中国人内源性高甘油三酯血症与载脂蛋白A5基因-1131T>C多态性、S19W多态性的相关性

目的探讨中国人内源性高甘油三酯血症患者载脂蛋白A5基因的-1131T〉C多态性及S19W多态性与血脂水平的关系。方法用聚合酶链反应-限制性片断长度多态性分析，对182名内源性高甘油三酯血症患者和200名血脂正常者的载脂蛋白A5基因启动子上游-1131T〉C单核苷酸多态性、编码区的S19W（c．56C〉G）多态性、空腹血脂及载脂蛋白水平进行分析。结果患者的体质指数、血清总甘油三酯和总胆固醇水平较对照组显著升高，高密度脂蛋白胆固醇水平则显著降低。-1131T／C单核苷酸多态性位点T和C等位基因频率在病例组和对照组分别为52．7％、47．3％和67.0％、33．0％。等位基因频率和基因型频率分布符合Hardy-Weinberg平衡定律。T/C基因多态性等位基因T和C频率在两组问的差异有显著性（P〈0．05）；S19W多态性与内源性高甘油三酯血症发病风险未见明显相关性。结论载脂蛋白A5基因-1131C等位基因与血清甘油三酯的升高相关。     

Association between DNA variant sites in the apolipoprotein A5 gene and coronary heart disease in Chinese

The recently discovered apolipoprotein A5 ( APOA5 ) gene has been shown to be important in determining plasma triglyceride levels, a major cardiovascular disease risk factor. We searched for possible associations of the APOA5 gene polymorphisms S19W and -1131T>C with coronary heart disease (CHD) in a Chinese population. A total of 483 Chinese CHD patients and 502 control non-CHD subjects were genotyped by polymerase chain reaction-restriction fragment length polymorphism for these 2 single nucleotide polymorphisms. We found that the minor allele 19W was observed only in CHD patients and not in controls, with allelic frequencies of 0.047 and 0.000, respectively ( P < .000001), and the minor allele -1131C was significantly higher in CHD patients than in controls (0.391 vs 0.299, P < .0001). These results suggest that both the S19W and -1131T>C variations in the APOA5 gene are associated with the CHD and appear to be 2 genetic risk factors for CHD susceptibility in Chinese. Moreover, we found that triglyceride levels were significantly higher in -1131C carriers than in -1131T subjects of the control group and that high-density-lipoprotein cholesterol was decreased in -1131C carriers among CHD patients.     

The -1131 T>C and S19W APOA5 gene polymorphisms are associated with high levels of triglycerides and apolipoprotein C-III, but not with coronary artery disease: an angiographic study

High plasma concentrations of triglycerides (TG) and apolipoprotein C-III (ApoC-III) are well-known risk factors for cardiovascular disease. Two variants of the recently discovered APOA5, 1131 C>T and S19W, have been associated with hypertriglyceridemia, whereas their relation with coronary artery disease (CAD) remains controversial. Nine hundred and thirteen angiografically defined patients (669 CAD and 244 CAD-free) were genotyped for APOA5 -1131 C>T and S19W polymorphisms. Carriership of the APOA5 -1131 C allele was identified, by multiple linear regression models, as a significant independent predictor for both TG (standardized beta-coefficient=0.112; p=0.010) and ApoC-III variability (standardized beta-coefficient=0.113; p=0.013). Similarly, APOA5 19W allele carriership was a significant independent predictor for both TG (standardized beta-coefficient=0.113; p=0.007) and ApoC-III variability (standardized beta-coefficient=0.088; p=0.045). Despite the association with at-risk lipid profile, no significant difference was detected in the distribution of both APOA5 gene polymorphisms between subjects with or without CAD. Moreover, homozygous carriers of the APOC3 -455 C, another TG- and ApoC-III raising variant, showed a significant increased risk for CAD (OR 1.90 with 95% CI 1.002-3.62; p=0.049; by multiple logistic regression). Different genotypes, i.e., APOA5 and APOC3 variants, may lead to similar biochemical phenotypes, namely hypertriglyceridemia, but to contrasting clinical phenotypes such as the presence of angiographically proven CAD.     

