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Associations of Hydroxysteroid 17-beta Dehydrogenase 13 Variants with Liver Histology in Chinese Patients with Metabolic-associated Fatty Liver Disease

  • Wen-Yue Liu1,#,
  • Mohammed Eslam2,#,
  • Kenneth I. Zheng3,
  • Hong-Lei Ma3,
  • Rafael S. Rios3,
  • Min-Zhi Lv4,
  • Gang Li3,
  • Liang-Jie Tang3,
  • Pei-Wu Zhu5,
  • Xiao-Dong Wang3,6,
  • Christopher D. Byrne7,
  • Giovanni Targher8,
  • Jacob George2,* and
  • Ming-Hua Zheng3,6,9,* 
Journal of Clinical and Translational Hepatology   2021;9(2):194-202

doi: 10.14218/JCTH.2020.00151

Received:

Revised:

Accepted:

Published online:

 Author information

Citation: Liu WY, Eslam M, Zheng KI, Ma HL, Rios RS, Lv MZ, et al. Associations of Hydroxysteroid 17-beta Dehydrogenase 13 Variants with Liver Histology in Chinese Patients with Metabolic-associated Fatty Liver Disease. J Clin Transl Hepatol. 2021;9(2):194-202. doi: 10.14218/JCTH.2020.00151.

Abstract

Background and Aims

In Europeans, variants in the hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13) gene impact liver histology in metabolic-associated fatty liver disease (MAFLD). The impact of these variants in ethnic Chinese is unknown. The aim of this study was to investigate the potential associations in Chinese patients.

Methods

In total, 427 Han Chinese with biopsy-confirmed MAFLD were enrolled. Two single nucleotide polymorphisms in HSD17B13 were genotyped: rs72613567 and rs6531975. Logistic regression was used to test the association between the single nucleotide polymorphisms and liver histology.

Results

In our cohort, the minor allele TA of the rs72613567 variant was related to an increased risk of fibrosis [odds ratio (OR): 2.93 (1.20–7.17), p=0.019 for the additive model; OR: 3.32 (1.39–7.91), p=0.007 for the recessive model], representing an inverse association as compared to the results from European cohorts. In contrast, we observed a protective effect on fibrosis for the minor A allele carriers of the HSD17B13 rs6531975 variant [OR: 0.48 (0.24–0.98), p=0.043 for the additive model; OR: 0.62 (0.40–0.94), p=0.025 for the dominant model]. HSD17B13 variants were only associated with fibrosis but no other histological features. Furthermore, HSD17B13 rs6531975 modulated the effect of PNPLA3 rs738409 on hepatic steatosis.

Conclusions

HSD17B13 rs72613567 is a risk variant for fibrosis in a Han Chinese MAFLD population but with a different direction for allelic association to that seen in Europeans. These data exemplify the need for studying diverse populations in genetic studies in order to fine map genome-wide association studies signals.

Keywords

Metabolic-associated fatty liver disease (MAFLD), Nonalcoholic fatty liver disease (NAFLD), Hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13), Single nucleotide polymorphism (SNP)

Introduction

Metabolic-associated fatty liver disease (MAFLD) is recognized as a leading cause of liver-related morbidity and mortality.1,2 In China, the MAFLD burden is increasing, with prevalence rising from 18% to 29% in the last decade.3 MAFLD comprises a spectrum of disease, ranging from simple steatosis or metabolic-associated fatty liver (MAFL) to the presence of steatohepatitis with varying degrees of fibrosis and cirrhosis.4 MAFLD arises from “multiple hits”, with genes acting as important modifiers of the clinical phenotype.5 Our understanding of the underpinnings of MAFLD has been enhanced by numerous genetic association studies, and all of the polymorphisms identified to date explain only 10–20% of disease heritability.6,7

It is broadly acknowledged that there is overrepresentation of subjects of European ancestry in human genetics research, with ∼79% of all genome-wide association studies (GWAS) participants being of European descent. This overrepresentation hinders a complete understanding of the human genetic architecture. Moreover, it can also have a negative impact, including prediction accuracies between 1.6-4.9-fold lower for other ethnicities than Europeans.8 Hence, increasing the representation of diverse populations and studying other ethnicities has become a research priority.

Several variants in the hydroxysteroid 17-beta dehydrogenase 13 (HSD17B13) gene encoding a hepatic lipid droplet protein have been identified to impact the histological features of MAFLD. However, the impact of HSD17B13 gene variants on MAFLD histology among those of Chinese ancestry is unknown. Notably, allele frequencies, haplotype patterns and the effect size of polymorphisms vary considerably across populations and ethnicities.6 As HSD17B13 has been proposed as a therapeutic target for MAFLD, it is pivotal to explore whether the effect of this variant observed in Caucasian populations extends to other populations, as also to the effect size.

