Identification of genetic variation that determines levels of plasma triglycerides and hypercoagulability

Genes and abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a multifactorial disease with a strong genetic component. Since the first candidate gene studies were published 20 years ago, approximately 100 genetic association studies using single nucleotide polymorphisms (SNPs) in biologically relevant genes have been reported on AAA. These studies investigated SNPs in genes of the extracellular matrix, the cardiovascular system, the immune system, and signaling pathways. Very few studies were large enough to draw firm conclusions and very few results could be replicated in another sample set. The more recent unbiased approaches are family-based DNA linkage studies and genome-wide genetic association studies, which have the potential of identifying the genetic basis for AAA, only when appropriately powered and well-characterized large AAA cohorts are used. SNPs associated with AAA have already been identified in these large multicenter studies. One significant association was of a variant in a gene called contactin-3, which is located on chromosome 3p12.3. However, two follow-up studies could not replicate this association. Two other SNPs, which are located on chromosome 9p21 and 9q33, were replicated in other samples. The two genes with the strongest supporting evidence of contribution to the genetic risk for AAA are the CDKN2BAS gene, also known as ANRIL, which encodes an antisense ribonucleic acid that regulates expression of the cyclin-dependent kinase inhibitors CDKN2A and CDKN2B, and DAB2IP, which encodes an inhibitor of cell growth and survival. Functional studies are now needed to establish the mechanisms by which these genes contribute toward AAA pathogenesis.

Prevalence and risk factors associated with dyslipidaemia in children and adolescents among ethnic groups in Taiwan

BACKGROUND

The mortality rates of cerebral and cardiovascular diseases are higher for aborigines than non-aborigines in Taiwan. Hypertriglyceridaemia and hypercholestolaemia are risk factors for cardiovascular diseases.

OBJECTIVES

To investigate the prevalence of dyslipidaemia and its associated risk factors in aborigine (Atayal, Paiwan and Bunun tribes) and non-aborigine (Fukein and Hakka Chinese) children and adolescents in Taiwan.

STUDY DESIGN

This was a cross-sectional study.

METHODS

In total, 718 males and 721 females, below 20 years of age, were recruited. Our study defined dyslipidaemia as serum triglyceride and cholesterol levels greater than 200 and 240 mg/dl, respectively.

RESULTS

The serum triglyceride level and the prevalence of hypertriglyceridaemia were similar in both aborigines and non-aborigines and both sexes, but the Bunun and Paiwan tribes had the highest prevalence of hypertriglyceridaemia in males (11.8-29.4%) and females (10.9-22.8%) compared with other aboriginal tribes (5.1-10.8% for males and 7.8-9.2% for females). Serum cholesterol concentrations and the prevalence of hypercholesterolaemia were lower in the aborigines than non-aborigines for both sexes (P<0.05), with the Atayal tribe having the lowest prevalence in males (1.1%) and females (2.1%) compared with other aboriginal tribes (2.4-4.5% for males and 5.7-8.0% for females). Using multivariate-adjusted logistic regression modelling, hypertriglyceridaemia was significantly associated with the Bunun tribe (odds ratio (OR)=3.2, 95% confidence intervals (CI) 1.6-6.1), hyperuricaemia (OR=1.8, 95% CI 1.2-2.6), hypercholesterolaemia (OR=3.3, 95% CI 1.7-6.4) and alcohol use (OR=2.8, 95% CI 1.2-6.6). Hypercholesterolaemia, after controlling for age and sex, was significantly associated with the Atayal tribe (OR=0.2, 95% CI 0.1-0.5), hypertriglyceridaemia (OR=3.5, 95% CI 1.8-6.7) and hyperuricaemia (OR=3.2, 95% CI=1.7-6.0).

CONCLUSIONS

For the young people of Taiwan, hypertriglyceridaemia is associated with hyperuricaemia, hypercholesterolaemia and alcohol use, and hypercholesterolaemia is associated with hypertriglyceridaemia and hyperuricaemia. Compared with non-aborigines, the young aborigines of some tribes have a higher prevalence of hypertriglyceridaemia and a lower serum cholesterol level.

Unravelling the familial tendency to aneurysmal disease: popliteal aneurysm, hypertension and fibrillin genotype

PURPOSE

To screen patients with abdominal aortic aneurysm for popliteal aneurysm and investigate cardiovascular and genetic risk factors associated with aneurysmal disease at more than one site (generalised aneurysmal disease). SUBJECTS, DESIGN AND SETTING: All patients referred to the Regional Vascular Surgical Service at Charing Cross Hospital with unruptured abdominal aortic aneurysm between 1989 and 1993 were screened for popliteal aneurysms, using ultrasonography.

MAIN OUTCOME MEASURES

Palpation of a popliteal aneurysm or ultrasonographic detection of popliteal dilatation, where the ratio maximum popliteal fossa diameter/suprageniculate popliteal diameter was > or = 1.5, in relation to cardiovascular and genetic risk factors.

RESULTS

Clinical examination detected popliteal aneurysms in only 11/232 patients (5%), but ultrasonography demonstrated the presence of popliteal aneurysm in a further 13 patients, 24/232 in total (10%). Multivariate regression identified four independent factors associated with popliteal dilatation disease: age (p = 0.046), height (p = 0.006), systolic hypertension (p = 0.037) and triglyceride concentration (p = 0.009). Generalised aneurysmal disease and systolic blood pressure were associated with polymorphic variation in the fibrillin-1 gene, but not with variations in the apolipoprotein B and type III collagen genes.

CONCLUSIONS

Few patients with abdominal aortic aneurysm (10%) also have popliteal aneurysms: the risk of popliteal dilatation increases with age, height, systolic blood pressure, triglyceride concentration and fibrillin genotype. The strong interaction between fibrillin genotype and blood pressure may contribute to the familial tendency to aortic aneurysm.