Uric acid and risk of pre-eclampsia: results from a large case-control study and meta-analysis of prospective studies.

To quantify the association between maternal uric acid levels and pre-eclampsia risk in a large collection of primigravid women. A case-control study (1365 cases of pre-eclampsia and 1886 normotensive controls) was conducted. Pre-eclampsia was defined as blood pressure ≥ 140/90 mmHg and proteinuria ≥ 300 mg/24 h. Sub-outcome analysis included early, intermediate, and late pre-eclampsia. Multivariable analysis for pre-eclampsia and its sub-outcomes was conducted using binary and multinomial logistic regression, respectively. Additionally, a systematic review and meta-analysis of cohort studies measuring uric acid levels < 20 weeks of gestation was performed to rule out reverse causation. There was a positive linear association between increasing uric acid levels and presence of pre-eclampsia. Adjusted odds ratio of pre-eclampsia was 1.21 (95%CI 1.11-1.33) for every one standard deviation increase in uric acid levels. No differences in the magnitude of association were observed between early and late pre-eclampsia. Three studies with uric acid measured < 20 weeks' gestation were identified, with a pooled OR for pre-eclampsia of 1.46 (95%CI 1.22-1.75) for a top vs. bottom quartile comparison. Maternal uric acid levels are associated with risk of pre-eclampsia. Mendelian randomisation studies would be helpful to further explore the causal role of uric acid in pre-eclampsia.

C-reactive protein, interleukin-6 and pre-eclampsia: large-scale evidence from the GenPE case-control study.

Multiple small studies have suggested that women with pre-eclampsia present elevated levels of C-reactive protein (CRP) and interleukin-6 (IL-6). However, little is known regarding the source of this CRP and IL-6 increase. Therefore, the aim of this study was to evaluate the relationship between CRP and IL-6 levels with pre-eclampsia considering different confounding factors. Using data from a large Colombian case-control study (3,590 cases of pre-eclampsia and 4,564 normotensive controls), CRP and IL-6 levels were measured in 914 cases and 1297 controls. The association between maternal serum levels of CRP and IL-6 with pre-eclampsia risk was evaluated using adjusted logistic regression models. Pre-eclampsia was defined as presence of blood pressure ≥140/90 mmHg and proteinuria ≥300mg/24 h (or ≥1 + dipstick). There was no evidence of association between high levels of CRP and IL-6 with pre-eclampsia after adjusting for the following factors: maternal and gestational age, ethnicity, place and year of recruitment, multiple-pregnancy, socio-economic position, smoking, and presence of infections during pregnancy. The adjusted OR for 1SD increase in log-CRP and log-IL-6 was 0.96 (95%CI 0.85, 1.08) and 1.09 (95%CI 0.97, 1.22), respectively. Although previous reports have suggested an association between high CRP and IL-6 levels with pre-eclampsia, sample size may lack the sufficient power to draw robust conclusions, and this association is likely to be explained by unaccounted biases. Our results, the largest case-control study reported up to date, demonstrate that there is not a causal association between elevated levels of CRP and IL-6 and the presence of pre-eclampsia.

Association of pre-eclampsia risk with maternal levels of folate, homocysteine and vitamin B12 in Colombia: A case-control study.