Rare APOA5 mutations--clinical consequences, metabolic and functional effects: an ENID review

In 2001, a gene encoding a novel apolipoprotein (apo), APOA5, was identified by comparative human/mouse sequencing. The encoded protein, apoAV, had been missed in routine apolipoprotein identification because it occurs at very low plasma concentrations and only DNA analysis led to its identification. Knockout and transgenic mouse models of apoAV showed an inverse relationship with plasma triglyceride levels. In human studies, common APOA5 variants have shown near consistent association with elevated plasma TG levels, confirming apoAV as playing a role in human triglyceride metabolism. Based on mouse knockout models it was predicted that individuals with rare mutations in APOA5 would present with severe hypertriglyceridaemia and apoAV deficiency. However, considering the small number of mutation carriers identified to date, the mode of inheritance is variable and in the recessive form TG levels are within the normal range, and apoAV deficiency only occurs in the homozygous state. Furthermore, penetrance of the mutations is low and appears to require co-inheritance of a common APOA5 TG-raising allele as well as environmental factors for expression of the hypertriglyceridaemia. In this review the clinical and metabolic consequences and phenotype of the three APOA5 mutations reported to date, which lead to premature truncations of apoAV are described. The insight these truncated protein give to the structure-function relationship of apoAV is explored and the relative importance of plasma and liver apoAV discussed.     

Impact of APOA5/A4/C3 genetic polymorphisms on lipid variables and cardiovascular disease risk in French men

OBJECTIVE: The goal of the present study was to assess the impact of 4 single nucleotide polymorphisms (SNPs) of APOA5/A4/C3 gene cluster on lipid levels and coronary heart disease (CHD) risk in French men. METHODS: A total of 442 men with CHD were recruited from the university hospital and compared to 475 men free of CHD from the population of the same geographical area. The APOA5 S19W, APOA5 -l2,238T>C, APOA4 T347S and APOC3 -482C>T SNPs were examined. RESULTS: The APOA5 S19W polymorphism was associated with plasma triglyceride levels. In multivariate logistic regression analyses the odds ratio (OR [95% Cl]) of hypertriglyceridemia (3rd vs. 1st tertile of triglyceride distribution) was 3.60 [1.38-9.42] in control subjects bearing at least one APOA5 19W variant. Haplotype analyses revealed a significant association between the 2111 haplotype and high triglyceride levels (+1.94 +/- 0.63 vs. 0.74 +/- 0.36 mmol/l for the 1111 haplotype p < 0.002). There was, in contrast, no significant difference in SNP distribution between CHD patients and controls. The age-adjusted OR of CHD were 1.46 [0.96-2.23], 0.79 [0.60-1.05], 0.91 [0.69-1.21] and 0.91 [0.69-l.22] in carriers of the APOA5 19W, APOA5 -12,238C, APOA4 347S and APOC3 -482T variants, respectively. There was also no significant difference in APOA5/A4/C3 haplotype distribution in patients and controls. CONCLUSION: The APOA5 19W variant is associated with increased plasma triglycerides. However, there is no evidence that APOA5 S19W, -12,238T > C, APOA4 T347S and APCC3 -482C > T SNPs are major risk factors of CHD in French men.     

Apolipoprotein AV gene polymorphisms (T-1131/C and Ser19/Trp) influence plasma triglyceride levels and risk of myocardial infarction

BACKGROUND:

The importance of an apolipoprotein AV (apoAV) gene for plasma triglyceride (TG) level determination has been shown on transgenic and knockout mice.The influence of apoAV polymorphisms (T-1131/C and Ser19/Trp) on plasma TG levels was evaluated in a representative sample of 1191 men and 1368 women, in 435 patients with myocardial infarction (MI) and in 83 individuals with extreme TG levels (20.4±12.8 mmol/L).

METHODS:

ApoAV variants were analyzed using polymerase chain reaction and restriction analysis.

RESULTS:

T-1131/C variation in the apoAV gene affects plasma TG levels, showing a higher level in C-1131 carriers than in T/T-1131 homozygotes. This association has been observed both in men (P<0.05) and in women (P<0.01). TG levels were also influenced by the Ser19/Trp apoAV genotypes. In both males and females, the Trp19 carriers have higher plasma TGs (P<0.01) than do Ser19 homozygotes. In hypertriglyceridemic patients, the frequency of carriers of the T/C-1131 and C/C-1131 genotypes (32.5% versus 15.4%, P<0.0001) and Ser/Trp19 and Trp/Trp19 genotypes (30.1% versus 14.1%, P<0.0001) was much higher than in the population sample. In a group of MI patients (n=435), the frequency of the disadvantageous homozygous genotypes, with their effect of increasing the TG concentration (C/C-1131 and/or Trp/Trp19), was significantly higher than in the population sample (7.4% versus 2.0%, P<0.00001).

