We investigated whether the common rs738409 variant in PNPLA3 gene associates with the occurrence of liver-related events and death in a large cohort of patients with NAFLD.
Studies that used common variants in PNPLA3, TM6SF2 and GCKR as instruments to investigate the relationship between NAFLD and coronary artery disease (CAD) have reported contrasting results.
In addition, genetic variants predisposing to NAFLD, such as the PNPLA3I148M mutation, were not consistently associated with an increased risk of cardiovascular events.
In a sample of 230 overweight/obese children, 105 with NAFLD (hepatic fat fraction ≥5% by magnetic resonance imaging) and 125 without NAFLD, rs738409 in PNPLA3, rs58542926 in TM6SF2, rs1260326 in GCKR, and rs641738 in MBOAT7 were genotyped.
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.
Mendelian randomization using GWAS meta-analysis data was performed to estimate the causal effect of non-alcoholic fatty liver disease (PNPLA3, LYPLAL1, NCAN, GCKR) on eGFR (N<sub>max</sub> 118,460), microalbuminuria (N<sub>max</sub> 54,116), and impaired renal function (N<sub>max</sub> 118,147).
The pathogenesis of non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC) has been associated with altered expression of liver-specific genes including pyruvate kinase liver and red blood cell (PKLR), patatin-like phospholipase domain containing 3 (PNPLA3) and proprotein convertase subtilisin/kexin type 9 (PCSK9).
The PNPLA3I148M variant was significantly associated with the risk of NAFLD in an additive model (CG, OR = 2.092, 95% CI: 1.551-2.820, P = 0.000; GG, OR = 4.566, 95% CI: 3.141-6.638, P = 0.000, respectively).
We measured comprehensive lipoprotein profiles by nuclear magnetic resonance among 170 serially recruited patients in an NAFLD registry, and determined their relationships with PNPLA3 and TM6SF2 genotypes.
Children with obesity and PNPLA3 MM genotype show lower eGFR levels compared with other genotypes, with a major effect of this polymorphism in the presence of NAFLD.
Three of the 14 SNPs were significantly associated with paediatric NAFLD after FDR adjustment, rs738409 (PNPLA3, P = 2.80 × 10<sup>-06</sup> ), rs1044498 (ENPP1, P = 0.0091) and rs780094 (GCKR, P = 0.0281).
Among the eleven genotyped SNPs, the genetic variants in TM6SF2 rs58542926 (OR = 4.13, p = 0.002), GCKR rs1260326 (OR = 1.53, p = 0.003), PNPLA3rs738409 (OR = 1.58, p = 0.004) and ELOVL2 rs2236212 (OR = 1.34, p = 0.047) were significantly associated with a higher risk of NAFLD.
CONCLUSION: Our study demonstrates the key role of hepatic Elovl6 in the regulation of the acyl-chain composition of ceramide, and that C18:0-ceramide is a potent regulator of hepatic insulin signaling linked to Pnpla3-mediated NAFLD.
The results revealed the potential mechanism underlying the effects of DAP on NAFLD in vitro: i) By increasing the phosphorylation of AMPK, DAP inhibited the expression of SREBP‑1C and PNPLA3, and induced that of PPARα.
An I148 M variant in patatin-like phospholipase domain-containing protein 3 (PNPLA3) and an E167K variant in transmembrane 6 superfamily 2 (TM6SF2) are major genetic risk factors for the development and progression of NAFLD.