Familial aggregation of blood pressure, anthropometric characteristics and urinary excretion of sodium and potassium--a population study in two Belgian towns

Evidence of correlations between human partners based on systematic reviews and meta-analyses of 22 traits and UK Biobank analysis of 133 traits

Positive correlations between mates can increase trait variation and prevalence, as well as bias estimates from genetically informed study designs. While past studies of similarity between human mating partners have largely found evidence of positive correlations, to our knowledge, no formal meta-analysis has examined human partner correlations across multiple categories of traits. Thus, we conducted systematic reviews and random-effects meta-analyses of human male-female partner correlations across 22 traits commonly studied by psychologists, economists, sociologists, anthropologists, epidemiologists and geneticists. Using ScienceDirect, PubMed and Google Scholar, we incorporated 480 partner correlations from 199 peer-reviewed studies of co-parents, engaged pairs, married pairs and/or cohabitating pairs that were published on or before 16 August 2022. We also calculated 133 trait correlations using up to 79,074 male-female couples in the UK Biobank (UKB). Estimates of the 22 mean meta-analysed correlations ranged from rmeta = 0.08 (adjusted 95% CI = 0.03, 0.13) for extraversion to rmeta = 0.58 (adjusted 95% CI = 0.50, 0.64) for political values, with funnel plots showing little evidence of publication bias across traits. The 133 UKB correlations ranged from rUKB = -0.18 (adjusted 95% CI = -0.20, -0.16) for chronotype (being a 'morning' or 'evening' person) to rUKB = 0.87 (adjusted 95% CI = 0.86, 0.87) for birth year. Across analyses, political and religious attitudes, educational attainment and some substance use traits showed the highest correlations, while psychological (that is, psychiatric/personality) and anthropometric traits generally yielded lower but positive correlations. We observed high levels of between-sample heterogeneity for most meta-analysed traits, probably because of both systematic differences between samples and true differences in partner correlations across populations.

Blood pressure and cardiovascular risk in relation to birth weight and urinary sodium: an individual-participant meta-analysis of European family-based population studies

BACKGROUND

Although the relation of salt intake with blood pressure (BP) is linear, it is U-shaped for mortality and cardiovascular disease (CVD). This individual-participant meta-analysis explored whether the relation of hypertension, death or CVD with 24-h urinary sodium excretion (UVNA) or sodium-to-potassium (UNAK) ratio was modified by birth weight.

METHODS

Families were randomly enrolled in the Flemish Study on Genes, Environment and Health Outcomes (1985-2004) and the European Project on Genes in Hypertension (1999-2001). Categories of birth weight, UVNA and UNAK (≤2500, >2500-4000, >4000 g; <2.3, 2.3-4.6 and >4.6 g; and <1, 1-2, >2, respectively) were coded using deviation-from-mean coding and analyzed by Kaplan-Meier survival functions and linear and Cox regression.

RESULTS

The study population was subdivided into the Outcome ( n  = 1945), Hypertension ( n  = 1460) and Blood Pressure cohorts ( n  = 1039) to analyze the incidence of mortality and cardiovascular endpoints, hypertension and BP changes as function of UVNA changes. The prevalence of low/medium/high birth weight in the Outcome cohort was 5.8/84.5/9.7%. Over 16.7 years (median), rates were 4.9, 8 and 27.1% for mortality, CVD and hypertension, respectively, but were not associated with birth weight. Multivariable-adjusted hazard ratios were not significant for any endpoint in any of the birth weight, UVNA and UNAK strata. Adult body weight tracked with birth weight ( P  < 0.0001). The partial r in the low-birth-weight group associating changes from baseline to follow-up in UVNA and SBP was 0.68 ( P  = 0.023) but not significant in other birth weight groups.

CONCLUSION

This study did not substantiate its prior hypothesis but showed tracking of adult with birth weight and suggest that low birth weight increases salt sensitivity.