CONCLUSION:

Variation(s) in the apoAV gene play an important role in the genetic determination of plasma TG levels and influence the risk of MI.     

冠心病患者载脂蛋白A5和载脂蛋白C3基因多态性的研究

目的研究中国北方汉族人群中载脂蛋白A5基因(APOA5)-1131F／C、56C／G多态性和载脂蛋白C3基因(APOC3)-482C／T多态性与冠心病的关系。方法采用聚合酶链反应．限制性片段长度多态性(PCR-RFLP)结合聚丙烯酰胺凝胶电泳(PAGE)技术检测了312例经冠状动脉造影确诊的冠心病患和317例健康对照APOA5-1131T／C、56C／G和APOC3-482C／T多态性基因型和等位基因的分布,同时采用生化方法检测了研究对象的血脂水平。结果冠心病组APOA5-1131C等位基因频率明显高于对照组(39．9％比33．3％,P=0．02)。CC纯合子患冠心病的风险是TT纯合子的1.93倍(95％CI：1．12～3．32),且通过Logistie回归分析发现该相关性独立于性别、年龄、体重指数、吸烟史、高血压糖尿病患病史及血清TC、HDK-C、IDL-C水平;冠心病组CC纯合子的TG水平明显高于TC杂合子,而TT纯合子TG水平最低。虽然APOA5-1131T／C和APOC3—482C／T多态性存在连锁不平衡,但前的作用与后无关。结论APOA5-1131T／C基因多态性对人群血清TG水平有影响,APOA5-1131C等位基因可能与我国北方汉族人冠心病的发生相关联。     

The apolipoprotein A-V genotype and plasma apolipoprotein A-V and triglyceride levels: prospective risk of type 2 diabetes. Results from the Northwick Park Heart Study II

Aims/hypothesis We sought to establish the relationship between plasma apolipoprotein A-V (APOA5, previously known as apoA-V) and triglyceride levels and to determine the impact of the APOA5 genotype on APOA5 levels and development of type 2 diabetes in a 15-year follow-up study of healthy UK men. Materials and methods APOA5 −1131T>C and S19W genotypes were determined in 2,490 men, of whom 145 subsequently developed type 2 diabetes. In a subset of 299 men, we also determined APOA5 levels. Results Plasma APOA5 levels positively correlated with triglycerides (r=0.18, p<0.002) and were not different in men who subsequently developed type 2 diabetes compared with healthy men (p=0.7). Carriers of either APOA5 W19 or −1131C had, as expected, higher plasma triglycerides. However, while W19 carriers had significantly higher APOA5 levels (p=0.0003), APOA5 levels were not associated with −1131T>C (p=0.63), reinforcing the idea that the reported −1131C association with triglycerides levels is due to linkage disequilibrium with variants in the APOC3 gene, and not due to the direct effect on APOA5 levels. Overall no effect of APOA5 −1131T>C or S19W was found on type 2 diabetes risk. Conclusions/interpretation In contrast to animal studies, in man, plasma APOA5 positively correlates with plasma triglyceride levels. In prospective analysis, with the caveat that numbers were small, APOA5 genotypes do not appear to have an impact on risk of development of type 2 diabetes.     