It is known that the genetic association of variants in HSD17B13 with the histological features of MAFLD is complex, with different potentially causative single nucleotide polymorphisms (SNPs) and various SNPs associated with different phenotypic patterns. For example, alleles of rs6834314 and rs72613567 associate with decreased injury and with increased hepatic fat.9 However, there are other studies that show no association of rs72613567 with steatosis.10,11 Noncoding SNPs (e.g., rs6531975) not in linkage disequilibrium with rs72613567 have also been associated with decreased hepatic fat.9 Adding to this complexity, a recent study of 487 patients suggested that those harboring the ‘protective’ TA-allele of rs72613567 have a numerically increased risk for mortality, liver-related death and hepatic decompensation.12 Likewise, while some reports have suggested that there is a potential interaction between HSD17B13 and variants in the patatin-like phospholipase domain containing protein 3 (PNPLA3) gene in MAFLD, subsequent reports have cited a failure to discern an association.13,14

Given these controversies, the aims of this study were 1) to explore the role of variants in the HSD17B13 gene in a cohort of Han Chinese with biopsy-confirmed MAFLD, 2) to clarify the role of the variants on the various morphological features of MAFLD, and 3) to discern if there is any interaction between the variants and variants in PNPLA3.

Methods

Study population

We recruited 427 consecutive Han Chinese patients with biopsy-confirmed MAFLD from the PERSONS cohort (2017.01–2019.05). The definition of MAFLD was based on the criteria proposed by an international expert panel.15 The study cohort included patients from a previously published study as well as additional subjects.16 To ascertain the effects of the HSD17B13 variant on liver disease solely due to MAFLD, patients with other causes of liver disease (including alcohol use disorder or viral hepatitis) were excluded. Briefly, all consecutive patients, aged ≥18, with biopsy-proven MAFLD, and without alternative causes of liver disease were recruited to the study.

The study protocol was approved by the ethics committee of the First Affiliated Hospital of Wenzhou Medical University (2016-246, 1 December 2016) and registered in the Chinese Clinical Trial Registry (ChiCTR-EOC-17013562). Written informed consent was obtained from each subject before their participation in the study. Patient identifiers were anonymized and replaced by the health examination number.

Clinical and biochemical data

Clinical and biochemical data were collected from all patients within 24 hours of liver biopsy. Body mass index (BMI) was calculated as weight (kg) divided by the square of height (m). Insulin resistance (IR) was estimated according by the homoeostasis model assessment (commonly referred to as HOMA).17 Diagnosis of diabetes was based on criteria of the American Diabetes Association.18

Assessment of liver histology

Liver biopsies were performed using a 16-gauge needle under ultrasound guidance. The histology was reviewed by a single liver pathologist (X.D. Wang) who was blinded to the clinical and biochemical data. Histologic scoring was based on the Activity Score.19 Steatohepatitis was diagnosed as a score ≥4 and a score of at least one for each feature of steatosis, ballooning, and lobular inflammation. Severe steatosis, severe ballooning and severe lobular inflammation were defined if their scores were ≥2.

Genetic analysis

Genotyping for the HSD17B13 (rs72613567 and rs6531975) and PNPLA3 (rs738409) variants were performed using the MassARRAY (Agena Biosciences, San Diego, CA, USA) or TaqMan assay (Bio-Rad, Hercules, CA, USA) platforms, according to the manufacturer’s protocol. For the purpose of genotyping, each sample used approximately 20 ng of genomic DNA. Locus-specific PCR and detection primers were designed using Assay Design Suite v3.1.

Statistical analysis

Statistical analyses were performed using R software (v3.5.2; R Foundation for Statistical Computing, Vienna, Austria) and SPSS 19.0 (SPSS Inc., Armonk, NY, USA). Continuous variables were expressed as mean±standard deviation and compared using the one-way analysis of variance test. Categorical variables were expressed as frequency (%) and compared using the chi-square test. The Hardy-Weinberg equilibrium was assessed using the chi-square test. Multivariate logistic regression models were undertaken to test the association between the aforementioned SNPs and liver histology features. A p-value <0.05 was considered to be statistically significant.

Results

Patient characteristics

The study comprised 427 consecutive biopsy-confirmed MAFLD patients; their clinical, biochemical, and histological features are depicted in Supplementary Table 1. The average age was 41 years, with 73.8% being male. About 287 (67.2%) had fibrosis (≥F1), 226 (52.9%) had severe steatosis (S2-S3), 157 (36.8%) had severe ballooning (B2) and 84 (19.7%) had severe inflammation (A2-A3).

Table 1

Baseline characteristics of biopsy-confirmed MAFLD patients according to rs72613567 genotypes

T/T (n=198)T/TA (n=176)TA/TA (n=45)p-value
Age in years40.2±11.941.4±11.543.1±14.80.299
Male sex, %150 (75.8%)126 (71.6%)33 (73.3%)0.657
Diabetes, %63 (31.8%)54 (30.7%)18 (40.0%)0.484
Hypertension, %74 (37.4%)59 (33.5%)22 (48.9%)0.161
Waist circumference in cm92.2±9.090.6±8.791.7±6.80.212
BMI in kg/m227.0±3.526.5±3.326.3±2.90.255
HOMA-IR score5.3±8.45.1±6.66.5±7.50.541
Platelet count as 109/L242.2±61.0246.7±56.2253.1±84.60.520
Hemoglobin A1c, %6.0±1.36.2±1.56.3±1.50.427
Fasting glucose in mmol/L5.7±1.55.5±1.26.2±2.40.012
Total cholesterol in mmol/L5.2±1.34.9±1.15.0±1.00.100
Triglycerides in mmol/L2.4±1.72.0±1.12.3±1.30.044
HDL-cholesterol in mmol/L1.0±0.21.0±0.21.1±0.40.019
LDL-cholesterol in mmol/L3.1±1.03.0±0.92.9±0.80.331
Albumin in g/L46.4±4.246.4±3.446.2±3.60.957
ALT in U/L83.4±79.967.9±56.970.6±46.60.079
AST in U/L50.4±35.745.2±35.040.8±20.60.139
GGT in U/L75.8±83.768.7±108.984.6±98.20.567
Creatinine in µmol/L67.1±14.366.1±12.970.6±17.40.159
Uric acid in µmol/L395.7±102.9385.8±108.1398.2±120.30.615
PNPLA3 rs7384090.256
  C/C56 (28.7%)51 (29.7%)16 (35.6%)
  C/G101 (51.8%)73 (42.4%)19 (42.2%)
  G/G38 (19.5%)48 (27.9%)10 (22.2%)

