TM6SF2 Gene Variant Increases Liver Disease Risk While Lowering Circulating Lipids

A large-scale systematic review and meta-analysis of observational studies has revealed that the rs58542926 variant in the transmembrane 6 superfamily member 2 gene significantly increases susceptibility to metabolic dysfunction-associated steatotic liver disease in adults while simultaneously conferring a paradoxically favorable peripheral lipid profile. Investigators pooling data from fifty-five observational studies comprising 368,852 adult participants found that carriers of the variant allele faced a forty percent higher likelihood of developing metabolic dysfunction-associated steatotic liver disease compared with non-carriers under a dominant genetic inheritance model. Furthermore, the genetic variant demonstrated consistent links to more pronounced hepatic steatosis and significant fibrosis, highlighting its direct influence on structural liver pathology. Despite these detrimental manifestations within liver tissue, individuals possessing the variant exhibited notably lower circulating concentrations of triglycerides, total cholesterol, and low-density lipoprotein cholesterol. These rigorous findings establish that the genetic alteration uncouples hepatic fat accumulation from typical systemic dyslipidemia, defining a genetically distinctive subtype of chronic liver disease that cannot be reliably captured through conventional circulating blood lipid panels alone.

Metabolic dysfunction-associated steatotic liver disease has emerged as one of the most widespread chronic liver conditions globally, with epidemiological records documenting an increase in worldwide prevalence from roughly twenty-two percent in 1990 to thirty-eight percent in recent years. As an updated international consensus transitioned the diagnostic definition from non-alcoholic fatty liver disease to metabolic dysfunction-associated steatotic liver disease, expert guidance placed greater emphasis on systemic cardiometabolic abnormalities while acknowledging substantial clinical, metabolic, and genetic heterogeneity. The clinical trajectory of the disease encompasses progressive hepatic injuries, ranging from simple intrahepatic lipid deposition to advanced fibrosis, cirrhosis, and hepatocellular carcinoma, alongside heightened risks of cardiovascular complications and all-cause mortality. Emerging research indicates that pathogenesis arises from complex interplays between environmental exposures and inherited genetic predispositions, with chronic inflammation, insulin resistance, and disrupted lipid handling operating at the center of disease progression. Among identified genetic determinants, the rs58542926 cytosine-to-thymine substitution alters the transmembrane 6 superfamily member 2 protein through an E167K functional mutation that impairs hepatic very-low-density lipoprotein export and promotes excessive fat retention.

To clarify previously discordant findings regarding genetic susceptibility, histological endpoints, and prognostic outcomes across disparate patient populations, researchers registered a formal systematic review protocol with the international prospective register of systematic reviews under identification CRD420251273179. The investigation strictly complied with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement, the Meta-analysis of Observational Studies in Epidemiology guidelines, and established reporting standards for genetic association studies. Reviewers carried out an extensive literature retrieval across PubMed, Embase, Web of Science, and the Cochrane Library for observational reports published from database inception through 11 November 2025, without imposing restrictions on participant sex, ethnic heritage, or geographic location. Eligible studies specifically enrolled adult participants aged eighteen years or older, reported clear genotype or allele frequency statistics for the rs58542926 polymorphism, and provided quantifiable evaluation of disease susceptibility, histological changes, clinical metabolic parameters, or longitudinal clinical endpoints. Studies examining steatotic liver diseases secondary to identifiable external causes such as viral hepatitis, drug toxicity, or autoimmune etiologies were systematically excluded to maintain strict disease specificity.

The initial comprehensive database interrogation identified 1,632 published records, from which 587 duplicate entries were removed and 626 articles were excluded during title and abstract screening, leaving 419 publications for full-text eligibility appraisal. Ultimately, fifty-five observational investigations met all pre-established selection criteria and were incorporated into the quantitative synthesis. Geographic distribution showed strong representation from Asia with twenty-two studies and Europe with twenty-one studies, complemented by six investigations from North America, five from South America, and single studies originating from Africa and Oceania. Within the twenty-six studies specifically examining disease susceptibility, data were synthesized from 12,211 patients diagnosed with metabolic dysfunction-associated steatotic liver disease, representing a collective cohort where female participants comprised 44.5 percent, the mean participant age was 58.9 years, and the mean body mass index reached 29.01 kilograms per square meter. In addition, roughly 19.7 percent of evaluated patients presented with concurrent type 2 diabetes mellitus, while genotype distributions among all control groups conformed to expected Hardy-Weinberg equilibrium benchmarks.

