Search for Rare Mutations in Metabolic Pathways Associated with Nonalcoholic Fatty Liver Disease: The role of Glucokinase regulator (GCKR) Sequence Variation

FERNADEZ GIANNOTTI T; CASTANO GO; SOOKOIAN S; ROHR C; DOPAZO H; PIROLA CJ

Washington DC, USA

Congreso; The 68th Annual Meeting of the American Association for the Study of Liver Diseases: The Liver Meeting 2017; 2017

American Association for the Study of Liver Diseases

Background: Exploration of plasma metabolome revealed that patients with NAFLD and Metabolic Syndrome show deregulated levels of amino acids, including enhanced glutamic acid/glutamine ratio. NAFLD is associated with altered transamination reactions, changes in the expression of genes of the mitochondrial oxidative phosphorylation chain, as well as metabolic perturbations at the Krebs cycle (TCA) level. Furthermore, significant progress towards understanding the genetic component of NAFLD has been made, which uncovered common variants associated with small effects on the disease susceptibility/severity. We hypothesized that the discovery of rare disease-associated variants in metabolic enzyme genes might be a novel mechanism to explain the NAFLD phenotype. Hence, we performed an exploration of sequence variation in fourteen genomic loci that encode metabolic enzymes of the TCA-cycle, which included enzymes of the mitochondrial matrix involved in glutamine and glutamate metabolism (GLUD1/GLUD2/GLUL/GLS GLS2), ACO2 (involved in the second step of the TCA-cycle), DLST (2-oxoglutarate-dehydrogenase complex), isocitrate (IDH1/IDH2/IDH3A/IDH3B), malate and oxoglutarate dehydrogenases (MDH1 and OGDH), and glucokinase regulator (GCKR). Methods: Sequencing of exons, exon-intron boundaries and 5´ and 3´-UTR regions (62.1 Kb) was performed by next-generation sequencing (> 60X coverage). Patients with NAFLD diagnosed by liver biopsy were included (n = 64); subjects without NAFLD/MetS (n =32) served as controls.Results: Deep sequencing revealed a total of 132 single nucleotide polymorphisms (SNPs), including 17 novel SNPs. Clinical associations focused on nonsynonymous-SNPs showed a rare frameshift mutation in exon 9 of GCKR (rs149847328 p.Arg227Ter, MAF