Genotype distribution, Hardy-Weinberg equilibrium calculations

Two SNPs in HSD17B13 were genotyped: rs72613567 and rs6531975. The genotype distributions of rs72613567 and rs6531975 in HSD17B13 were in Hardy-Weinberg equilibrium (all, p>0.05). The minor allele frequency (MAF) for rs72613567 and rs6531975 was 0.32 and 0.30 in our cohort, respectively. Each of these MAFs is close to the MAF in general East Asian population in the 1000 Genomes Project.20 The overall genotype distribution of rs72613567 T/T, T/TA and TA/TA was 47.3%, 42.0% and 10.7%, while the distribution of rs6531975 G/G, G/A and A/A was 49.8%, 40.5% and 9.8%, respectively.

Clinical and laboratory characteristics stratified by HSD17B13 variants

The baseline characteristics of study participants according to rs72613567 genotypes is presented in Table 1. There were significant differences in levels of fasting glucose, triglycerides and high-density lipoprotein cholesterol among rs72613567 genotypes (all, p<0.05). Table 2 shows the baseline characteristics of study participants according to rs6531975 genotypes. No significant differences were observed among the rs6531975 genotypes.

Table 2

Baseline characteristics of biopsy-confirmed MAFLD patients according to rs6531975 genotypes

G/G (n=209)G/A (n=170)A/A (n=41)p-value
Age in years41.8±12.340.6±11.238.9±13.80.300
Male sex, %160 (76.6%)122 (71.8%)27 (65.9%)0.287
Diabetes, %61 (29.2%)60 (35.3%)12 (29.3%)0.420
Hypertension, %74 (35.4%)67 (39.4%)14 (34.1%)0.672
Waist circumference in cm91.6±7.991.2±9.390.8±9.80.824
BMI in kg/m226.5±3.126.8±3.626.7±3.50.690
HOMA-IR score5.8±8.05.2±8.84.3±3.50.472
Platelet count as 109/L246.0±62.3243.9±60.9257.4±65.10.457
Hemoglobin A1c, %6.1±1.46.1±1.45.9±1.30.537
Fasting glucose in mmol/L5.7±1.65.7±1.55.4±1.10.440
Total cholesterol in mmol/L5.0±1.15.1±1.15.3±1.60.324
Triglycerides in mmol/L2.2±1.42.4±1.62.1±1.00.284
HDL-cholesterol in mmol/L1.0±0.21.0±0.21.0±0.20.665
LDL-cholesterol in mmol/L3.0±0.93.0±0.93.4±1.20.061
Albumin in g/L46.1±3.646.5±4.346.7±3.10.412
ALT in U/L70.3±53.481.2±93.184.3±73.50.275
AST in U/L44.1±30.150.2±40.851.0±35.70.193
GGT in U/L72.6±103.376.7±96.960.9±41.70.636
Creatinine in µmol/L68.0±13.066.4±15.263.5±13.70.137
Uric acid in µmol/L390.8±100.9391.6±112.9412.2±115.70.489
PNPLA3 rs7384090.684
  C/C62 (30.1%)48 (29.1%)14 (34.1%)
  C/G93 (45.1%)83 (50.3%)16 (39.0%)
  G/G51 (24.8%)34 (20.6%)11 (26.8%)

HSD17B13 variants and hepatic steatosis

The proportion of severe steatosis in rs72613567 T/T, T/TA and TA/TA was 103 (52.0%), 91 (51.7%)and 27 (60.0%) respectively, while the proportion of severe steatosis in rs6531975 G/G, G/A and A/A was 113 (54.1%), 84 (49.4%) and 24 (58.5%) respectively (Table 3). No association between HSD17B13 variants and severe steatosis was observed in multivariate logistic regression model (Table 4).