BACKGROUND: Maternal serum concentrations of folate, homocysteine, and vitamin B12 have been associated with pre-eclampsia. Nevertheless, reported studies involve limited number of cases to reliably assess the nature of these associations. Our aim was to examine the relation of these three biomarkers with pre-eclampsia risk in a large Colombian population. MATERIALS AND METHODS: Design: A case-control study. Setting: Cases of pre-eclampsia and healthy pregnant controls were recruited at the time of delivery from eight different Colombian cities between 2000 and 2012. Population or Sample: 2978 cases and 4096 controls were studied. Maternal serum concentrations of folate, homocysteine, and vitamin B12 were determined in 1148 (43.6%) cases and 1300 (31.7%) controls. Also, self-reported folic acid supplementation was recorded for 2563 (84%) cases and 3155 (84%) controls. Analysis: Adjusted odds ratios (OR) for pre-eclampsia were estimated for one standard deviation (1SD) increase in log-transformed biomarkers. Furthermore, we conducted analyses to compare women that reported taking folic acid supplementation for different periods during pregnancy. Main Outcomes Measures: Odds ratio for pre-eclampsia. RESULTS: After adjusting for potential confounders in logistic regression models, the OR for pre-eclampsia was 0.80 (95% CI: 0.72, 0.90) for 1SD increase in log-folate, 1.16 (95%CI: 1.05, 1.27) for 1SD increase in log-homocysteine, and 1.10 (95%CI: 0.99, 1.22) for 1SD increase in log-vitamin B12. No interactions among the biomarkers were identified. Women who self-reported consumption of folic acid (1 mg/day) throughout their pregnancy had an adjusted OR for pre-eclampsia of 0.86 (95%CI: 0.67, 1.09) compared to women that reported no consumption of folic acid at any point during pregnancy. CONCLUSIONS: Maternal serum concentrations of folate were associated as a protective factor for pre-eclampsia while concentrations of homocysteine were associated as a risk factor. No association between maternal vitamin B12 concentrations and preeclampsia was found.

Lipid profile, plasma apolipoproteins, and pre-eclampsia risk in the GenPE case-control study.

BACKGROUND AND AIMS: Pre-eclampsia constitutes a leading cause of maternal and perinatal morbidity and mortality. Pre-eclampsia susceptibility is believed to be associated with altered lipid profiles and abnormal lipid metabolism via lipid peroxidation that leads to endothelial dysfunction. The goal of this study was to evaluate the association of maternal blood lipid and apolipoprotein levels with pre-eclampsia in a large-scale study. METHODS: Using data from a large case-control study (1366 cases of pre-eclampsia and 1741 normotensive controls), the association between the distributions of eight lipid fractions and pre-eclampsia risk was evaluated using adjusted logistic regression models. Pre-eclampsia was defined as blood pressure ≥140/90 mmHg and proteinuria ≥300 mg/24 h (>1 + dipstick). Sub-group analyses were conducted for early (<34 weeks) and late (≥37 weeks) pre-eclampsia, estimating the effect of 1 standard deviation increase in log-transformed lipid fraction levels in adjusted multinomial regression models. RESULTS: After adjustment for potential confounders, concentrations of triglycerides, apolipoprotein E (ApoE) and the relationship between apolipoprotein B and A1 (ApoB/ApoA1) showed the strongest associations with pre-eclampsia, particularly for those cases with an early onset. CONCLUSIONS: Higher levels of triglycerides, ApoE and the ApoB/ApoA1 ratio are associated with an increased risk of pre-eclampsia. Further studies that allow for a causal inference are needed to confirm or refute the aetiological role of blood lipids in pre-eclampsia.

Circunferencia de cintura, perfil de lípidos y riesgo cardiovascular en adolescentes / Waist circumference, lipid profile and cardiovascular risk in adolescents

La obesidad abdominal y las dislipidemias son factores de riesgo de enfermedad cardiovascular (ECV). Se evaluó la relación de la circunferencia de cintura (CC), con los lípidos e índices de riesgo cardiovascular en 414 adolescentes (12-16,9 años). El estudio fue descriptivo, correlacional, transversal, y de campo. Se midió: peso, talla, CC y se calculó el índice de masa corporal (IMC). Se determinó colesterol total (CT), triglicéridos (TG) y lipoproteína de alta densidad (HDL-c). Se calculó: la lipoproteína de baja densidad (LDL-c), el colesterol no-HDL y las relaciones de riesgo aterogénico. Se realizaron estadísticos descriptivos, las pruebas de Mann Whitney, Chi cuadrado y Odds Ratio, con significancia estadística de p<0,05. 18,1% y 7,0% presentaron sobrepeso y obesidad, respectivamente y 38,9% tenían CC≥p90. Los adolescentes con CC≥p90 mostraron cifras más elevadas de peso, IMC y de CT, colesterol no-HDL, TG y de los índices CT/HDL-C y TG/HDL-C que los adolescentes con CC

