang D, Yang X, et al. Meta-analyses of HFE variants in coronary heart disease. Gene. 2013;527(1):167–173. Epub 2013/06/25. pmid:23792061.
  23. 23. Ellervik C, Birgens H, Tybjaerg-Hansen A, Nordestgaard BG. Hemochromatosis genotypes and risk of 31 disease endpoints: meta-analyses including 66,000 cases and 226,000 controls. Hepatology. 2007;46(4):1071–1080. Epub 2007/09/11. pmid:17828789.
  24. 24. Jin F, Qu LS, Shen XZ. Association between C282Y and H63D mutations of the HFE gene with hepatocellular carcinoma in European populations: a meta-analysis. J Exp Clin Cancer Res. 2010;29:18. Epub 2010/03/04. pmid:20196837; PubMed Central PMCID: PMCPmc2845109.
  25. 25. Lv YF, Chang X, Hua RX, Yan GN, Meng G, Liao XY, et al. The risk of new-onset cancer associated with HFE C282Y and H63D mutations: evidence from 87,028 participants. J Cell Mol Med. 2016. pmid:26893171.
  26. 26. Xiao-Bing H, Lu Z, Hong G, Ping L, Guanghui L, Hongming L, et al. Meta analysis on relationship between distributions of C282Y and H63D alleles and genotypes and hepatocellular carcinoma. Minerva Med. 2016. Epub 2016/01/15. pmid:26765307.
  27. 27. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6(7):e1000097. Epub 2009/07/22. pmid:19621072; PubMed Central PMCID: PMCPmc2707599.
  28. 28. Stang A. Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses. Eur J Epidemiol. 2010;25(9):603–605. Epub 2010/07/24. pmid:20652370.
  29. 29. Bonkovsky HL, Jawaid Q, Tortorelli K, LeClair P, Cobb J, Lambrecht RW, et al. Non-alcoholic steatohepatitis and iron: increased prevalence of mutations of the HFE gene in non-alcoholic steatohepatitis. J Hepatol. 1999;31(3):421–429. Epub 1999/09/17. pmid:10488699.
  30. 30. Chitturi S, Weltman M, Farrell GC, McDonald D, Kench J, Liddle C, et al. HFE mutations, hepatic iron, and fibrosis: ethnic-specific association of NASH with C282Y but not with fibrotic severity. Hepatology. 2002;36(1):142–149. Epub 2002/06/27. pmid:12085358.
  31. 31. Dhillon BK, Das R, Garewal G, Chawla Y, Dhiman RK, Das A, et al. Frequency of primary iron overload and HFE gene mutations (C282Y, H63D and S65C) in chronic liver disease patients in north India. World J Gastroenterol. 2007;13(21):2956–2959. Epub 2007/06/26. pmid:17589946; PubMed Central PMCID: PMCPmc4171148.
  32. 32. George DK, Goldwurm S, MacDonald GA, Cowley LL, Walker NI, Ward PJ, et al. Increased hepatic iron concentration in nonalcoholic steatohepatitis is associated with increased fibrosis. Gastroenterology. 1998;114(2):311–318. Epub 1998/02/07. pmid:9453491.
  33. 33. Lee SH, Jeong SH, Lee D, Lee JH, Hwang SH, Cho YA, et al. An epidemiologic study on the incidence and significance of HFE mutations in a Korean cohort with nonalcoholic fatty liver disease. J Clin Gastroenterol. 2010;44(7):e154–161. Epub 2010/03/11. pmid:20216079.
  34. 34. Lee SH, Kim JW, Shin SH, Kang KP, Choi HC, Choi SH, et al. HFE gene mutations, serum ferritin level, transferrin saturation, and their clinical correlates in a Korean population. Dig Dis Sci. 2009;54(4):879–886. Epub 2008/08/07. pmid:18683048.
  35. 35. Lin TJ, Lin CL, Wang CS, Liu SO, Liao LY. Prevalence of HFE mutations and relation to serum iron status in patients with chronic hepatitis C and patients with nonalcoholic fatty liver disease in Taiwan. World J Gastroenterol. 2005;11(25):3905–3908. Epub 2005/07/02. pmid:15991291; PubMed Central PMCID: PMCPmc4504894.
