👤 B Zinman

Common polymorphisms in the promoter of the APOC3 gene have been associated with hypertriglyceridemia and may impact on phenotypic expression of the metabolic syndrome (MetS). The rs7566605 marker, located near the INSIG2 gene, has been found to be associated with obesity, making it also a potential genetic determinant for MetS. The objective of this study is to examine the APOC3 -455T>C and the INSIG2 rs7566605 polymorphisms as potential genetic determinants for MetS in a multi-ethnic sample. Subjects were genotyped for both the APOC3 -455T>C and INSIG2 rs7566605 polymorphisms, and classified for the presence or absence of MetS (NCEP ATP III and IDF definitions). The total study population included 2675 subjects (> or =18 years of age) from six different geographical ancestries. For the overall study population, the prevalence of MetS was 22.6% (NCEP ATP III definition). Carriers of > or =1 copy of APOC3 -455C were more likely to have MetS (NCEP ATP III definition) than noncarriers (carrier odds ratio 1.73, 95% CI 1.40 to 2.14, adjusting for age and study group). The basis of the association was related not only to a higher proportion of -455C carriers meeting the triglyceride and high-density lipoprotein cholesterol criteria, but also the blood pressure criteria compared with wild-type homozygotes. Plasma apo C-III concentrations were not associated with APOC3 -455T>C genotype. The INSIG2 rs7566605 polymorphism was not associated with MetS or measures of obesity. Meta-analysis of the sample of multiple geographic ancestries indicated that the functional -455T>C promoter polymorphism in APOC3 was associated with an approximately 2-fold increased risk of MetS, whereas the INSIG2 rs7566605 polymorphism was not associated with MetS. Show less

To determine the prevalence of 'hypertriglyceridemic waist' (HTGW) in Oji-Cree, to examine its interaction with hepatic nuclear factor-1alpha (HNF1A) in association with type 2 diabetes, and to characterize its putative genetic determinants. The presence or absence of HTGW was determined in 522 Oji-Cree subjects (223 males, 299 females), >or=18 years of age, in whom physical measurements and fasting plasma analyte concentrations were gathered, and a 75-g oral glucose tolerance test was administered, as part of a cross-sectional study. Subjects were genotyped for HNF1A codon 319, angiotensinogen (AGT) codons 174 and 235, G-protein beta3-subunit (GNB3) nucleotide 825, fatty acid-binding protein (FABP2) codon 54, nucleotides -455 and -482 of the apolipoprotein (apo) C-III (APOC3) promoter, and a 5-bp insertion/deletion polymorphism within the 3'-untranslated region of protein phosphatase 1 regulatory subunit 3 (PPP1R3). The unadjusted prevalence of HTGW in Oji-Cree adults was 20.5%, with more males affected than females (27.8 vs 15.1%, P=0.0004). Logistic regression analysis, adjusted for age and gender, showed type 2 diabetes was associated with both HNF1A G319S (odds ratio (OR) 4.85, 95% CI 2.45, 9.58) and HTGW (OR 4.96, 95% CI 2.49, 9.88). When the HNF1A mutation and HTGW were present in combination, the OR for type 2 diabetes was markedly increased (OR 43.2, 95% CI 12.4, 150). In women only, both GNB3 825C>T and FABP2 A54T genotypes were significantly associated with HTGW (OR 2.02, 95% CI 1.01, 4.05 and OR 1.95, 95% CI 1.01, 3.74, respectively). HTGW is prevalent in Oji-Cree, especially in men. The ORs for type 2 diabetes were similar ( approximately 5-fold) for subjects with either the presence of HTGW or the private HNF1A G319S mutation. These two independent risk factors acted synergistically to confer an even greater increased risk of type 2 diabetes. Show less

The prevalence rates of type 2 diabetes (T2DM) and coronary heart disease (CHD) in Ontario Oji-Cree are among the world's highest. Since metabolic syndrome (MetS) increases risk of T2DM and CHD, we characterized prevalence and putative genetic determinants of MetS in Oji-Cree. In 515 adult (> or = 18 years old) and 115 adolescent (< 18 years old) Oji-Cree subjects, using the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) criteria, we determined that 29.9% of Oji-Cree adults, and 43.4% of adults > or = 35 years of age, had MetS. Furthermore, 33.9 and 8.7% of female Oji-Cree adults and adolescents, respectively, had MetS. Increased waist girth and depressed HDL cholesterol were the most prevalent individual MetS components, while increased blood pressure was least prevalent. AGT T174M, GNB3 825C>T, and APOC3 -455T>C genotypes were significantly associated with MetS (P = 0.018, 0.0056, and 0.029, respectively) for female adults, whereas FABP2 A54T genotype was associated with MetS (P = 0.040) for female adolescents. The high MetS prevalence in Oji-Cree adults, especially women, is consistent with their high risk of T2DM and CHD. Functional polymorphisms in three candidate genes for plasma lipoproteins and blood pressure were associated with MetS in adult Oji-Cree. Furthermore, several female adolescents met the adult MetS criteria, suggesting that the genesis of MetS begins in youth, especially among aboriginal females. Show less

We hypothesized that common genomic variation that affected the expression and/or function of the products of the APOC3, APOE, FABP2, and PON1 genes would be associated with variation in biochemical phenotypes in a previously unstudied human sample. We determined genotypes of functional genomic variants of APOC3, APOE, FABP2, and PON1 in 509 adult aboriginal Canadians from an isolated community in Northern Ontario. We tested for genotype associations with plasma lipoprotein traits. We found that (1) common variation at nucleotide -455 of the APOC3 promoter was associated with variation in plasma triglycerides (P = .006) and (2) common variation of APOE determining plasma isoforms of apo E was associated with variation in plasma apo B (P = .009). Analysis of subjects classed by APOC3 markers showed that homozygosity for presence of a C at nucleotide -455 and a T at nucleotide -482 was associated with significantly increased plasma triglycerides in both men and women. Furthermore, this allele was approximately twice as frequent in subjects within the highest quartile of plasma triglycerides as in subjects within the lowest quartile. Since the DNA variation detected by the APOC3 markers affects in vitro expression of the gene product, it is possible that the marker itself caused the associations. However, the associations could also have resulted from linkage disequilibrium with other functional variants in APOC3 or the closely linked APOA1 and/or APOA4 genes. Show less

We hypothesized that common genomic variants would be associated with variation in lipoprotein phenotypes in young subjects. We determined genotypes of FABP2, PON, APOC3, and APOE in 188 aboriginal Canadians, aged 9 to 17 years. We found that 13 of 32 possible genotype-phenotype associations were significant: (1) the FABP2 codon 54 genotype was associated with variation in plasma triglycerides (P = .045); (2) the PON codon 192 genotype was associated with variation in plasma total and LDL cholesterol and apoB (P = .0099, P = .0088, and P = .016, respectively); (3) the APOC3 insulin-response-element genotype was associated with variation in plasma triglycerides, HDL cholesterol, apoA-I, the total cholesterol to HDL cholesterol ratio, and the apoB to apoA-I ratio (P = .0014, P = .0069, P = .045, P = .0021, and P = .0081, respectively); and (4) the APOE restriction isotype was associated with variation in plasma LDL cholesterol, apoB, the total cholesterol to HDL cholesterol ratio, and the apoB to apoA-I ratio (P = .025, P = .034, P = .045, and P = .047, respectively). The average young age and relative absence of age-dependent secondary environmental factors could have eased the identification of small genetic effects on lipoprotein phenotypes in this study sample. Show less