PNPLA3 Genotype, Diabetes Predict Cirrhosis in NAFLD

Patients with nonalcoholic fatty liver disease (NAFLD) who carry two copies of the PNPLA3 p.I148M variant, may exhibit faster progression to cirrhosis, while those with this genotype who also have diabetes and indeterminate Fibrosis-4 (FIB4) scores may have the same risk of cirrhosis as patients with a high FIB4, according to investigators.

These findings suggest that NAFLD patients with indeterminate FIB4 and metabolic risk factors should routinely undergo PNPLA3 genotyping, lead author Vincent L. Chen, MD, of the University of Michigan, Ann Arbor, and colleagues reported.

“Whether incorporating genetics into risk stratification results in meaningful improvement over clinical predictors, such as FIB4, diabetes, and obesity status, is unknown,” the investigators wrote in Gastroenterology. “Improved understanding of how genetics influences the rate of disease progression and how it interacts with established risk factors for advanced liver disease is crucial for genetic testing to be applicable in clinical practice.”

To evaluate the risk presented by the PNPLA3 p.I148M variant, Dr. Chen and colleagues analyzed data from two independent cohorts with 7,893 patients and 46,880 patients each.

They first characterized the relationship between PNPLA3 genotype and cirrhosis via univariable and multivariable analyses. These efforts revealed that the genotype predicted cirrhosis in both cohorts, with associations also detected for well-documented clinical risk factors, including diabetes, obesity, and high ALT. Of note, PNPLA3 genotype demonstrated an additive effect for cirrhosis when detected in conjunction with these risks.

Further analysis revealed that homozygous carriers of PNPLA3 p.I148M with indeterminate FIB4 scores (1.3-2.67) and diabetes had an incidence rate of cirrhosis on par with patients who had high-risk FIB4 (greater than 2.67).

The effects of the risk allele were also made evident by comparing patients with diabetes and indeterminate FIB4 based on presence or absence of the marker – those testing positive for h PNPLA3 p.I148M had 2.9-4.8 times greater risk of cirrhosis. Conversely, patients with FIB4 scores less than 1.3, regardless of other risk factors, had little change in cirrhosis rate regardless of PNPLA3 status.

“We found that PNPLA3 genotyping in conjunction with clinical risk factors may improve risk stratification in patients with NAFLD,” the investigators concluded. “Although it may be possible to develop more complex polygenic risk scores for cirrhosis, these findings suggest that genotyping of PNPLA3 alone, which is less expensive than genomewide genotyping and easier to understand, may have similar clinical applicability for NAFLD.”

Dr. Chen and colleagues therefore recommended that NAFLD patients with metabolic risk factors (particularly diabetes) and indeterminate FIB4 routinely undergo PNPLA3 genotyping, with referral to hepatology if positive for two risk alleles.

The study was supported by the American Association for the Study of Liver Diseases, National Institutes of Health, and the University of Michigan department of internal medicine. The investigators disclosed no conflicts of interest.

This article originally appeared on, part of the Medscape Professional Network.

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