Two independent apolipoprotein A5 haplotypes modulate postprandial lipoprotein metabolism in a healthy Caucasian population

BACKGROUND: Apolipoprotein A5 (APOA5) plays an important role in plasma triacylglycerol (TG) homeostasis. Five polymorphisms (1131T>C, c.-3A>G, c.56C>G, IVS3+476G>A, and c.1259T>C) in the APOA5 gene define three common haplotypes (APOA5*1, APOA5*2, and APOA5*3) in Caucasian individuals. Our aim was to determine whether these haplotypes could modulate the postprandial response in young healthy males. DESIGN AND METHODS: Eighty-eight APO E3/3 volunteers [67 with (-1131T and 56C) APOA5*1 haplotype, 12 with (-1131C and 56C) APOA5*2 haplotype, and nine with (-1131T and 56G) APOA5*3 haplotype] underwent a fat load test consisting of the consumption of 1 g of fat per kilogram body weight and 60,000 IU vitamin A. Blood samples were taken at time 0, at every hour until the sixth hour, and at every 2.5 h until the 11th hour. Total plasma cholesterol (C) and TG, and C, TG, apolipoprotein B-100, apolipoprotein B-48, and retinyl palmitate in lipoprotein fractions were determined. RESULTS: Subjects with the APOA5*2 and APOA5*3 haplotypes had a higher area under the curve of total plasma TG (P = 0.03), large TG-rich lipoprotein (TRL)-TG (P = 0.02), small TRL-TG (P = 0.04), small TRL-C (P = 0.04), large TRL-C (P = 0.03), and small apolipoprotein B100 (P = 0.04) than subjects with the APOA5*1 haplotype. CONCLUSIONS: Our findings show that the presence of the APOA5*2 and APOA5*3 haplotypes in the APOA5 gene is associated with a higher postprandial response that could be involved in the higher risk of coronary heart disease associated with the 56G and -1131C alleles.     

动脉硬化性脑梗死患者载脂蛋白A5基因多态性研究

目的研究载脂蛋白A5基因-1131T>C多态性位点各基因型及等位基因分布频率及其与动脉硬化性脑梗死(arteriosclerotic cerebral infarction,ACI)的关系。方法选择221例湖北地区汉族人群(对照组)及90例ACI患者(ACI组),应用聚合酶链反应限制性片段长度多态性对每个个体的基因型进行鉴定。同时,采用酶法和免疫比浊法对研究对象血脂进行检测。结果2组间除性别、年龄、体重指数无显著差异外,其他各项指标(吸烟、收缩压、舒张压、胆固醇、高密度脂蛋白胆固醇、低密度脂蛋白胆固醇、载脂蛋白A1及载脂蛋白B)均有显著差异(P<0.05);ACI组稀有等位基因C携带者甘油三酯水平明显高于C非携带者,2组中TT、TC、CC 3种基因型甘油三酯水平差异有显著性意义(P<0.05);ACI组稀有等位基因C的频率明显高于对照组(χ2=5.568,P=0.018)。结论apoA5-1131C等位基因与ACI患者甘油三酯水平升高有关,其不同基因型及等位基因在湖北汉族人群及ACI患者中的分布不同,可能与该地区人群ACI危险性有关。     

汉族人载脂蛋白A5基因-1131T＞C多态性与2型糖尿病合并冠心病的相关性研究

目的 探讨我国北方地区汉族人载脂蛋白A5基因（APOA5）-1131T＞C多态性对血脂的影响及其与2型糖尿病合并冠心病的关系.方法 应用聚合酶链反应限制性片段长度多态性（PCR-RFLP）技术检测了136例健康对照者、163例2型糖尿病患者（DM组）和114例经冠状动脉造影确诊的2型糖尿病合并冠心病患者（DM＋CHD组）APOA5-1131T＞C多态性基因型和等位基因频率分布,同时检测了研究对象的血脂、脂蛋白和载脂蛋白水平.结果 健康对照组APOA5-1131T＞C多态性与血清甘油三酯（TG）水平密切相关,C等位基因携带者TG水平明显高于TT基因型（1.38比0.91 mmol/L,P＜0.001）.2型糖尿病合并冠心病组APOA5-1131C等位基因频率明显高于对照组（38.4%比28.3%,P=0.023）,TT、TC、CC基因型频率在DM＋CHD组和对照组分别为33.9%、55.4%、10.7%和50.4%、42.5%、7.1%,两组间差异具有统计学意义（P＜0.05）.而2型糖尿病组和对照组相比,APOA5-1131T＞C多态性基因型频率和等位基因频率分布均无差异.结论 APOA5-1131T＞C多态性对人群TG水平有极显著影响,C等位基因与2型糖尿病合并冠心病的患病风险有一定关系.     

