Genetic Variants in <em>PNPLA3</em> and Risk of Non-Alcoholic Fatty Liver Disease in a Han Chinese Population

<div><p>We investigated the possible association between genetic variants in the Patatin like phospholipase-3 (<em>PNPLA3</em>) gene and nonalcoholic fatty liver disease (NAFLD) in a Han Chinese population. We evaluated twelve tagging single-nucleotide polymorphisms (tSNPs) of the <em>PNPLA3</em> gene in a frequency matched case–control study from Fuzhou city of China (553 cases, 553 controls). In the multivariate logistic regression analysis, the rs738409 GG or GC, and rs139051 TT genotypes were found to be associated with increased risk of NAFLD, and a significant trend of increased risk with increasing numbers of risk genotype was observed in the cumulative effect analysis of these single nucleotide polymorphisms. Furthermore, haplotype association analysis showed that, compared with the most common haplotype, the CAAGAA<b>TG</b>CGTG and CGAAGG<b>TG</b>TCCG haplotypes conferred a statistically significant increased risk for NAFLD, while the CGGGAA<b>CC</b>CGCG haplotype decreased the risk of NAFLD. Moreover, rs738409 C>G appeared to have a multiplicative joint effect with tea drinking (P<0.005) and an additive joint effect with obesity (Interaction contrast ratio (ICR) = 2.31, 95% CI: 0.7–8.86), hypertriglyceridemia (ICR = 3.07, 95% CI: 0.98–5.09) or hypertension (ICR = 1.74, 95% CI: 0.52–3.12). Our data suggests that <em>PNPLA3</em> genetic polymorphisms might influence the susceptibility to NAFLD development independently or jointly in Han Chinese.</p> </div

Associations of the <i>FABP1</i> gene promoter variant rs2919872G>A with investigated parameters.

<p>Continuous variables are expressed as mean ± standard deviation (SD); <i>n</i>: number of individuals</p><p><i>P</i>-values a: obtained by one-way ANOVA</p><p>b: obtained by Kruskal–Wallis test or Mann-Whitney U-test</p><p>c additive model: GG vsGA. GG vs AA, and GA vs. AA</p><p>d:a dominant model: GG vs AA+GA</p><p>e: a recessive model (GA+GG vs.AA)</p><p>Associations of the <i>FABP1</i> gene promoter variant rs2919872G>A with investigated parameters.</p

Variables independently associated with plasma TG levels by multivariate lineal regression analysis.

<p>a: Only the variable rs2919872G>A was entered into this model</p><p>b: Variables were selected by a forward stepwise selection procedure, in which variables were sequentially entered into this model.</p><p>c: All variables were entered into this model in a single step.</p><p>Variables independently associated with plasma TG levels by multivariate lineal regression analysis.</p

Associations between risk of NAFLD and frequencies of inferred haplotypes on the basis of the observed genotypes in NAFLD cases and controls.

a<p>In the order of rs738407, rs734561, and rs2006943);</p>b<p>In the order of rs1883350, rs2076208, rs3810622 and rs2294918;</p>c<p>In the order of rs2076212, rs139047, rs9625961, rs738407, rs734561, rs2006943, rs139051, rs738409, rs1883350, rs2076208, rs3810622, and rs2294918.</p>d<p>p value was adjusted by multiple comparisons corrections; e:OR (odds ratio) was adjusted for sex, age, body mass index and other clinical characteristics; CI: confidence interval.</p>f<p>All other haplotypes that had frequency <2% in either cases or controls were pooled.</p

Cumulative effect of adverse genotypes in PNPLA3 rs738409 and rs139051 on NAFLD.

a<p>Risk genotypes were GC/GG for rs734089 and TT for rs139051.</p>b<p>Individuals with no risk genotype were set as the reference group. OR (odds ratio) was determined using logistic regression and adjusted for sex, age, body mass index and other clinical characteristics; CI: confidence interval.</p>c<p><i>P</i>-value based on the Wald test;</p

Combined effects^a of <i>PNPLA3</i> polymorphisms and environmental and ‘internal’ exposures on the risk of NAFLD.

a<p>Included ORs and their corresponding 95% CIs.</p>b<p>Adjusted for age, sex, education, marriage, smoking, income status, and other confounding characteristics.</p

Serum FABP1 levels in healthy individuals with different <i>FABP1</i> rs2919872 genotypes.

<p>Serum FABP1 levels (geometric mean ± geometric standard deviation) were measured among the subjects with different genotypes of the <i>FABP1</i> rs2919872G>A (GG genotype: 13.67 ± 2.60 ng/mL (n = 53); GA genotype: 9.44 ± 2.29 ng/mL (n = 32); AA genotype: 5.13 ± 4.38 ng/mL (n = 10); *<i>P</i> < 0.01)</p

Variables independently associated with plasma FABP1 levels by multivariate lineal regression analysis.

<p>All variables were entered into this model in a single step.</p><p>Variables independently associated with plasma FABP1 levels by multivariate lineal regression analysis.</p

Association between the genotypes of rs738409 and rs139051 and risk of NAFLD.

<p>n: number of individuals; OR (odds ratio) was determined using logistic regression and adjusted for sex, age, body mass index and other clinical characteristics; CI: confidence interval.</p>a<p>P-value based on the Wald test.</p

SNPs in the <i>FABP1</i> gene promoter.

<p>A. Schematic diagram showing the positions of SNPs and known binding sites for nuclear factors. Four SNPs (SNP1 to SNP4), located at -2,055 nt, -1,647 nt, -1,298 nt, and -1,036 nt respectively, were genotyped within the FABP1 promoter (-2,125 nt/+51 nt). The known binding sites for C/EBPα (CCAAT-element binding protein alpha), HNF3β (human nuclear factor beta), DR1-C/EBP (direct repeat with 1 base spacing/CCAAT-element binding protein), PPARα (peroxisome proliferator-activated receptor alpha) in the <i>FABP1</i> gene promoter have been reported previously [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139417#pone.0139417.ref019" target="_blank">19</a>,<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0139417#pone.0139417.ref023" target="_blank">23</a>]. B. SNP information. SNP1 to SNP4 are listed from 5′–3′ of the FABP1 promoter. “CHR-ID” indicates the chromosome ID of the four SNPs in the <i>FABP1</i> gene promoter. “RS ID”, reported in UCSC or NCBI website. “Function” indicates the altered genetically-coded function of the SNPs. “Ref SNP” indicates SNP form in the original reference sequence. “mRNA location” corresponding mRNA positions are shown for each SNP. NCBI db is available from <a href="http://www.ncbi.nlm.nih.gov/SNP" target="_blank">http://www.ncbi.nlm.nih.gov/SNP</a>.</p