Table 3

Liver histology features of biopsy-confirmed MAFLD patients according to HSD17B13 genotypes

HSD17B13 rs72613567
HSD17B13 rs6531975
T/T (n=198)T/TA (n=176)TA/TA (n=45)p-valueG/G (n=209)G/A (n=170)A/A (n=41)p-value
Steatosis, n (%)0.5860.484
  Mild steatosis: <295 (48.0%)85 (48.3%)18 (40.0%)96 (45.9%)86 (50.6%)17 (41.5%)
  Severe steatosis: ≥2103 (52.0%)91 (51.7%)27 (60.0%)113 (54.1%)84 (49.4%)24 (58.5%)
Hepatocyte ballooning, n (%)0.2260.401
  Mild ballooning: <2125 (63.1%)118 (67.0%)24 (53.3%)130 (62.2%)107 (62.9%)30 (73.2%)
  Severe ballooning: =273 (36.9%)58 (33.0%)21 (46.7%)79 (37.8%)63 (37.1%)11 (26.8%)
Lobular inflammation, n (%)0.3860.939
  Mild inflammation: <2163 (82.3%)141 (80.1%)33 (73.3%)169 (80.9%)135 (79.4%)33 (80.5%)
  Severe inflammation: ≥235 (17.7%)35 (19.9%)12 (26.7%)40 (19.1%)35 (20.6%)8 (19.5%)
Presence of fibrosis, n (%)135 (68.2%)111 (63.1%)38 (84.4%)0.023150 (71.8%)109 (64.1%)23 (56.1%)0.082
Table 4

Association between HSD17B13 variants and liver histology features in Chinese MAFLD patients

SNPSevere steatosis
Severe ballooning
Severe inflammation
Presence of fibrosis
OR95% CIpOR95% CIpOR95% CIpOR95% CIp
HSD17B13 rs72613567
  Additive model
    T/Tref.ref.ref.ref.
    T/TA1.240.78–1.960.3680.930.60–1.440.7371.240.72–2.160.4370.770.49–1.200.252
    TA/TA1.620.77–3.420.2031.370.69–2.720.3681.990.89–4.430.0922.931.20–7.170.019
  Dominant model
    T/Tref.ref.ref.ref.
    T/TA+TA/TA1.300.84–2.020.2341.010.67–1.520.9731.380.83–2.310.2160.960.63–1.480.867
  Recessive model
    T/T+T/TAref.ref.ref.ref.
    TA/TA1.460.72–2.980.2921.420.74–2.730.2951.800.85–3.830.1273.321.39–7.910.007
HSD17B13 rs6531975
  Additive model
    G/Gref.ref.ref.ref.
    G/A0.690.44–1.080.1040.950.62–1.450.8020.940.56–1.600.8300.650.42–1.020.063
    A/A0.910.43–1.940.8090.590.28–1.240.1640.840.35–2.000.6900.480.24–0.980.043
  Dominant model
    G/Gref.ref.ref.ref.
    G/A+A/A0.730.48–1.110.1380.870.58–1.300.4960.920.56–1.520.7510.620.40–0.940.025
  Recessive model
    G/G+G/Aref.ref.ref.ref.
    A/A1.080.52–2.230.8330.600.29–1.240.1700.860.37–1.980.7260.590.30–1.160.123

HSD17B13 variants and hepatocyte ballooning and lobular inflammation

The proportion of severe ballooning in rs72613567 T/T, T/TA and TA/TA was 73 (36.9%), 58 (33.0%)and 21 (46.7%) respectively, while the proportion of severe ballooning in rs6531975 G/G, G/A and A/A was 79 (37.8%), 63 (37.1%) and 11 (26.8%) respectively. The proportion of severe inflammation in rs72613567 T/T, T/TA and TA/TA was 35 (17.7%), 35 (19.9%) and 12 (26.7%) respectively, while the proportion of severe inflammation in rs6531975 G/G, G/A and A/A was 40 (19.1%), 35 (20.6%) and 8 (19.5%) respectively (Table 3). Both severe ballooning and inflammation were unrelated to HSD17B13 variants in multivariate analysis (Table 4).

HSD17B13 variants and fibrosis

The prevalence of having fibrosis in rs72613567 T/T, T/TA and TA/TA was 135 (68.2%), 111 (63.1%) and 38 (84.4%) respectively. A higher prevalence of fibrosis was observed in patients with the TA/TA genotype in rs72613567 (p<0.05) (Table 3). In rs6531975 genotypes, the prevalence of having fibrosis in G/G, G/A and A/A was 150 (71.8%), 109 (64.1%) and 23 (56.1%) respectively. The A allele carriers of rs6531975 showed a nonsignificant trend for a reduced prevalence of having fibrosis (p=0.082) (Table 3).

To further understand the association between HSD17B13 variants and liver histology in Chinese patients with MAFLD, multivariate logistic regression modeling was undertaken. As shown in Table 4, rs72613567 TA/TA increased the risk of fibrosis with an odds ratio (OR) of 2.93 [TA/TA vs. T/T, 95% confidence interval (CI): 1.20–7.17, p=0.019] for the additive model and an OR of 3.32 (TA/TA vs. T/T+T/TA, 95% CI: 1.39–7.91, p=0.007) for the recessive model after adjusting for age, sex, BMI, presence of diabetes, fasting glucose, triglycerides and high-density lipoprotein cholesterol. In contrast, the rs6531975 A allele appeared to have a protective impact on fibrosis, with an OR of 0.48 (A/A vs. G/G, 95% CI: 0.24–0.98, p=0.043) for the additive model and an OR of 0.62 (G/A+A/A vs. G/G, 95% CI: 0.40–0.94, p=0.025) for the dominant model after adjusting for age, sex, BMI and presence of diabetes.