A genetic variant c.553G > T in the apolipoprotein A5 gene is associated with an increased risk of coronary artery disease and altered triglyceride levels in a Chinese population

Elevation in plasma triglycerides (TG) has been widely accepted as a coronary artery disease (CAD) risk predictor. Recently, a new apolipoprotein playing an important role in TG metabolism named apolipoprotein AV (apoAV) was discovered, which is encoded by the APOA5 gene. Several single nucleotide polymorphisms (SNPs) of APOA5 associated with increased TG concentrations have been identified. We here report that a recently identified genetic variant, c.553G>T in the APOA5 gene which causes a substitution of a cysteine for a glycine residue at amino acid residue 185(G185C) is also associated with increased TG levels. To investigate the association between this genetic variation and the risk of CAD, a case-control study comprising 232 patients with CAD and 302 controls from the same area of China was performed. The minor allele frequencies of c.553G > T for the CAD and control groups were 7.76 and 3.97%, respectively (P = 0.008). In both the CAD and control groups, the T allele carriers had higher serum TG levels than homozygous carriers of the major G allele (CAD group: 2.67 +/- 1.48 mmol/l versus 1.95 +/- 1.02 mmol/l, P = 0.021; controls: 2.31 +/- 1.20 mmol/l versus 1.68 +/- 0.95 mmol/l, P = 0.002). After adjustment for age, gender, body mass index, smoking status, glucose and presence of hypertension, the odds ratio (OR) for CAD in the T allele carriers was 2.089 (95% CI = 1.140-3.830, P = 0.017), in comparison to the individuals without the T allele. These results suggest that the APOA5 c.553G > T polymorphism is an important predictor for hypertriglyceridemia and CAD.     

Apoprotein A-V: An important regulator of triglyceride metabolism

Summary Apolipoprotein A-V (apoA-V) was discovered in 2001 both by comparative sequencing and as a liver regeneration protein. The gene is a located at the APOA1/C3/A4/A5 gene cluster on chromosome 11q23, a locus well known for playing a major role in regulating plasma cholesterol and triglyceride (TG) levels. ApoA-V is produced in the liver and has very low plasma concentrations (0.1–0.4 μg/ml). Mice lacking apoA-V have 4-fold increased TG levels, whereas apoA-V overexpression leads to 40% plasma TG reduction. Based on metabolic studies in vivo, apoA-V enhances the catabolism of TG rich lipoproteins rather than affecting their intestinal or hepatic production. By activating proteoglycans-bound lipoprotein lipase (LPL), apoA-V can accelerate TG hydrolysis from VLDL and chylomicrons independent from other apoproteins. Several variants at the APOA5 gene locus have been detected in humans. Some single nucleotide polymorphisms (SNPs) are associated with significantly higher plasma TG levels in patients (e.g., −1131T > C, S19W, G185C). In addition, these SNPs may affect fibrate response and obesity. However, data for a possible association of APOA5 variants with coronary heart disease are not consistent. Severe structural mutations (Q139X, Q148X, IVS3 + 3G > C) predispose to familial hypertriglyceridaemia and late-onset chylomicronaemia. Thus, despite its low plasma concentration, apoA-V is a major regulator of plasma TG metabolism in humans. However, the precise mechanism of its function is not yet clear. Competing interests: None declared Presented at the Annual Symposium of the SSIEM, Hamburg, 4–7 September 2007.     

Apolipoprotein A5 gene IVS3+G476A allelic variant confers susceptibility for development of ischemic stroke

BACKGROUND: T-1131C, T1259C and IVS3+G476A are naturally occurring variants of the apolipoprotein A5 (APOA5) gene and their possible impact on the development of ischemic stroke was investigated in the present study. METHODS AND RESULTS: PCR-RFLP assays were used to determine the distributions of the APOA5 alleles in small-vessel, large-vessel and mixed subgroups of 378 patients and in 131 stroke-free control subjects. Increased triglyceride levels were found in subjects carrying -1131C, 1259C, IVS3+476A alleles in all stroke groups and in the controls. The -1131C and IVS3+476A alleles, but not the T1259C variant, showed significant accumulation in all stroke subgroups. Logistic regression analysis adjusted for age, gender, body mass index, total cholesterol level, ischemic heart disease, hypertension, diabetes mellitus, smoking-and drinking habits revealed that the IVS3+476A allele represents independent susceptibility factor for stroke (odds ratio for small-vessel: 4.748; large-vessel: 3.905; mixed: 2.926; overall: 3.644 at 95% confidence interval; p<0.05), we could also confirm the previously verified pathogenic role of the -1131C variant. CONCLUSIONS: All of the 3 APOA5 variants are associated with elevated triglycerides, but only the -1131C and the IVS3+476A alleles confer risk for all types of ischemic stroke; such an association could not be detected for the 1259C allele.     

