HSD17B13
HSD17B13 is a lipid droplet-associated enzyme that acts as a powerful genetic shield against progressive liver disease. A common loss-of-function variant significantly reduces the risk of cirrhosis and liver cancer, even in the presence of fatty liver.
Key Takeaways
- •HSD17B13 is a liver-specific enzyme that resides on the surface of lipid droplets.
- •The "TA" insertion variant (rs72613567) is a loss-of-function mutation that is highly protective against liver fibrosis.
- •Carriers of the protective variant are ~30-50% less likely to develop alcoholic or non-alcoholic cirrhosis.
- •HSD17B13 highlights a rare therapeutic opportunity: mimicking a genetic loss-of-function to treat chronic disease.
Basic Information
- Gene Symbol
- HSD17B13
- Full Name
- Hydroxysteroid 17-Beta Dehydrogenase 13
- Also Known As
- HSD17B11SDR16C1
- Location
- 4q22.1
- Protein Type
- Hepatic Lipid Droplet Enzyme
- Protein Family
- Short-chain dehydrogenase/reductase
Related Isoforms
Key SNPs
The "TA" insertion; causes a loss of protein function and provides significant protection against liver fibrosis.
Encodes P260S; a frequent missense variant often studied for its cumulative effect on liver enzyme levels.
A regulatory marker associated with HSD17B13 expression levels in the liver.
Overview
HSD17B13 (Hydroxysteroid 17-Beta Dehydrogenase 13) is a member of the short-chain dehydrogenase/reductase family, specifically localized to the surface of lipid droplets in hepatocytes. While its exact enzymatic substrate in vivo is still being debated, it appears to play a critical role in remodeling the lipid and phospholipid composition of the droplet membrane.
Unlike many liver-related genes where mutations *cause* disease (like PNPLA3), HSD17B13 is famous for a mutation that *prevents* disease. A common "splice-site" variant results in a truncated, non-functional protein. Individuals who lack functional HSD17B13 are profoundly protected from the inflammatory transition from simple "fatty liver" to the destructive scarring of cirrhosis and liver cancer.
Conceptual Model
A simplified mental model for the pathway:
Losing the "gatekeeper" (HSD17B13) paradoxically prevents the liver from "tripping" the fibrosis alarm.
Core Health Impacts
- • Fibrosis Protection: Significantly reduces the risk of transition from steatosis to cirrhosis
- • Enzyme Stabilization: Lowers baseline and injury-induced ALT/AST liver enzyme levels
- • Cancer Prevention: Decreases the risk of Hepatocellular Carcinoma (HCC) in high-risk patients
- • Lipid Remodeling: Influences the phospholipid and retinol composition of liver fat droplets
- • Alcohol Resilience: Attenuates the liver-damaging effects of chronic alcohol consumption
Protein Domains
SDR Catalytic Domain
Contains the characteristic Rossmann fold and catalytic triad (Ser-Tyr-Lys) used for steroid or lipid metabolism.
Lipid Droplet Anchor
Highly hydrophobic N-terminal sequences that allow the protein to insert specifically into the phospholipid monolayer of fat droplets.
Upstream Regulators
Estrogen Modulator
Hormonal regulator that can modulate HSD17B13 expression; may contribute to sex differences in liver disease.
Liver Injury Activator
The gene is upregulated in response to chronic inflammation and steatosis, potentially as part of a maladaptive response.
Nutritional Overload Activator
High-fat and high-sugar diets increase the recruitment of HSD17B13 to expanding lipid droplets.
Downstream Targets
Lipid Droplet Size Activates
HSD17B13 activity influences the dynamics of how fat droplets grow and merge within the cell.
Phospholipids Activates
The enzyme modulates the ratio of phosphatidylcholine to phosphatidylethanolamine on the droplet surface.
Retinyl Esters Activates
Interacts with the metabolism of Vitamin A stores within the liver, impacting stellate cell activation.
Hepatic Inflammation Activates
The functional protein promotes the pro-inflammatory environment required for MASH progression.
Fibrosis Progression Activates
The presence of the protein is required for the full activation of the liver's scarring machinery.
Role in Aging
HSD17B13 is a "longevity gene" for the liver. By slowing the rate of fibrosis progression, it preserves the functional reserve of the liver across the human lifespan, particularly in the face of modern metabolic stressors.
Extended Liver Span
Carriers of the protective variant maintain "younger" liver architecture for longer, avoiding the late-life transition to cirrhosis.
Resilience to Insult
HSD17B13 loss-of-function provides a biological "buffer" against the age-related accumulation of metabolic and toxic (alcohol) damage.
Stellate Cell Quiescence
By modulating lipid droplet signaling, the protective variant helps keep hepatic stellate cells in a "quiet," non-fibrogenic state as they age.
HCC Delay
The protective effect extends to liver cancer, significantly pushing back the age at which HCC typically emerges in high-risk populations.
Metabolic Flexibility
Alterations in lipid droplet remodeling in carriers may support better hepatic metabolic flexibility during the aging process.
Inflammaging Mitigation
Reducing the liver's inflammatory "output" (MASH) contributes to a lower overall systemic inflammaging burden.
Disorders & Diseases
MASH (Steatohepatitis)
The presence of functional HSD17B13 is a requirement for the progression from simple fat (steatosis) to active inflammation and cell death (MASH).
Liver Cirrhosis
The "TA" variant is the strongest known genetic protector against cirrhosis, providing protection across alcoholic, non-alcoholic, and viral etiologies.
Hepatocellular Carcinoma
By blocking the "fibrosis-to-cancer" sequence, HSD17B13 loss-of-function provides a significant reduction in liver cancer risk.
Alcohol-Related Liver Disease
Carriers of the protective variant are significantly less likely to develop severe liver damage from chronic alcohol use.