Quantitative pooling across twenty-six studies evaluating disease susceptibility demonstrated that the rs58542926 thymine allele was significantly associated with heightened risk under a dominant genetic model, yielding an odds ratio of 1.40 with a 95 percent confidence interval spanning from 1.27 to 1.55. Subgroup analyses stratified by diagnostic modality confirmed that the genetic association remained highly robust and statistically significant in cohorts evaluated through direct imaging or histological methodologies, including conventional ultrasound, percutaneous liver biopsy, and transient elastography with controlled attenuation parameters. Conversely, cohorts defined through circulating metabolic biomarker indices or mixed diagnostic criteria failed to demonstrate statistically significant associations, registering probability values of 0.09 and 0.12, respectively. Stratification by geographic origin revealed significant regional differences, characterized by pronounced associations across Asian and European populations, whereas cohorts from South America, Africa, and Oceania showed no statistically significant relationship. Interestingly, the synthesized evidence indicated that the variant was not significantly associated with progression from simple steatosis to metabolic dysfunction-associated steatohepatitis, reflecting a potential probability value of 0.37.

Detailed evaluation of hepatic histological features substantiated the direct influence of the thymine allele on intrahepatic structural pathology among patients diagnosed with metabolic dysfunction-associated steatotic liver disease. Synthesis of six studies encompassing 2,832 adult patients indicated that carriers of the thymine allele faced a significantly heightened probability of developing moderate-to-severe hepatic steatosis, producing an odds ratio of 1.42 with a 95 percent confidence interval between 1.11 and 1.80. Moreover, histological evaluation across thirteen investigations involving 7,021 patients demonstrated a significant association with significant liver fibrosis, defined as stages F2 through F4, yielding a pooled odds ratio of 1.34 with a 95 percent confidence interval ranging from 1.07 to 1.68. However, pooled statistical estimates showed no significant relationship with the broader presence of any histological fibrosis, contrasting stage F0 against stages F1 through F4, nor with advanced fibrosis, contrasting stages F0 through F2 against stages F3 through F4, suggesting that genetic effects may specifically accelerate intermediate structural fibrogenesis rather than uniformly driving terminal stages.

Analysis of circulating metabolic parameters demonstrated a striking dissociation between hepatic fat accumulation and peripheral lipid profiles among carriers of the rs58542926 variant. The thymine allele was consistently associated with a favorable circulating lipid architecture, characterized by significant reductions in serum triglycerides, total cholesterol, and low-density lipoprotein cholesterol, alongside a slight but statistically significant elevation in high-density lipoprotein cholesterol. The greatest quantitative reduction occurred in circulating triglyceride concentrations, which exhibited a pooled mean difference of minus 14.64 milligrams per deciliter, bounded by a 95 percent confidence interval of minus 19.12 to minus 10.16 milligrams per deciliter. Concurrently, pooled evaluations established that the genetic variant exhibited no significant correlation with general adiposity as measured by body mass index, yielding a non-significant probability value of 0.56. Mechanistically, this distinctive dissociation is directly explained by impaired hepatic export of very-low-density lipoproteins and apolipoprotein B100, which traps lipids within the liver parenchyma while lowering circulating atherogenic lipoprotein fractions in the bloodstream.