Associations of the apolipoprotein A1/C3/A4/A5 gene cluster with triglyceride and HDL cholesterol levels in women with type 2 diabetes

The apolipoprotein gene cluster (APOA1/C3/A4/A5) was recently associated with triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) in non-diabetic population. Little is known whether the variations in these genes affect lipid homeostasis in patients with type 2 diabetes. We examined the associations of 10 polymorphisms at APOA1/C3/A4/A5 gene cluster with blood lipids among 902 diabetic women. A linkage disequilibrium (LD) breakdown was observed between APOA5 and other genes. APOA5 S19W was associated with significantly higher fasting TG levels (P=0.001). Two common haplotypes encompassing four APOA5 polymorphisms (SNP1, SNP2, S19W, and SNP3) were associated with 35.6 mg/dL (haplotype 2212, APOA5*2, P=0.016) and 57.8 mg/dL (haplotype 1121, APOA5*3, P=0.0002) higher fasting TG levels compared with the most common (haplotype 1111, APOA5*1), respectively. Adjustment for age, BMI, and other covariates did not appreciably change such associations. In addition, APOC3 promoter polymorphism -455T/C showed significant associations with fasting TG levels (P=0.006), whereas APOA4 +347T/A showed significant associations with lower levels of HDL-C (P=0.017). Our results indicate that the variability in APOA1/C3/A4/A5 gene cluster may affect TG and HDL levels in women with type 2 diabetes.     

Genetic variations of apolipoprotein A5 gene is associated with the risk of coronary artery disease among Chinese in Taiwan

Recently, a T/C polymorphism of the promoter region of the APOA5 gene at position -1131 and a G/T polymorphism at position 553 were found to be associated with increased levels of plasma triglyceride. Triglyceride plays a role in coronary artery disease (CAD), so this case-control study tested for a possible link between these two APOA5 polymorphisms, their common haplotypes and the risk of CAD. The subjects included 211 CAD patients and 677 unrelated controls. A significantly higher level of triglycerides and a lower level of high-density lipoprotein cholesterol (HDL-C) were noted for carriers with -1131C than for non-carriers (P<0.001 and 0.013, respectively) among controls. Plasma triglyceride levels were significantly higher (P=0.014) in controls with genotypes that contained the c.553T allele than in homozygotes for the G allele. Subjects homozygous for the wild-type haplotype had significantly lower triglyceride levels and higher HDL-C levels than subjects with all other haplotype pairs. The -1131C homozygous carriers and c.553T heterozygous carriers were found more frequently in 211 patients with CAD than in the 317 age/sex-matched controls (P=0.008 and 0.023, respectively) in univariate analysis. The significant association between c.553T allele carriers with CAD remained in multivariate regression analysis (OR, 1.79; CI, 1.07-3.00; P=0.028), after adjustments were made for other risk factors. Notably, haplotype analysis further verified that the APOA5 -1131C and c.553T bi-loci haplotype was significantly overpresented in CAD, as compared to the controls. These results indicate that the variants of APOA5 gene modulate plasma triglyceride and may use them to predict CAD susceptibility in Taiwanese Chinese.     

Contribution of APOA5−1131C allele to the increased susceptibility of diabetes mellitus in association with higher triglyceride in Korean women