The PNPLA3 Counter-balance
HSD17B13 protection is so strong that it can "cancel out" much of the increased risk conferred by the PNPLA3 I148M variant.
Interventions
Supplements
Additive protection; coffee consumption and HSD17B13 protection independently reduce the risk of advanced liver disease.
May support liver health in MASH patients, though the effect is independent of HSD17B13 genotype.
Help manage liver fat levels, which is the baseline "fuel" that HSD17B13 uses to drive inflammation.
Studied for its role in glutathione production and liver protection during oxidative stress.
Lifestyle
While carriers are protected, avoiding excess alcohol remains the most important lifestyle factor for liver longevity.
Reduces the de novo fat synthesis that leads to the steatosis required for HSD17B13-mediated injury.
Losing weight reduces the "steatosis burden," making the HSD17B13 protective effect even more clinically significant.
High-risk patients (especially PNPLA3 carriers) should know their HSD17B13 status to better understand their risk of progression.
Medicines
The "Holy Grail" of MASLD drug development; several companies are developing RNA therapies to mimic the protective mutation.
An RNA interference therapy currently in clinical trials designed to silence HSD17B13 in the liver.
Provide systemic metabolic benefits that complement the local liver protection of HSD17B13 variants.
Help reduce the underlying steatosis that HSD17B13-mediated inflammation acts upon.
Lab Tests & Biomarkers
Genetic Testing
The definitive test for the protective "TA" insertion. Highly recommended for patients with MASLD or alcohol risk.
Assesses the balance between injury genes (PNPLA3, TM6SF2) and the protective HSD17B13 gene.
Liver Enzymes
Typically lower in carriers of the HSD17B13 protective variant, even if liver fat is present.
A marker of bile duct health and alcohol-related liver stress, often improved in protected carriers.
Fibrosis Markers
Used to confirm that carriers have less liver stiffness (scarring) than expected for their level of fat.
A non-invasive score using age and blood markers; typically lower in HSD17B13-protected individuals.
Hormonal Interactions
Estrogen Modulator
May interact with HSD17B13 to provide superior liver protection in premenopausal women.
Thyroid Hormone (T3) Regulator
Influences the rate of lipid droplet turnover, which is the substrate for HSD17B13 activity.
Insulin Driver
Drives the recruitment of HSD17B13 to lipid droplets by increasing de novo lipogenesis.
Glucocorticoids Regulator
Can influence the hepatic inflammatory tone that HSD17B13 helps to mediate.
Deep Dive
Network Diagrams
HSD17B13: The Protective Logic
The Lipid Droplet Shield: HSD17B13 and Fibrosis
To understand HSD17B13, one must look closely at the “fat bubbles” (lipid droplets) inside a liver cell. These are not just passive storage units; they are dynamic organelles covered in enzymes that communicate with the rest of the cell.
The Functional Protein: Functional HSD17B13 is a “pro-fibrotic” enzyme. While its exact natural substrate is still a topic of intense research, its presence on the lipid droplet appears to signal the cell to initiate an inflammatory response when fat levels are high.
The TA Variant (The Shield): The protective rs72613567 variant is an insertion of two bases (TA) at a critical splice site. This causes the cell to produce a “broken” version of the enzyme. Without functional HSD17B13, the fat droplet fails to send the “danger signals” that would normally trigger inflammation and scarring.
The Yin and Yang: Interaction with PNPLA3
The most significant clinical insight regarding HSD17B13 is its relationship with PNPLA3, the strongest risk factor for fatty liver.
The Risk Carrier: A patient with the PNPLA3 I148M variant has a high risk of trapping fat in the liver and progressing to cirrhosis.
The Rescue: If that same patient also carries the HSD17B13 protective variant, their risk of cirrhosis is slashed by nearly 50%. The protection of HSD17B13 is powerful enough to “cancel out” much of the damage driven by PNPLA3. This explains the “benign steatosis” phenotype—individuals with very fatty livers who never develop liver failure.
Mimicking Genetics: A New Class of Drugs
The discovery of HSD17B13 has triggered a gold rush in the pharmaceutical industry. Most drugs try to increase the activity of a helpful pathway or replace a missing function. HSD17B13 offers a different strategy: mimicking a beneficial loss-of-function.
Gene Silencing: Because individuals born without functional HSD17B13 are perfectly healthy (they only have better liver outcomes), it is a safe target for “silencing.” RNA interference (siRNA) and antisense oligonucleotides (ASOs) are currently in clinical trials designed to turn off the HSD17B13 gene in non-carriers.
By “breaking” the HSD17B13 pathway, researchers hope to give every patient with liver disease the same biological shield that nature gave to carriers of the TA variant.
Practical Note: The Power of Protection
Genetic testing is actionable. Knowing a patient has the "TA" protective variant can significantly alter the clinical prognosis. It explains why some patients with massive liver fat (steatosis) never develop serious liver damage, while others progress rapidly.
Mimicking the gene. For non-carriers, the development of HSD17B13 inhibitors is one of the most exciting areas of "precision medicine." If successful, these drugs could provide the same "shield" that carriers are born with.
Relevant Research Papers
Links go to PubMed (abstracts are public); some papers also offer free full text via PMC or the publisher.
The foundational study that discovered the rs72613567 insertion and proved its powerful protective effect against cirrhosis.
Established that the genetic protection of HSD17B13 extends beyond scarring to the prevention of liver cancer.
Review article summarizing the localization of the enzyme to lipid droplets and its role in hepatic stellate cell activation.
Clinical progress report showing that therapeutic silencing of HSD17B13 is feasible and safe in humans.
Comprehensive overview of the complex genetic interactions between the most important drivers of hepatic health.