Conventional and Ambulatory Blood Pressure as Predictors of Diastolic Left Ventricular Function in a Flemish Population

Background

No longitudinal study compared associations of echocardiographic indexes of diastolic left ventricular function studies with conventional (CBP) and daytime ambulatory (ABP) blood pressure in the general population.

Methods and Results

In 780 Flemish (mean age, 50.2 years; 51.7% women), we measured left atrial volume index (LAVI), peak velocities of the transmitral blood flow (E) and mitral annular movement (e′) in early diastole and E/e′ 9.6 years (median) after CBP and ABP. In adjusted models including CBP and ABP, we expressed associations per 10/5‐mm Hg systolic/diastolic blood pressure increments. LAVI and E/e′ were 0.65/0.40 mL/m² and 0.17/0.09 greater with higher systolic/diastolic ABP (P≤0.028), but not with higher baseline CBP (P≥0.086). e′ was lower (P≤0.032) with higher diastolic CBP (−0.09 cm/s) and ABP (−0.19 cm/s). When we substituted baseline CBP by CBP recorded concurrently with echocardiography, LAVI and E/e′ remained 0.45/0.38 mL/m² and 0.15/0.08 greater with baseline ABP (P≤0.036), while LAVI (+0.53 mL/m²) and E/e′ (+0.19) were also greater (P<0.001) in relation to concurrent systolic CBP. In categorized analyses of baseline data, sustained hypertension or masked hypertension compared with normotension or white‐coat hypertension was associated with greater LAVI (24.0 versus 22.6 mL/m²) and E/e′ (7.35 versus 6.91) and lower e′ (10.7 versus 11.6 cm/s; P≤0.006 for all) with no differences (P≥0.092) between normotension and white‐coat hypertension or between masked hypertension and sustained hypertension.

Conclusions

ABP is a long‐term predictor of diastolic left ventricular function, statistically outperforming distant but not concurrent CBP. Masked hypertension and sustained hypertension carry equal risk for deterioration of diastolic left ventricular function.

Assortative mating for human height: A meta-analysis

OBJECTIVES

The study of assortative mating for height has a rich history in human biology. Although the positive correlation between the stature of spouses has often been noted in western populations, recent papers suggest that mating patterns for stature are not universal. The objective of this paper was to review the published evidence to examine the strength of and universality in assortative mating for height.

METHODS

We conducted an extensive literature review and meta-analysis. We started with published reviews but also searched through secondary databases. Our search led to 154 correlations of height between partners. We classified the populations as western and non-western based on geography. These correlations were then analyzed via meta-analytic techniques.

RESULTS

148 of the correlations for partner heights were positive and the overall analysis indicates moderate positive assortative mating (r = .23). Although assortative mating was slightly stronger in countries that can be described as western compared to non-western, this difference was not statistically significant. We found no evidence for a change in assortative mating for height over time. There was substantial residual heterogeneity in effect sizes and this heterogeneity was most pronounced in western countries.

CONCLUSIONS

Positive assortative mating for height exists in human populations, but is modest in magnitude suggesting that height is not a major factor in mate choice. Future research is necessary to understand the underlying causes of the large amount of heterogeneity observed in the degree of assortative mating across human populations, which may stem from a combination of methodological and ecological differences.

Conventional and Ambulatory Blood Pressure as Predictors of Retinal Arteriolar Narrowing

Supplemental Digital Content is available in the text.