  36. 36. Neri S, Pulvirenti D, Signorelli S, Ignaccolo L, Tsami A, Mauceri B, et al. The HFE gene heterozygosis H63D: a cofactor for liver damage in patients with steatohepatitis? Epidemiological and clinical considerations. Intern Med J. 2008;38(4):254–258. Epub 2007/10/06. pmid:17916170.
  37. 37. Simsek H, Balaban YH, Sumer H, Yilmaz E, Tatar G. HFE mutations analysis of Turkish patients with nonalcoholic steatohepatitis. Dig Dis Sci. 2006;51(10):1723–1724. Epub 2006/09/12. pmid:16964543.
  38. 38. Valenti L, Dongiovanni P, Fracanzani AL, Santorelli G, Fatta E, Bertelli C, et al. Increased susceptibility to nonalcoholic fatty liver disease in heterozygotes for the mutation responsible for hereditary hemochromatosis. Digestive and Liver Disease. 2003;35(3):172–178. pmid:12779071
  39. 39. Valenti L, Dongiovanni P, Piperno A, Fracanzani AL, Maggioni M, Rametta R, et al. Alpha 1-antitrypsin mutations in NAFLD: high prevalence and association with altered iron metabolism but not with liver damage. Hepatology. 2006;44(4):857–864. Epub 2006/09/29. pmid:17006922.
  40. 40. Valenti L, Fracanzani AL, Bugianesi E, Dongiovanni P, Galmozzi E, Vanni E, et al. HFE genotype, parenchymal iron accumulation, and liver fibrosis in patients with nonalcoholic fatty liver disease. Gastroenterology. 2010;138(3):905–912. Epub 2009/11/26. pmid:19931264.
  41. 41. Valenti L, Rametta R, Dongiovanni P, Motta BM, Canavesi E, Pelusi S, et al. The A736V TMPRSS6 polymorphism influences hepatic iron overload in nonalcoholic fatty liver disease. PLoS One. 2012;7(11):e48804. Epub 2012/11/13. pmid:23144979; PubMed Central PMCID: PMCPmc3489825.
  42. 42. Yoneda M, Nozaki Y, Endo H, Mawatari H, Iida H, Fujita K, et al. Serum ferritin is a clinical biomarker in Japanese patients with nonalcoholic steatohepatitis (NASH) independent of HFE gene mutation. Dig Dis Sci. 2010;55(3):808–814. Epub 2009/03/10. pmid:19267193.
  43. 43. Zamin I Jr, Mattos AA, Mattos AZ, Migon E, Bica C, Alexandre CO. Prevalence of the hemochromatosis gene mutation in patients with nonalcoholic steatohepatitis and correlation with degree of liver fibrosis. Arq Gastroenterol. 2006;43(3):224–228. Epub 2006/12/13. pmid:17160239.
  44. 44. Beckman LE, Hagerstrand I, Stenling R, Van Landeghem GF, Beckman L. Interaction between haemochromatosis and transferrin receptor genes in hepatocellular carcinoma. Oncology. 2000;59(4):317–322. Epub 2000/11/30. 12189. pmid:11096344.
  45. 45. Frenzer A, Rudzki Z, Norton ID, Butler WJ, Roberts-Thomson IC. Heterozygosity of the haemochromatosis mutation, C282Y, does not influence susceptibility to alcoholic cirrhosis. Scand J Gastroenterol. 1998;33(12):1324. Epub 1999/02/04. pmid:9930398.
  46. 46. Gharib AF, Karam RA, Pasha HF, Radwan MI, Elsawy WH. Polymorphisms of hemochromatosis, and alpha-1 antitrypsin genes in Egyptian HCV patients with and without hepatocellular carcinoma. Gene. 2011;489(2):98–102. Epub 2011/09/20. pmid:21925577.
  47. 47. Gleeson D, Evans S, Bradley M, Jones J, Peck RJ, Dube A, et al. HFE genotypes in decompensated alcoholic liver disease: Phenotypic expression and comparison with heavy drinking and with normal controls. American Journal of Gastroenterology. 2006;101(2):304–310. pmid:WOS:000235040500018.
  48. 48. Hellerbrand C, Poppl A, Hartmann A, Scholmerich J, Lock G. HFE C282Y heterozygosity in hepatocellular carcinoma: evidence for an increased prevalence. Clin Gastroenterol Hepatol. 2003;1(4):279–284. Epub 2004/03/16. pmid:15017669.