Abdominal obesity and dyslipidemias have been considered cardiovascular risk factors. This descriptive and cross-sectional study was undertaken to assess the relationship between waist circumference (WC) and lipid profile, and Cardiovascular risk factors in 414 adolescents (ages 12 to16.9 years). Height, weight and WC were measured and body mass index was (BMI) estimated. Plasma levels for triglycerides, total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C) were determined. Low-density lipoprotein cholesterol (LDL-C) and non-HDL-C and atherogenic risk index were assessed. Mann-Whitney, Odds Ratio and Chi-square test were calculated and significance level p<0.05 was considered. 18.1% and 7% presented overweight and obesity, respectively and 38.9% had WC equal or greater than the 90th percentile (WC≥p90). Significant higher levels (p<0.05) for weight, IMC, TC, TG, non-HDL, TC/HDL-C index and TG/HDL-C Index were found in adolescents with WC≥p90. Males had higher mean values for weight, height, BMI and WC than females (p<0.05). Females had higher TC, HDL-C and LDL-C concentrations than males (p<0.05). Adolescents with WC≥p90 are more likely to have a higher atherogenic risk index than those with WC

Genetic association studies in pre-eclampsia: systematic meta-analyses and field synopsis.

BACKGROUND: Pre-eclampsia is thought to have a polygenic basis, but the identification of susceptibility genes and the quantification of associated risks have been elusive owing to lack of replication from published genetic association studies. OBJECTIVE: To perform a systematic review and meta-analysis of genetic association studies to evaluate the evidence for the associations of various candidate genes with pre-eclampsia. METHODS: For inclusion, studies had to involve unrelated subjects and examine the associations between pre-eclampsia (excluding publications without a measurement of proteinuria) and any candidate variant. Authors were contacted to obtain unpublished data when necessary. A meta-analysis was conducted for all variants with three or more independent samples available. Summary odds ratios (ORs), 99% confidence intervals (CIs) and P-values were calculated using random effects models. RESULTS: Data from 192 genetic association studies met the selection criteria and were included in 25 independent meta-analyses. There was some evidence of association for F5 rs6025 (OR = 1.74; 99% CI 1.43-2.12), F2 rs1799963 (OR = 1.72; 99% CI 1.31-2.26), ACE rs4646994 (OR = 1.17; 99% CI 0.99-1.40), AGT rs699 (OR = 1.26; 99% CI 1.00-1.59) and AGTR1 rs5186 (OR = 1.22; 99% CI 0.96-1.56), but only the first two associations reached moderate epidemiological credibility. Possible bias resulting from small study size and poor reporting of individual studies were the most important factors affecting the reported associations. CONCLUSION: To date, candidate gene studies in pre-eclampsia have not robustly documented any associations with strong epidemiological credibility. Large-scale replication of the most promising associations, exhibited by two genetic variants, and incorporation of agnostic high-throughput data may improve our genetic knowledge base for this complex phenotype.