At variance with the long established paradigm that retinal arteriolar narrowing trails hypertension, several longitudinal studies, all based on conventional blood pressure (CBP) measurement, proposed that retinal arteriolar narrowing indicates heightened microvascular resistance and precedes hypertension. In 783 randomly recruited Flemish (mean age, 38.2 years; 51.3% women), we investigated to what extent CBP and daytime (10 am to 8 pm) ambulatory blood pressure (ABP) measured at baseline (1989–2008) predicted the central retinal arteriolar equivalent (CRAE) in retinal photographs obtained at follow-up (2008–2015). Systolic/diastolic hypertension thresholds were 140/90 mm Hg for CBP and 135/85 mm Hg for ABP. In multivariable-adjusted models including both baseline CBP and ABP, CRAE after 10.3 years (median) of follow-up was unrelated to CBP (P≥0.14), whereas ABP predicted CRAE narrowing (P≤0.011). Per 1-SD increment in systolic/diastolic blood pressure, the association sizes were −0.95 µm (95% confidence interval, −2.20 to 0.30)/−0.75 µm (−1.93 to 0.42) for CBP and −1.76 µm (−2.95 to −0.58)/−1.48 µm (−2.61 to −0.34) for ABP. Patients with ambulatory hypertension at baseline (17.0%) had smaller CRAE (146.5 versus 152.6 µm; P<0.001) at follow-up. CRAE was not different (P≥0.31) between true normotension (normal CBP and ABP; prevalence, 77.6%) and white-coat hypertension (elevated CBP and normal ABP, 5.4%) and between masked hypertension (normal CBP and elevated ABP, 10.2%) and hypertension (elevated CBP and ABP, 6.8%). In conclusion, the paradigm that retinal arteriolar narrowing precedes hypertension can be explained by the limitations of CBP measurement, including nonidentification of masked and white-coat hypertension.

Urinary Proteomics Pilot Study for Biomarker Discovery and Diagnosis in Heart Failure with Reduced Ejection Fraction

Background

Biomarker discovery and new insights into the pathophysiology of heart failure with reduced ejection fraction (HFrEF) may emerge from recent advances in high-throughput urinary proteomics. This could lead to improved diagnosis, risk stratification and management of HFrEF.

Methods and Results

Urine samples were analyzed by on-line capillary electrophoresis coupled to electrospray ionization micro time-of-flight mass spectrometry (CE-MS) to generate individual urinary proteome profiles. In an initial biomarker discovery cohort, analysis of urinary proteome profiles from 33 HFrEF patients and 29 age- and sex-matched individuals without HFrEF resulted in identification of 103 peptides that were significantly differentially excreted in HFrEF. These 103 peptides were used to establish the support vector machine-based HFrEF classifier HFrEF103. In a subsequent validation cohort, HFrEF103 very accurately (area under the curve, AUC = 0.972) discriminated between HFrEF patients (N = 94, sensitivity = 93.6%) and control individuals with and without impaired renal function and hypertension (N = 552, specificity = 92.9%). Interestingly, HFrEF103 showed low sensitivity (12.6%) in individuals with diastolic left ventricular dysfunction (N = 176). The HFrEF-related peptide biomarkers mainly included fragments of fibrillar type I and III collagen but also, e.g., of fibrinogen beta and alpha-1-antitrypsin.

Conclusion

CE-MS based urine proteome analysis served as a sensitive tool to determine a vast array of HFrEF-related urinary peptide biomarkers which might help improving our understanding and diagnosis of heart failure.

Nigerian Population Research on Environment, Gene and Health (NIPREGH) - objectives and protocol

Sub-Saharan Africa is currently undergoing an epidemiological transition from a disease burden largely attributable to communicable diseases to that resulting from a combination of both communicable and chronic non-communicable diseases. Data on chronic disease incidence, lifestyle, environmental and genetic risk factors are sparse in this region. This report aimed at providing relevant information in respect to risk factors that increase blood pressure and lead to development of intermediate cardiovascular phenotypes. We presented the rationale, objectives and key methodological features of the Nigerian Population Research on Environment, Gene and Health (NIPREGH) study. The challenges encountered in carrying out population study in this part of the world and the approaches at surmounting them were also presented. The preliminary data as at 20 November 2013 showed that out of the 205 individuals invited starting from early April 2013, 160 (72 women) consented and were enrolled; giving a response rate of 78%. Participants' age ranged from 18 to 80 years, with a mean (SD) of 39.8 (12.4) years and they were of 34 different ethnic groups spread over 24 states out of the 36 states that constitute Nigeria. The mean (SD) of office and home blood pressures were 113.0 (15.2) mm Hg systolic, 73.5 (12.5) mm Hg diastolic and 117.3 (15.0) mm Hg systolic, and 76.0 (9.6) mm Hg diastolic, respectively. Forty-three (26.8%) participants were hypertensive and 8 (5.0%) were diabetic. In addition to having the unique potential of recruiting a cohort that is a true representative of the entire Nigerian population, NIPREGH is feasible and the objectives realisable.