Interaction of PNPLA3 and HSD17B13 variants

Next, we conducted interaction analysis for HSD17B13 (rs72613567 and rs6531975) and PNPLA3 (rs738409) variants for their impact on liver histology. For fibrosis, no interaction effects were observed between the two genes. In contrast, there was an interaction between rs6531975 and rs738409 with regard to hepatic steatosis (Fig. 1). For the rs738409 risk allele carriers (CG+GG), the proportion of severe steatosis was lower in patients with the rs6531975 A allele (G/A+A/A) compared to those with rs6531975 G/G (Fig. 1A). Using the latter as reference, the rs6531975 A allele (G/A+A/A) attenuated the risk effect of the rs738409 G allele (C/G+G/G) on steatosis, with an OR of 0.57 (95% CI: 0.34–0.96, p=0.034) after adjusting for age, sex, BMI and presence of diabetes (Fig. 1B). The interaction between rs72613567 and rs738409 on liver steatosis was also performed (Fig. 2); however, no effect was observed.

Interaction of <italic>HSD17B13</italic> rs6531975 and <italic>PNPLA3</italic> rs738409 on liver steatosis.
Fig. 1  Interaction of HSD17B13 rs6531975 and PNPLA3 rs738409 on liver steatosis.

(A) Prevalence of mild steatosis and severe steatosis according to rs6531975 and rs738409 genotypes. (B) Interaction effect of rs6531975 and rs738409 on steatosis after adjusting for age, sex, BMI and presence of diabetes. Patients with the rs6531975 A allele (G/A+A/A) attenuated the risk effect of the rs738409 G allele (C/G+G/G) on steatosis, with an OR of 0.57 (95% CI: 0.34-0.96, p=0.034).

Interaction of <italic>HSD17B13</italic> rs72613567 and <italic>PNPLA3</italic> rs738409 on liver steatosis.
Fig. 2  Interaction of HSD17B13 rs72613567 and PNPLA3 rs738409 on liver steatosis.

(A) Prevalence of mild steatosis and severe steatosis according to rs72613567 and rs738409 genotypes. (B) Interaction effect of rs72613567 and rs738409 on steatosis after adjusting for age, sex, BMI and presence of diabetes. No interaction effect was observed between rs72613567 and rs738409.

Discussion

We characterized the impact of HSD17B13 gene variants on histological features in a cohort of Han Chinese with MAFLD. This study has three key findings. First, we confirmed the HSD17B13 region as a susceptibility locus for MAFLD-related fibrosis but extended these findings toward the identification of an inverse allelic direction of association as compared to that reported in Europeans. Second, the HSD17B13 variants are only associated with fibrosis and not any other histological feature. Third, the HSD17B13 variants modulate the effect of PNPLA3 rs738409 on hepatic steatosis but no other histological features.

The association between HSD17B13 variants and liver histological features seems to be complex, with multiple suggested functional variants. Notably, in our cohort, the minor allele TA of the rs72613567 variant was related to an increased risk of fibrosis, representing an inverse association as compared to the results in European cohorts. Hence, if there is a shared causal variant across European and Chinese populations, it is unlikely to be rs72613567. In this regard, we observed a protective effect in the minor A allele carriers of the HSD17B13 rs6531975 variant, but this is not in strong linkage disequilibrium with rs72613567. Thus, further fine-mapping studies in Han Chinese populations and comparison to other populations would be helpful to identify shared causal variants across different ethnicities.

The differential effect size and allele direction of variants discovered by GWAS between ethnicities is not uncommon. In one Chinese MAFLD cohort, researchers found that the neurocan (known as NCAN) rs2228603 T variant associated with a higher level of high-density lipoprotein,21 while it was positively related to liver steatosis in the USA population.22 Similarly, toll-like receptor 3 (known as TLR3) rs377529023,24 and interferon lambda-3 (known as IFNL3) rs1297986025,26 variants in Chinese hepatocellular carcinoma populations showed opposite effects to those in non-Asian populations. Inconsistent results have also been observed in other Asian populations, such as among Japanese. For example, tolloid-like 1 (known as TLL1) rs1704720027 and MHC class I polypeptide-related chain A (known as MICA) rs259654228 variants were suggested to have protective impacts on fibrosis and hepatocellular carcinoma in Caucasians. The associations were inverse to those of a Japanese cohort.29,30 Besides, there are several MAFLD-related SNPs in Europeans for which there has been no association in Chinese populations.31–33 Along the same line, lower genetic prediction accuracies (between 1.6-4.9-fold lower) were observed in other ethnicities compared to Europeans.8 Hence, increasing the representation of diverse populations and studying other ethnicities has recently become a research priority to enhance understanding of the human genetic architecture and its translational implications.

The ethnic differences in the characteristics of patients with MAFLD might also contribute to the observed differences in the genetic findings. There is growing evidence, for example, that the MAFLD disease course in Asian populations is different to that in Caucasians. As an example, for the same BMI, there is a higher prevalence of MAFLD in Asians. Published reports also indicate that lean MAFLD accounts for 36.9% of cases in China,3 but only 17.3% of the total disease burden in the USA.34 Differences in metabolic adaptation have been reported between lean and non-lean MAFLD patients, suggesting that lean fatty liver disease likely has a distinct pathophysiology.35