Expanding beyond standard lipid profiling, the meta-analysis synthesized data on circulating glucose metabolism parameters and biochemical markers of hepatocellular injury. Carriers of the thymine allele displayed modest but statistically significant elevations in fasting blood glucose and fasting insulin concentrations, whereas other systemic measures, including homeostatic model assessment of insulin resistance, random plasma glucose, and glycated hemoglobin, exhibited no significant alterations across pooled cohorts. Sensitivity analyses excluding potential outliers yielded consistent results for fasting blood glucose, demonstrating a persistent mean difference of 0.91 milligrams per deciliter. Regarding circulating hepatic enzymes, variant carriers demonstrated modestly elevated circulating levels of aspartate aminotransferase and alanine aminotransferase, alongside significantly lower alkaline phosphatase levels and unchanged gamma-glutamyltransferase measurements. Although statistically significant, the pooled absolute differences for aspartate aminotransferase and alanine aminotransferase remained relatively minor at 1.69 units per liter and 1.34 units per liter, respectively, suggesting that isolated enzyme increments possess limited standalone diagnostic sensitivity in clinical practice.

The investigation also compiled longitudinal outcome data, offering preliminary insights into the long-term clinical prognosis associated with the transmembrane 6 superfamily member 2 variant. Under a standard dominant genetic model, random-effects pooling across four studies comprising 162,793 participants revealed a potential association with an increased incidence of liver-related clinical events, exhibiting a hazard ratio of 2.20 with a 95 percent confidence interval of 1.22 to 3.95. However, this statistical significance was attenuated following rigorous Hartung-Knapp-Sidik-Jonkman adjustment, producing a broader 95 percent confidence interval from 0.79 to 6.12 and a probability value of 0.092. Furthermore, leave-one-out sensitivity evaluations demonstrated that individual cohort datasets substantially shifted effect magnitudes, underscoring notable analytical fragility. In contrast, examining heterozygous carriers versus wild-type homozygotes within a single observational study revealed a significant association with reduced cardiovascular mortality, registering a hazard ratio of 0.35 with a 95 percent confidence interval from 0.13 to 0.97, while overall mortality, cirrhosis, and cardiovascular disease incidences showed no significant associations across examined models.

The investigators noted several essential methodological limitations that require measured interpretation of the findings when contemplating clinical translation. Because all included investigations relied on observational designs, unmeasured residual confounding cannot be entirely eliminated, and many included historical studies predated the contemporary definition of metabolic dysfunction-associated steatotic liver disease, creating potential diagnostic misclassification across cohorts. Furthermore, the limited number of studies evaluating longitudinal endpoints, high statistical heterogeneity in liver-related event analyses, and the absence of multiple-testing corrections across secondary parameters represent critical caveats. The primary literature also lacked consistent documentation regarding patient nutritional habits, alcohol intake, pharmaceutical regimens, glycemic control, and broader polygenic architecture. Consequently, while the variant serves as a compelling supplementary marker for identifying individuals who harbor severe liver fat accumulation and advanced fibrosis despite seemingly benign lipid profiles, researchers emphasized that incorporating this genetic locus into risk stratification models alongside existing scoring algorithms requires further prospective validation before routine clinical deployment can be recommended.

Subject of Research: Association of TM6SF2 rs58542926 with metabolic dysfunction-associated steatotic liver disease and clinical outcomes

Article Title: Association of TM6SF2 rs58542926 with MASLD, clinical phenotypes, and longitudinal outcomes: a systematic review and meta-analysis

Article References: Zhou, X., Liu, Z., Mao, R., Xu, T., & Lin, Z. (2026). Association of TM6SF2 rs58542926 with MASLD, clinical phenotypes, and longitudinal outcomes: a systematic review and meta-analysis. Frontiers in Genetics, 17, Article 1934336. https://doi.org/10.3389/fgene.2026.1934336

Image Credits: AI Generated

DOI: 10.3389/fgene.2026.1934336

Keywords: TM6SF2, rs58542926, MASLD, metabolic dysfunction-associated steatotic liver disease, hepatic steatosis, liver fibrosis, lipid metabolism, triglycerides, cholesterol, genetic epidemiology, meta-analysis, systematic review, liver injury markers, alanine aminotransferase, aspartate aminotransferase, liver-related events, cardiovascular mortality