| Objective: Single nucleotide polymorphisms(SNPs),DNA methylation and miRNAs were analyzed to investigate the characteristics of genetics and epigenetics in nonalcoholic fatty liver disease(NAFLD)in Chinese Han population.Methods: Patients with biopsy-proven NAFLD(including chronic hepatis B(CHB)patients with NAFLD)and normal controls were recruited.The candidate genes(APOC3,PPARGC1 A and PNPLA3)SNPs were genotyped by AmpliSeq methods;DNA methylation profile in peripheral leukocytes was analyzed by Illumina 450 K methylation BeadChip and seven specific miRNAs(miR-122,miR-192,miR-16,miR-21,miR-146 b,miR-125 b and miR-27b)were detected in the serum by real-time PCR.Then evaluate the association between SNPs,methylated sites,miRNAs and NAFLD,respectively.Results:(1)A novel APOC3 SNP rs2070666 A allele(TA+AA)and PPARGC1 A rs8192678 A allele were independent risk factor for NAFLD,and remarkably linked to the significant histological steatosis(S2-3)and NASH.Four linked SNPs of PNPLA3,rs738409(C>G),rs738408(C>T),rs4813273(G>A),rs2072906(A>G),and another novel SNP rs1010023(T>C)conferred high risk to NAFLD in CHB patients independent of HBV infection.Four linked SNPs were associated with increased susceptibility to borderline/definitive NASH and liver significant fibrosis.PNPLA3 rs1010023(TC+CC)were correlated with significant lowered levels of serum TG,BMI and FBG in CHB patients with NAFLD.Patients in the CHB+NAFLD group with PNPLA3 SNPs showed significantly lower serum levels of HBV-DNA.(2)Genome-wide DNA methylation was firstly detected in peripheral leukocytes in NAFLD patients,a total of 863 loci with significant differential methylation were obtained in peripheral leukocytes of NAFLD patients,680(78.8%)was hypomethylated.The significant differential hypomethylated genes ACSL4 and CPT1 C which located in adipocytokine signaling pathway were detected by pathway analysis.The hypomethylated levels of ACSL4(cg15536552)and CPT1C(cg21604803)were associated with NAFLD;while the hypomethylated level of ACSL4(cg15536552)was increased the risk for borderline/definite NASH(NAS≥3)in male NAFLD patients at age≤50y.(3)Serum levels of miR-122,miR-192,miR-16,miR-21 and miR-146 b were significant higher in NAFLD patients than in controls,and also remarkably increased in signicant fibrosis patients.MiR-122,miR-192,miR-16 and miR-21 were also significant increased in NASH patients.miR-122 and miR-192 were positively correlated with severe degrees of liver histopathological findings in NAFLD patients.miR-122,miR-192,miR-16,miR-21 and miR-146 b were showed moderate to high diagnostic accuracy for NAFLD.MiR-122,miR-192 and miR-16,miR-192 had moderated diagnostic accuracy for NASH and signicant fibrosis in NAFLD patients,respectively.miR-122+miR-192+miR-16+miR-21+miR-146 b panel increased the accuracy for significant fibrosis in NAFLD.Conclusion:(1)APOC3 novel SNP rs2070666,PPARGC1 A rs8192678,four linked PNPLA3 SNPs rs738409(C>G),rs738408(C>T),rs4813273(G>A),rs2072906(A>G)and novel SNP rs1010023(T>C)were also associated with increased susceptibility to NAFLD.PNPLA3 SNPs associated with NAFLD independent of the effect of HBV infection and may also affect the HBV-DNA viral load.The rs1010023 improved the levels of BMI,TG and FBG in CHB patients with NAFLD.(2)Global hypomethylation in periphral leukocytes in NAFLD of Chinese Han population.The leukocytic hypomethylation of ACSL4(cg15536552)and CPT1C(cg21604803)might be the pathogenesis of NAFLD/NASH.(3)NAFLD is associated with altered serum miRNAs expression pattern.Circulating miRNAs may be a potential biomarker for NAFLD/NASH and provides clues for defining the non-invasive diagnosis.Differernt miRNAs panels may provide a clue to differentiate significant fibrosis in NAFLD patients. |