Another intriguing aspect of this study is the lack of association found between HSD17B13 variants and other histological features. To date, the nature of the association between the rs72613567 allelic variant and the histological features of MAFLD, particularly steatosis, is unclear. Abul-Husn and colleagues10 suggested a lack of association between the rs72613567 TA variant and steatosis in human liver, consistent with the study of Pirola et al.11 However, a study by Ma et al.9 found a significant association with hepatic steatosis. Similarly, in animal and in vitro studies, inconsistent results have been reported for an effect of HSD17B13 on hepatic lipid accumulation. Abul-Husn et al.10 showed no differences in lipid accumulation according HSD17B13 isoforms. Similarly Ma et al.9 reported that HSD17B13 overexpression or knockout in HepG2 cells did not affect lipid content. On the other hand, Marion et al.36 noted hepatic steatosis in HSD17B13 knockout mice, whilst Su et al.37 observed steatosis in mice that overexpressed HSD17B13. Collectively, these results imply that HSD17B13 variants could have a direct impact on fibrosis rather than effects on steatosis. These findings may be associated with retinol metabolism, since retinol plays a crucial role in the activation and transformation of hepatic stellate cells to matrix secreting myofibroblasts and the development of hepatic fibrosis.38 Since HSD17B13 participates in the rate limiting step of retinol metabolism,9 the mutant in HSD17B13 might conceivably influence the process of fibrosis.

The interaction between HSD17B13 and PNPLA3 variants in MAFLD is also a subject of controversy.14,39 In this work, we noted an interaction between these variants with regard to steatosis, but not with other histological features. As HSD17B13 has been suggested as a potential therapeutic target for MAFLD and considering the growing concerns about the failure of phase 2 and 3 clinical trials in this disease40,41 that was at least partially attributed to clinical heterogeneity, our study highlights the importance of first understanding the functional basis of the various proposed genomic and other targets before therapeutic development.40,42 Collectively, our data support such an approach. The data from HSD17B13-knockout mice, in fact, suggest that HSD17B13 triggers steatosis and inflammation,36 which is opposite to what has been reported in humans.

The present study has limitations. First, the sample size is modest. In case the observed opposite finding is due to the sample size, we performed a post-hoc power analysis. The power calculated for the model was 72%. It is close to but less than 80%. Considering the low proportion of the rs72613567 TA variant in the general population, we think it is acceptable. In addition, lack of a validation cohort from populations in other parts of China or those of Chinese ancestry living outside mainland China is another limitation.

In conclusion, the HSD17B13 rs72613567 variant appears to be a risk variant for hepatic fibrosis in a Han Chinese MAFLD population, with a different direction for allelic association to that seen in Europeans.

Supporting information

Supplementary Table 1

Baseline characteristics of biopsy-confirmed Chinese MAFLD patients.

(DOCX)

Abbreviations

BMI: 

body mass index

CI: 

confidence interval

GWAS: 

genome-wide association studies

HOMA: 

homoeostasis model assessment

HSD17B13

hydroxysteroid 17-beta dehydrogenase 13

IFNL3: 

interferon lambda-3

IR: 

insulin resistance

MAF: 

minor allele frequency

MAFL: 

metabolic-associated fatty liver

MAFLD: 

metabolic-associated fatty liver disease

MICA

MHC class I polypeptide-related chain A

NCAN

neurocan

OR: 

odds ratio

PNPLA3

patatin-like phospholipase domain containing protein 3

SNP: 

single nucleotide polymorphism

TLL1: 

tolloid-like 1

TLR3: 

toll-like receptor 3

Declarations

Funding

This work was supported by grants from the National Natural Science Foundation of China (82070588), High Level Creative Talents from Department of Public Health in Zhejiang Province (S2032102600032) and Project of New Century 551 Talent Nurturing in Wenzhou. GT was supported in part by grants from the University School of Medicine of Verona (Verona, Italy). CDB was supported in part by the Southampton NIHR Biomedical Research Centre (IS-BRC-20004), UK. ME and JG were supported by the Robert W. Storr Bequest to the Sydney Medical Foundation, University of Sydney (Sydney, Australia) and the National Health and Medical Research Council of Australia (NHMRC) Program (APP1053206, APP1149976) and Project (APP1107178 and APP1108422) grants.

Conflict of interest

The authors have no conflict of interests related to this publication.

Authors’ contributions

Study concept and design (WYL, ME, JG, MHZ), acquisition of data (HLM, LJT, GL, PWZ), pathology analysis (XDW), drafting of the manuscript (WYL, ME, JG, KIZ, RSR), critical revision of the manuscript (ME, JG, GT, CDB), statistical analysis (WYL, ME, MZL), study supervision (JG, MHZ), guarantor of the article (MHZ).

