Recently the SNP identified as rs1260326, in the glucokinase regulatory protein (GCKR) was associated with hypertriglyceridemia in adults. Since accumulation of triglycerides in hepatocytes represents the hallmark of the steatosis, we aimed to investigate whether this variant might be associated with fatty liver (hepatic fat content, HFF%). Moreover, since recently rs738409 in the PNPLA3 and rs2854116 in the APOC3 were associated with fatty liver recently, we explored how the GCKR SNP and these two variants jointly influence hepatosteatosis.
Methods and Results
We studied 455 obese children and adolescents (181 Caucasians, 139 African Americans and 135 Hispanics). All underwent an OGTT and fasting lipoprotein subclasses measurement by proton NMR. A subset of 142 children underwent a fast gradient MRI to measure the HFF%.
The rs1260326 was associated with elevated triglycerides (Caucasians p=0.00014; African Americans p=0.00417) large VLDL (Caucasians p=0.001; African Americans p=0.03) and with fatty liver (Caucasians p= 0.034; African Americans p= 0.00002; and Hispanics p= 0.016). The PNPLA3, but not the APOC3 rs2854116 SNP, was associated with fatty liver but not with triglycerides levels. There was a joint effect between the PNPLA3 and GCKR SNPs, explaining 32% of HFF% variance Caucasians (p=0.00161), 39.0% in African Americans (p=0.00000496), and 15% in Hispanics (p=0.00342).
The rs1260326 in GCKR is associated with hepatic fat accumulation along with large VLDL, and triglycerides levels. GCKR and PNPLA3 act together to convey susceptibility to fatty liver in obese youths.