  49. 49. Jain S, Agarwal S, Tamhankar P, Verma P, Choudhuri G. Lack of association of primary iron overload and common HFE gene mutations with liver cirrhosis in adult Indian population. Indian J Gastroenterol. 2011;30(4):161–165. Epub 2011/08/09. pmid:21822737.
  50. 50. Jowkar Z, Geramizadeh B, Shariat M. Frequency of Two Common HFE Gene Mutations (C282Y and H63D) in a Group of Iranian Patients With Cryptogenic Cirrhosis. Hepat Mon. 2011;11(11):887–889. Epub 2012/02/07. pmid:22308152; PubMed Central PMCID: PMCPmc3269056.
  51. 51. Mah YH, Kao JH, Liu CJ, Chen CL, Chen PJ, Lai MY, et al. Prevalence and clinical implications of HFE gene mutations (C282Y and H63D) in patients with chronic hepatitis B and C in Taiwan. Liver Int. 2005;25(2):214–219. Epub 2005/03/23. pmid:15780041.
  52. 52. Neghina AM, Anghel A, Sporea I, Popescu A, Neghina R, Collins A, et al. Mutant HFE genotype leads to significant iron overload in patients with liver diseases from western Romania. J Appl Genet. 2009;50(2):173–176. Epub 2009/05/13. pmid:19433916.
  53. 53. Panigrahi I, Ahmad F, Kapoor R, Sharma PK, Makharia G, Saxena R. Evidence for non-HFE linked hemochromatosis in Asian Indians. Indian J Med Sci. 2006;60(12):491–495. Epub 2006/11/30. pmid:17130663.
  54. 54. Pfeiffenberger J, Gotthardt DN, Herrmann T, Seessle J, Merle U, Schirmacher P, et al. Iron metabolism and the role of HFE gene polymorphisms in Wilson disease. Liver Int. 2012;32(1):165–170. Epub 2011/11/22. pmid:22098612.
  55. 55. Sikorska K, Romanowski T, Stalke P, Izycka-Świeszewska E, Bielawski KP. Iron overload and HFE gene mutations in polish patients with liver cirrhosis. Hepatobiliary and Pancreatic Diseases International. 2011;10(3):270–275. pmid:21669570
  56. 56. Starcevic Cizmarevic N, Stepec S, Ristic S, Milic S, Brajenovic-Milic B, Stimac D, et al. Hemochromatosis gene mutations in patients with alcoholic cirrhosis. Clin Genet. 2006;70(3):257–259. Epub 2006/08/23. pmid:16922731.
  57. 57. Willis G, Wimperis JZ, Lonsdale R, Fellows IW, Watson MA, Skipper LM, et al. Incidence of liver disease in people with HFE mutations. Gut. 2000;46(3):401–404. Epub 2000/02/15. pmid:10673304; PubMed Central PMCID: PMCPmc1727850.
  58. 58. Yonal O, Hatirnaz O, Akyuz F, Ozbek U, Demir K, Kaymakoglu S, et al. HFE gene mutation, chronic liver disease, and iron overload In Turkey. Dig Dis Sci. 2007;52(11):3298–3302. Epub 2007/04/06. pmid:17410459.
  59. 59. Boige V, Castera L, de Roux N, Ganne-Carrie N, Ducot B, Pelletier G, et al. Lack of association between HFE gene mutations and hepatocellular carcinoma in patients with cirrhosis. Gut. 2003;52(8):1178–1181. Epub 2003/07/17. pmid:12865278; PubMed Central PMCID: PMCPmc1773773.
  60. 60. Campo S, Restuccia T, Villari D, Raffa G, Cucinotta D, Squadrito G, et al. Analysis of haemochromatosis gene mutations in a population from the Mediterranean Basin. Liver. 2001;21(4):233–236. Epub 2001/07/17. pmid:11454185.
  61. 61. Cauza E, Peck-Radosavljevic M, Ulrich-Pur H, Datz C, Gschwantler M, Schoniger-Hekele M, et al. Mutations of the HFE gene in patients with hepatocellular carcinoma. Am J Gastroenterol. 2003;98(2):442–447. Epub 2003/02/20. pmid:12591066.