References

  1. EASL-EASD-EASO Clinical Practice Guidelines for the management of non-alcoholic fatty liver disease. J Hepatol 2016;64:1388-1402 View Article PubMed/NCBI
  2. Younossi ZM, Koenig AB, Abdelatif D, Fazel Y, Henry L, Wymer M. Global epidemiology of nonalcoholic fatty liver disease-Meta-analytic assessment of prevalence, incidence, and outcomes. Hepatology 2016;64:73-84 View Article PubMed/NCBI
  3. Zhou F, Zhou J, Wang W, Zhang XJ, Ji YX, Zhang P, et al. Unexpected rapid increase in the burden of NAFLD in China from 2008 to 2018: A systematic review and meta-analysis. Hepatology 2019;70:1119-1133 View Article PubMed/NCBI
  4. Masuoka HC, Chalasani N. Nonalcoholic fatty liver disease: an emerging threat to obese and diabetic individuals. Ann N Y Acad Sci 2013;1281:106-122 View Article PubMed/NCBI
  5. Buzzetti E, Pinzani M, Tsochatzis EA. The multiple-hit pathogenesis of non-alcoholic fatty liver disease (NAFLD). Metabolism 2016;65:1038-1048 View Article PubMed/NCBI
  6. Eslam M, George J. Genetic contributions to NAFLD: leveraging shared genetics to uncover systems biology. Nat Rev Gastroenterol Hepatol 2020;17:40-52 View Article PubMed/NCBI
  7. Eslam M, Valenti L, Romeo S. Genetics and epigenetics of NAFLD and NASH: Clinical impact. J Hepatol 2018;68:268-279 View Article PubMed/NCBI
  8. Martin AR, Kanai M, Kamatani Y, Okada Y, Neale BM, Daly MJ. Clinical use of current polygenic risk scores may exacerbate health disparities. Nat Genet 2019;51:584-591 View Article PubMed/NCBI
  9. Ma Y, Belyaeva OV, Brown PM, Fujita K, Valles K, Karki S, et al. 17-Beta hydroxysteroid dehydrogenase 13 is a hepatic retinol dehydrogenase associated with histological features of nonalcoholic fatty liver disease. Hepatology 2019;69:1504-1519 View Article PubMed/NCBI
  10. Abul-Husn NS, Cheng X, Li AH, Xin Y, Schurmann C, Stevis P, et al. A protein-truncating HSD17B13 variant and protection from chronic liver disease. N Engl J Med 2018;378:1096-1106 View Article PubMed/NCBI
  11. Pirola CJ, Garaycoechea M, Flichman D, Arrese M, San Martino J, Gazzi C, et al. Splice variant rs72613567 prevents worst histologic outcomes in patients with nonalcoholic fatty liver disease. J Lipid Res 2019;60:176-185 View Article PubMed/NCBI
  12. Scheiner B, Stättermayer AF, Schwabl P, Bucsics T, Paternostro R, Bauer D, et al. Impact of HSD17B13 rs72613567 genotype on hepatic decompensation and mortality in patients with portal hypertension. Liver Int 2020;40:393-404 View Article PubMed/NCBI
  13. Kallwitz E, Tayo BO, Kuniholm MH, Daviglus M, Zeng D, Isasi CR, et al. Association of HSD17B13 rs72613567:TA with non-alcoholic fatty liver disease in Hispanics/Latinos. Liver Int 2020;40:889-893 View Article PubMed/NCBI
  14. Stickel F, Lutz P, Buch S, Nischalke HD, Silva I, Rausch V, et al. Genetic variation in HSD17B13 reduces the risk of developing cirrhosis and hepatocellular carcinoma in alcohol misusers. Hepatology 2020;72:88-102 View Article PubMed/NCBI
  15. Eslam M, Newsome PN, Sarin SK, Anstee QM, Targher G, Romero-Gomez M, et al. A new definition for metabolic dysfunction-associated fatty liver disease: An international expert consensus statement. J Hepatol 2020;73:202-209 View Article PubMed/NCBI
  16. Liu WY, Zheng KI, Pan XY, Ma HL, Zhu PW, Wu XX, et al. Effect of PNPLA3 polymorphism on diagnostic performance of various noninvasive markers for diagnosing and staging nonalcoholic fatty liver disease. J Gastroenterol Hepatol 2020;35:1057-1064 View Article PubMed/NCBI
  17. Matthews DR, Hosker JP, Rudenski AS, Naylor BA, Treacher DF, Turner RC. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia 1985;28:412-419 View Article PubMed/NCBI
  18. American Diabetes Association. Improving care and promoting health in populations: Standards of Medical Care in Diabetes-2020. Diabetes Care 2020;43:S7-S13 View Article PubMed/NCBI
  19. Kleiner DE, Brunt EM, Van Natta M, Behling C, Contos MJ, Cummings OW, et al. Design and validation of a histological scoring system for nonalcoholic fatty liver disease. Hepatology 2005;41:1313-1321 View Article PubMed/NCBI
  20. Auton A, Brooks LD, Durbin RM, Garrison EP, Kang HM, Korbel JO, et al. A global reference for human genetic variation. Nature 2015;526:68-74 View Article PubMed/NCBI
  21. Wu MJ, Yuan C, Lu LL, An BQ, Xuan SY, Xin YN. Role of NCAN rs2228603 polymorphism in the incidence of nonalcoholic fatty liver disease: a case-control study. Lipids Health Dis 2016;15:207 View Article PubMed/NCBI
  22. Hernaez R, McLean J, Lazo M, Brancati FL, Hirschhorn JN, Borecki IB, et al. Association between variants in or near PNPLA3, GCKR, and PPP1R3B with ultrasound-defined steatosis based on data from the third National Health and Nutrition Examination Survey. Clin Gastroenterol Hepatol 2013;11:1183-1190.e2 View Article PubMed/NCBI