Heritability of the retinal microcirculation in Flemish families

BACKGROUND

Few population studies have described the heritability and intrafamilial concordance of the retinal microvessels, or the genetic or environmental correlations of the phenotypes of these vessels.

METHODS

We randomly selected 413 participants from 70 families (mean age, 51.5 years; 50.1% women) from a Flemish population. We postprocessed retinal images using IVAN software to generate the central retinal arteriole equivalent (CRAE), central retinal venule equivalent (CRVE), and arteriole-to-venule-ratio (AVR) from these images. We used SAGE version 6.2 and SAS version 9.2 to compute multivariate-adjusted estimates of heritability and intrafamilial correlations of the CRAE, CRVE, and AVR of the retinal microvessels in the images.

RESULTS

Sex, age, mean arterial pressure, and smoking explained up to 12.7% of the variance of the phenotypes of the retinal microvessels of the study participants. With adjustments applied for these covariates, the heritability estimates of CRAE, CRVE, and AVR were 0.213 (P = 0.044), 0.339 (P = 0.010), and 0.272 (P = 0.004), respectively. The parent-offspring correlations for CRAE, CRVE, and AVR were 0.118 (NS), 0.225 (P < 0.01), and 0.215 (P < 0.05), respectively. The corresponding values were 0.222 (P < 0.05), 0.213 (P < 0.05), and 0.390 (P < 0.001) for sib-sib correlations, respectively. The genetic and environmental correlations between CRAE and CRVE were 0.360 and 0.545 (P < 0.001 for both).

CONCLUSION

Our study showed moderate heritability for CRAE, CRVE, and AVR, and a significant genetic correlation of CRAE with CRVE in the Flemish population of our study. These findings suggest that genetic factors influence the diameter of the retinal microvessels, and that CRAE and CRVE share some genetic determinants.

Within-subject blood pressure level--not variability--predicts fatal and nonfatal outcomes in a general population

To assess the prognostic significance of blood pressure (BP) variability, we followed health outcomes in a family-based random population sample representative of the general population (n=2944; mean age: 44.9 years; 50.7% women). At baseline, BP was measured 5 times consecutively at each of 2 home visits 2 to 4 weeks apart. We assessed within-subject overall (10 readings), within- and between-visit systolic BP variability from variability independent of the mean, the difference between maximum and minimum BP, and average real variability. Over a median follow-up of 12 years, 401 deaths occurred and 311 participants experienced a fatal or nonfatal cardiovascular event. Overall systolic BP variability averaged (SD) 5.45 (2.82) units, 15.87 (8.36) mmHg, and 4.08 (2.05) mmHg for variability independent of the mean, difference between maximum and minimum BP, and average real variability, respectively. Female sex, older age, higher-mean systolic BP, lower body mass index, a history of peripheral arterial disease, and use of β-blockers were the main correlates of systolic BP variability. In multivariable-adjusted analyses, overall and within- and between-visit BP variability did not predict total or cardiovascular mortality or the composite of any fatal plus nonfatal cardiovascular end point. For instance, the hazard ratios for all cardiovascular events combined in relation to overall variability independent of the mean, difference between maximum and minimum BP, and average real variability were 1.05 (0.96-1.15), 1.06 (0.96-1.16), and 1.08 (0.98-1.19), respectively. By contrast, mean systolic BP was a significant predictor of all end points under study, independent of BP variability. In conclusion, in an unbiased population sample, BP variability did not contribute to risk stratification over and beyond mean systolic BP.