Analysis of population genetic structure from Bucaramanga (Colombia) based on gene polymorphisms associated with regulation of blood pressure / Análisis de la estructura genética poblacional a partir de polimorfismos de genes asociados con la regulación de la presión arterial en una muestra de Bucaramanga, Colombia

Introduction: In spite nearly 40% of the variability in blood pressure can be explained by genetic factors, the identification of genes associated to essential high blood pressure is difficult in populations where individuals have different genetic precedents; in these circumstances it is necessary to determinate whether the population is sub-structured because this can bias studies associated with this disease.Objectives: To determine the genetic structure of the population in Bucaramanga from genetic polymorphisms associated with the regulation of blood pressure: 448G>T, 679C>T y 1711C>T from the gene kinase 4 of the dopaminergic receptor linked to the protein G and Glu298Asp, -786T>C and the VNTR of the intron 4 of the gene of endothelial nitric oxide.Methodology: A sample of 552 unrelated individuals was studied through analysis of Restriction fragment length polymorphism. The allelic, haplotypic and genotypic frequencies were calculated, the Hardy-Weinberg equilibrium was determined and a molecular analysis of variance was performed to determine the genetic structure.Results: 38 Haplotypes were identified, with GCCTG4b as the most frequent (21.2%). The most diverse polymorphism was 448G>T with a frequency of 49.9% for heterozygous. The six polymorphisms were found in genetic equilibrium and genetic structure of populations was not evidenced (FST = 0,0038).Conclusion: The population studied does not present a genetic sub-structure and the polymorphisms analyzed were found in genetic equilibrium, this indicates that the population mixes randomly and there are no sub-groups capable of affecting the results of the association studies

Analysis of population genetic structure from Bucaramanga (Colombia) based on gene polymorphisms associated with the regulation of blood pressure.

INTRODUCTION: In spite of nearly 40% of variability in blood pressure being explained by genetic factors, the identification of genes associated with essential high blood pressure is difficult to determine in populations where individuals have different genetic backgrounds. In these circumstances it is necessary to determinate whether the population is sub-structured because this can bias studies associated with this disease. OBJECTIVE: TO DETERMINE THE GENETIC STRUCTURE OF THE POPULATION IN BUCARAMANGA FROM GENETIC POLYMORPHISMS ASSOCIATED WITH THE REGULATION OF BLOOD PRESSURE: 448G>T, 679C>T y 1711C>T from the gene kinase 4 of the dopaminergic receptor linked to the protein G and Glu298Asp, -786T>C and the VNTR of the intron 4 of the gene of endothelial nitric oxide. METHODS: A sample of 552 unrelated individuals was studied through analysis of restriction fragment length polymorphism. The allelic, haplotypic and genotypic frequencies were calculated, the Hardy-Weinberg equilibrium was determined and a molecular analysis of variance was performed to determine the genetic structure. RESULTS: Thirty-eight (38) Haplotypes were identified with GCCTG4b being the most frequent (21.2%). The most diverse polymorphism was 448G>T with a frequency of 49.9% for heterozygous. The six polymorphisms were found in genetic equilibrium and a genetic structure of populations was not evidenced (FST= 0.0038). CONCLUSION: The population studied does not present a genetic sub-structure and the polymorphisms analyzed were found in genetic equilibrium. This indicates that the population mixes randomly and there are no sub-groups capable of affecting the results of the association studies.

INTRODUCCIÓN: A pesar que cerca del 40% de la variabilidad en la presión arterial es explicada por factores genéticos, la identificación de genes asociados a la hipertensión arterial esencial es difícil en poblaciones constituidas por individuos con antecedentes genéticos diferentes; en esta circunstancia se debe determinar si la población está sub-estructurada porque esto puede sesgar los estudios de asociación con esta enfermedad. OBJETIVO: Determinar la estructura genética de la población de Bucaramanga a partir de polimorfismos genéticos asociados con la regulación de la presión arterial: 448G>T, 679C>T y 1711C>T del gen de la quinasa 4 del receptor dopaminérgico acoplado a proteína G y Glu298Asp, -786T>C y el VNTR del intrón 4 del gen de la sintasa de óxido nítrico endotelial. MÉTODOS: Se estudió una muestra de 552 individuos no relacionados mediante análisis de polimorfismos de longitud de fragmentos de restricción. Se calcularon las frecuencias alélicas, haplotípicas y genotípicas, se determinó el equilibrio de Hardy-Weinberg y se realizó un análisis molecular de varianza para determinar la estructura genética. RESULTADOS: Se identificaron 38 haplotipos siendo GCCTG4b el más frecuente (21.2%). El polimorfismo más diverso fue el 448G>T con una frecuencia de heterocigotos del 49.9%. Los seis polimorfismos se encontraron en equilibrio genético y no se evidenció estructura genética poblacional (FST = 0.0038). CONCLUSIÓN: La población estudiada no presenta subestructura genética y los polimorfismos analizados se encontraron en equilibrio genético, lo que indica que la población se mezcla aleatoriamente y no existen subgrupos que puedan afectar los resultados de estudios de asociación.