  23. Huang X, Li H, Wang J, Huang C, Lu Y, Qin X, et al. Genetic polymorphisms in Toll-like receptor 3 gene are associated with the risk of hepatitis B virus-related liver diseases in a Chinese population. Gene 2015;569:218-224 View Article PubMed/NCBI
  24. Sghaier I, Zidi S, Mouelhi L, Ghazoueni E, Brochot E, Almawi WY, et al. TLR3 and TLR4 SNP variants in the liver disease resulting from hepatitis B virus and hepatitis C virus infection. Br J Biomed Sci 2019;76:35-41 View Article PubMed/NCBI
  25. Hou W, Qiao K, Huo Z, Du Y, Wang C, Syn WK. Association of IFNL3 rs12979860 polymorphism with HCV-related hepatocellular carcinoma susceptibility in a Chinese population. Clin Exp Gastroenterol 2019;12:433-439 View Article PubMed/NCBI
  26. Buivydiene A, Liakina V, Kashuba E, Norkuniene J, Jokubauskiene S, Gineikiene E, et al. Impact of the uridine-cytidine kinase like-1 protein and IL28B rs12979860 and rs8099917 SNPs on the development of hepatocellular carcinoma in cirrhotic chronic hepatitis C patients-A pilot study. Medicina (Kaunas) 2018;54:67 View Article PubMed/NCBI
  27. John M, Metwally M, Mangia A, Romero-Gomez M, Berg T, Sheridan D, et al. TLL1 rs17047200 increases the risk of fibrosis progression in caucasian patients with chronic hepatitis C. Gastroenterology. 2017;153:1448-1449 View Article PubMed/NCBI
  28. Lange CM, Bibert S, Dufour JF, Cellerai C, Cerny A, Heim MH, et al. Comparative genetic analyses point to HCP5 as susceptibility locus for HCV-associated hepatocellular carcinoma. J Hepatol 2013;59:504-509 View Article PubMed/NCBI
  29. Kumar V, Kato N, Urabe Y, Takahashi A, Muroyama R, Hosono N, et al. Genome-wide association study identifies a susceptibility locus for HCV-induced hepatocellular carcinoma. Nat Genet 2011;43:455-458 View Article PubMed/NCBI
  30. Matsuura K, Sawai H, Ikeo K, Ogawa S, Iio E, Isogawa M, et al. Genome-wide association study identifies TLL1 variant associated with development of hepatocellular carcinoma after eradication of hepatitis C virus infection. Gastroenterology 2017;152:1383-1394 View Article PubMed/NCBI
  31. Yuan C, Lu L, An B, Jin W, Dong Q, Xin Y, et al. Association between LYPLAL1 rs12137855 polymorphism with ultrasound-defined non-alcoholic fatty liver disease in a Chinese Han population. Hepat Mon 2015;15:e33155 View Article PubMed/NCBI
  32. Peng XE, Chen FL, Liu W, Hu Z, Lin X. Lack of association between SREBF-1c gene polymorphisms and risk of non-alcoholic fatty liver disease in a Chinese Han population. Sci Rep 2016;6:32110 View Article PubMed/NCBI
  33. Niu TH, Jiang M, Xin YN, Jiang XJ, Lin ZH, Xuan SY. Lack of association between apolipoprotein C3 gene polymorphisms and risk of nonalcoholic fatty liver disease in a Chinese Han population. World J Gastroenterol 2014;20:3655-3662 View Article PubMed/NCBI
  34. Younossi ZM, Stepanova M, Negro F, Hallaji S, Younossi Y, Lam B, et al. Nonalcoholic fatty liver disease in lean individuals in the United States. Medicine (Baltimore) 2012;91:319-327 View Article PubMed/NCBI
  35. Chen F, Esmaili S, Rogers GB, Bugianesi E, Petta S, Marchesini G, et al. Lean NAFLD: A distinct entity shaped by differential metabolic adaptation. Hepatology 2020;71:1213-1227 View Article PubMed/NCBI
  36. Adam M, Heikelä H, Sobolewski C, Portius D, Mäki-Jouppila J, Mehmood A, et al. Hydroxysteroid (17β) dehydrogenase 13 deficiency triggers hepatic steatosis and inflammation in mice. FASEB J 2018;32:3434-3447 View Article PubMed/NCBI
  37. Su W, Wang Y, Jia X, Wu W, Li L, Tian X, et al. Comparative proteomic study reveals 17β-HSD13 as a pathogenic protein in nonalcoholic fatty liver disease. Proc Natl Acad Sci U S A 2014;111:11437-11442 View Article PubMed/NCBI
  38. Puche JE, Saiman Y, Friedman SL. Hepatic stellate cells and liver fibrosis. Compr Physiol 2013;3:1473-1492 View Article PubMed/NCBI
  39. Bellan M, Colletta C, Barbaglia MN, Salmi L, Clerici R, Mallela VR, et al. Severity of nonalcoholic fatty liver disease in type 2 diabetes mellitus: Relationship between nongenetic factors and PNPLA3/HSD17B13 polymorphisms. Diabetes Metab J 2019;43:700-710 View Article PubMed/NCBI
  40. Ratziu V, Friedman SL. Why do so many NASH trials fail?. Gastroenterology 2020 View Article PubMed/NCBI
  41. Eslam M, George J. Genetic insights for drug development in NAFLD. Trends Pharmacol Sci 2019;40:506-516 View Article PubMed/NCBI
  42. Eslam M, Sanyal AJ, George J. MAFLD: A consensus-driven proposed nomenclature for metabolic associated fatty liver disease. Gastroenterology 2020;158:1999-2014.e1 View Article PubMed/NCBI