Apolipoprotein A5 (APOA5) −1131C allele is associated with higher triglyceride, an independent cardiovascular risk factor and a commonly recognized lipid abnormality in diabetes mellitus (DM). We investigated the association of APOA5 −1131T>C or S19W with DM. Study subjects were all women and categorized into metabolically healthy controls (n = 2033) and DM subjects (n = 304). Association of APOA5 −1131T>C with DM was calculated by odds ratio (OR). Anthropometric parameters, fasting glucose, and lipid profiles were measured. C carriers, particularly those with CC homozygote, had higher triglyceride and lower high-density lipoprotein cholesterol in both healthy controls (P < .001 and P < .001) and DM patients (P = .002 and P = .006) after the adjustment for age, body mass index, menopause, smoking, and drinking. APOA5 −1131C allele was associated with an increased risk of DM (OR, 1.61 [95% confidence interval {CI}, 1.23-2.10]; P < .001) after adjustment for the above confounders. Further adjustment for fasting triglyceride or/and high-density lipoprotein cholesterol attenuated a little bit, but still significantly increased the risk of DM in C carriers (OR₂, 1.36 [95% CI, 1.02-1.80]; P = .035 and OR₃, 1.36 [95% CI, 1.032-1.79]; P = .029, respectively). Interestingly, C allele carriers in DM patients showed a positive correlation between fasting glucose and triglyceride after the adjustment (r = 0.172, P = .035). On the other hand, this significant correlation was not observed in healthy women. Regarding S19W, minor allele was not found in our study population from prescreening test. In conclusion, APOA5 −1131C allele may contribute to the increased susceptibility of DM in Korean women. In addition, positive correlation between fasting glucose and triglyceride in C carriers of DM patients suggested that C allele in hyperglycemic states may be more susceptible to the risk of cardiovascular disease.     

SNPs at the APOA5 gene account for the strong association with hypertriglyceridaemia at the APOA5/A4/C3/A1 locus on chromosome 11q23 in the Northern Irish population

Serum triglyceride levels (TG) are important independent risk factors for coronary heart disease. The apolipoproteins C-III (apoCIII) and A-V (apoAV) are central to normal TG metabolism and the complete sequence analysis of these genes was carried out in severe cases (TG > 9 mmol/l) and controls (TG < 2 mmol/l). A total of 53 SNPs were identified in these genes with 17 being novel to this study. Further analysis defined four APOC3 SNPs and three APOA5 SNPs showing strong association with TG levels. Analysis of the two major SNPs from APOA5 [c.56C > G, c.-3A > G] and from APOC3 [c.102C > T, c.340C > G] using THESIAS has identified two major haplotypes relative to the most common CACC haplotype showing very strong association with hypertriglyceridaemia, CGTG and GATC (odds ratio 7.45 and 5.26). Logistic regression analysis of these four SNPs revealed that, carriage of the APOA5 c.56 G allele (odd ratios 4.49) and the APOA5 c.-3 G allele (odds ratio 3.23) were strong independent predictors of hypertriglyceridaemia (P < 0.001), whereas in contrast, carriage of the APOC3 c102 T allele (odds ratio 1.35) and the APOC3 c.340 G allele (odds ratio 1.37), did not show any significant effects that were independent of APOA5.     

Hypertriglyceridaemia and low plasma HDL in a patient with apolipoprotein A-V deficiency due to a novel mutation in the APOA5 gene

APOA5 encodes a novel apolipoprotein (apo A-V) which appears to be a modulator of plasma triglyceride (TG). In apoA5 knock out mice plasma TG level increases almost fourfold, whereas in human APOA5 transgenic mice it decreases by 70%. Some SNPs in the APOA5 gene have been associated with variations in plasma TG in humans. In addition, hypertriglyceridaemic (HTG) patients have been identified who carried rare nonsense mutations in the APOA5 gene (Q139X and Q148X), predicted to result in apo A-V deficiency. In this study we report a 17-year-old male with high TG and low high density lipoprotein cholesterol (HDL-C), who at the age of two had been found to have severe HTG and eruptive xanthomas suggesting a chylomicronaemia syndrome. Plasma postheparin LPL activity, however, was normal and no mutations were found in LPL and APOC2 genes. The sequence of APOA5 gene revealed that the patient was homozygous for a point mutation (c.289 C>T) in exon 4, converting glutamine codon at position 97 into a termination codon (Q97X). Apo A-V was not detected in patient's plasma, indicating that he had complete apo A-V deficiency. The administration of a low-fat and low-oligosaccharide diet, either alone or supplemented with omega-3 fatty acids, started early in life, reduced plasma TG to a great extent but had a negligible effect on plasma HDL-C. Loss of function mutations of APOA5 gene may be the cause of severe HTG in patients without mutations in LPL and APOC2 genes.