Frequency of eNOS polymorphisms in the Colombian general population.

BACKGROUND: Nitric oxide (NO) synthesized by endothelial cells is known to be a potent vasodilator. It has been suggested that polymorphisms in endothelial nitric oxide synthase (eNOS) can affect the response of the vascular endothelium to increased oxidative stress. The objective of the present study was to determine the presence of G894T (rs1799983), intron-4 (27-bp TR) and -T786C (rs2070744) polymorphisms in the eNOS gene among the Colombian general population. RESULTS: Genotype and allele frequencies showed significant differences in their distribution. White, black and mixed populations were in HW equilibrium for the variants in 27-bp TR- and rs1799983, but the black population was in HW disequilibrium for rs2070744 (p < 0.001). Allele "T" of rs1799983 polymorphisms was more common in the white population (26,5%) than the others, while allele "C" of rs2070744 polymorphisms had a similar frequency in all populations, and the allele 4a from 27-bp TR was more frequent in the black population (26,2%) than the others. Similar differences were found when genotypes were analyzed. CONCLUSION: The findings suggest that there is a substantial difference in the distribution of eNOS polymorphisms between different ethnic groups. These results could aid the understanding of inter-ethnic differences in NO bioavailability, cardiovascular risk, and response to drugs.

Angiotensin-converting enzyme I/D polymorphism and preeclampsia risk: evidence of small-study bias.

BACKGROUND: Inappropriate activation of the renin-angiotensin system may play a part in the development of preeclampsia. An insertion/deletion polymorphism within the angiotensin-I converting enzyme gene (ACE-I/D) has shown to be reliably associated with differences in angiotensin-converting enzyme (ACE) activity. However, previous studies of the ACE-I/D variant and preeclampsia have been individually underpowered to detect plausible genotypic risks. METHODS AND FINDINGS: A prospective case-control study was conducted in 1,711 unrelated young pregnant women (665 preeclamptic and 1,046 healthy pregnant controls) recruited from five Colombian cities. Maternal blood was obtained to genotype for the ACE-I/D polymorphism. Crude and adjusted odds ratio (OR) and 95% confidence interval (CI) using logistic regression models were obtained to evaluate the strength of the association between ACE-I/D variant and preeclampsia risk. A meta-analysis was then undertaken of all published studies to February 2006 evaluating the ACE-I/D variant in preeclampsia. An additive model (per-D-allele) revealed a null association between the ACE-I/D variant and preeclampsia risk (crude OR = 0.95 [95% CI, 0.81-1.10]) in the new case-control study. Similar results were obtained after adjusting for confounders (adjusted per-allele OR = 0.90 [95% CI, 0.77-1.06]) and using other genetic models of inheritance. A meta-analysis (2,596 cases and 3,828 controls from 22 studies) showed a per-allele OR of 1.26 (95% CI, 1.07-1.49). An analysis stratified by study size showed an attenuated OR toward the null as study size increased. CONCLUSIONS: It is highly likely that the observed small nominal increase in risk of preeclampsia associated with the ACE D-allele is due to small-study bias, similar to that observed in cardiovascular disease. Reliable assessment of the origins of preeclampsia using a genetic approach may require the establishment of a collaborating consortium to generate a dataset of adequate size.