  62. 62. Ezzikouri S, El Feydi AE, El Kihal L, Afifi R, Benazzouz M, Hassar M, et al. Prevalence of common HFE and SERPINA1 mutations in patients with hepatocellular carcinoma in a Moroccan population. Arch Med Res. 2008;39(2):236–241. Epub 2008/01/01. pmid:18164971.
  63. 63. Nahon P, Sutton A, Rufat P, Ziol M, Thabut G, Schischmanoff PO, et al. Liver iron, HFE gene mutations, and hepatocellular carcinoma occurrence in patients with cirrhosis. Gastroenterology. 2008;134(1):102–110. Epub 2007/12/07. pmid:18061182.
  64. 64. Racchi O, Mangerini R, Rapezzi D, Gaetani GF, Nobile MT, Picciotto A, et al. Mutations of the HFE gene and the risk of hepatocellular carcinoma. Blood Cells Mol Dis. 1999;25(5–6):350–353. Epub 2000/02/08. pmid:10660482.
  65. 65. Ropero P, Briceno O, Lopez-Alonso G, Agundez JA, Gonzalez Fernandez FA, Garcia-Hoz F, et al. [The H63D mutation in the HFE gene is related to the risk of hepatocellular carcinoma]. Rev Esp Enferm Dig. 2007;99(7):376–381. Epub 2007/11/02. pmid:17973580.
  66. 66. Shi WJ, Chen H, Zhou B, Cheng J. [Association of mutations of HFE gene and hepatocellular carcinoma following chronic hepatitis B]. Zhonghua Gan Zang Bing Za Zhi. 2005;13(9):682–684. Epub 2005/09/22. pmid:16174459.
  67. 67. Willis G, Bardsley V, Fellows IW, Lonsdale R, Wimperis JZ, Jennings BA. Hepatocellular carcinoma and the penetrance of HFE C282Y mutations: a cross sectional study. BMC Gastroenterol. 2005;5:17. Epub 2005/06/03. pmid:15929796; PubMed Central PMCID: PMCPmc1175847.
  68. 68. Romeo S, Kozlitina J, Xing C, Pertsemlidis A, Cox D, Pennacchio LA, et al. Genetic variation in PNPLA3 confers susceptibility to nonalcoholic fatty liver disease. Nat Genet. 2008;40(12):1461–1465. Epub 2008/09/30. pmid:18820647; PubMed Central PMCID: PMCPmc2597056.
  69. 69. Chalasani N, Guo X, Loomba R, Goodarzi MO, Haritunians T, Kwon S, et al. Genome-wide association study identifies variants associated with histologic features of nonalcoholic Fatty liver disease. Gastroenterology. 2010;139(5):1567–1576, 1576.e1561-1566. Epub 2010/08/17. pmid:20708005; PubMed Central PMCID: PMCPmc2967576.
  70. 70. Adams LA, White SW, Marsh JA, Lye SJ, Connor KL, Maganga R, et al. Association between liver-specific gene polymorphisms and their expression levels with nonalcoholic fatty liver disease. Hepatology. 2013;57(2):590–600. Epub 2012/12/06. pmid:23213074.
  71. 71. Eslam M, George J. Genetic and epigenetic mechanisms of NASH. Hepatol Int. 2016;10(3):394–406. Epub 2015/12/20. pmid:26683320.
  72. 72. Fargion S, Mattioli M, Fracanzani AL, Fiorelli G. Iron and liver diseases. Can J Gastroenterol. 2000;14 Suppl D:89d–92d. Epub 2000/12/08. pmid:11110619.
  73. 73. Pietrangelo A. Iron and the liver. Liver Int. 2016;36 Suppl 1:116–123. Epub 2016/01/05. pmid:26725908.
  74. 74. Feder JN, Penny DM, Irrinki A, Lee VK, Lebron JA, Watson N, et al. The hemochromatosis gene product complexes with the transferrin receptor and lowers its affinity for ligand binding. Proc Natl Acad Sci U S A. 1998;95(4):1472–1477. Epub 1998/03/21. pmid:9465039; PubMed Central PMCID: PMCPmc19050.
  75. 75. Goswami T, Andrews NC. Hereditary hemochromatosis protein, HFE, interaction with transferrin receptor 2 suggests a molecular mechanism for mammalian iron sensing. J Biol Chem. 2006;281(39):28494–28498. Epub 2006/08/09. pmid:16893896.