Overall, but not cardiovascular disease, mortality was associated with the PNPLA3 148M allele, and both mortality outcomes were associated with higher fat and fibrosis scores.
In individuals with diabetes and NAFLD, PNPLA3 gene rs738409 C > G polymorphism is a marker for the risk of significant liver fibrosis and cardiovascular disease and may be associated with better glycemic control.
Second, although the strongest genetic risk alleles for NAFLD (ie, the 148Met allele in PNPLA3 and the 167Lys allele in TM6SF2) are associated with increased liver fat content and progression to NASH and cirrhosis, these alleles are also unexpectedly associated with an apparent protection from cardiovascular disease.
We used instrumental variable analysis based on two single nucleotide polymorphism (SNPs) HSD17B13/MAPK10 (rs6834314) and PNPLA3/SAMM50 (rs738409) to assess the associations of ALT (U/L) with IHD, diabetes and other CVD risk factors in the Guangzhou Biobank Cohort Study (GBCS).
In a few cases (e.g., patatin-like phospholipase domain-containing 3/adiponutrin), steatosis carries a high risk of both liver disease and cardiovascular morbidity/mortality; in other cases (e.g., transmembrane 6 superfamily 2 human gene), dissociation has been observed between the increased risk of liver disease versus cardiovascular disease.
This implies that NAFLD is heterogeneous and that "Obese/Metabolic NAFLD" but not NAFLD due to the PNPLA3 or TM6SF2 genetic variants predisposes to type 2 diabetes and cardiovascular disease.
Recent advances include the identification of PNPLA3 as a modifier of disease outcome across the full spectrum of NAFLD from steatosis to advanced fibrosis and hepatocellular carcinoma; and the discovery of TM6SF2 as a potential "master regulator" of metabolic syndrome outcome, determining not only risk of advanced liver disease, but also cardiovascular disease outcomes.