Sphygmomanometric and ambulatory blood pressures as forerunners of carotid and femoral intima-media thickness

OBJECTIVE

Studies directly comparing the associations of intima-media thickness with blood pressure (BP) on manual sphygmomanometric blood pressure measurement (SBPM) and 24-h ambulatory blood pressure measurement (ABPM) are scarce and have a cross-sectional design.

METHODS

At baseline, we measured systolic and diastolic blood pressures, pulse pressure, and mean arterial pressure in 532 randomly recruited patients (women, 48.3%; mean age, 38.9 years) by SBPM and ABPM. SBPM was the average of five consecutive readings obtained by trained observers at the patients' homes. We measured carotid intima-media thickness (CIMT) and femoral intima-media thickness (FIMT) by a wall-tracking ultrasound system, 26 months (median) after BP measurement (interquartile range, 21-29 months). We adjusted all analyses for observer, sex, age, BMI, smoking, and total/high-density lipoprotein-cholesterol ratio.

RESULTS

The multivariable-adjusted associations of CIMT and FIMT with all BP components on SBPM were not significant (P >or= 0.12). In multivariable-adjusted models, CIMT increased with 24-h systolic blood pressure (effect size per SD increase, +0.131 mm; P = 0.003) and 24-h pulse pressure (+0.139 mm; P = 0.001), whereas FIMT increased with 24-h diastolic blood pressure (+0.091 mm; P = 0.03) and 24-h mean arterial pressure (+0.090 mm; P = 0.04). Models including the ambulatory blood pressure components additionally adjusted for SBPM and more covariables than those listed above were confirmatory.

CONCLUSION

In a general population, BP on ABPM predicts CIMT and FIMT over and beyond highly standardized SBPM. At the elastic carotid artery, CIMT increased predominantly with the pulsatile component of BP, whereas at the muscular femoral artery, FIMT increased with the steady component of BP.

Conventional and 24-h ambulatory blood pressure as independent predictors of elastic arterial properties

OBJECTIVE

No population study investigated whether 24-h ambulatory blood pressure (ABP) predicts distensibility of the elastic common carotid (DCar) and the muscular femoral (DFem) arteries over and beyond conventionally measured blood pressure (CBP).

METHODS

At baseline, we measured CBP and 24-h ABP in 1063 randomly recruited participants (mean age, 44.3 years). CBP was the average of five consecutive readings obtained by trained observers at the participants' homes. We measured arterial distensibility by a wall-tracking ultrasound system, 21 months after CBP and ABP (5-95th percentile interval range, 13-33 months).

RESULTS

Compared with men, women (49.2%) had higher (P<0.03) DCar (24.7 vs. 23.3 x 10(-3)/kPa) and higher DFem (10.6 vs. 9.2 x 10(-3)/kPa). In multivariate-adjusted models, including both CBP and ABP and stratified by sex, DCar was negatively related to systolic, diastolic, and mean arterial CBP in both sexes, and to diastolic ABP in women. DFem was inversely correlated with diastolic ABP in both sexes and with systolic and mean arterial ABP in men. Moreover, DFem was also negatively correlated with systolic and mean arterial CBP in men. In most instances, pulse pressure on CBP or ABP measurement did not predict DCar or DFem. No evidence of influential collinearity between CBP and ABP was observed.

CONCLUSION

Depending on vascular territory, there is competition between highly standardized CBP and ABP in predicting DCar and DFem. These findings show that CBP under standardized conditions, and subject to rigorous quality control, is equally predictive of the elastic properties of large arteries as ABP.

Spousal concordance for major coronary risk factors: a systematic review and meta-analysis

Spousal pairs permit assessment of determinants of diseases related to environment, because they share the same lifestyle and environment. The authors reviewed spouses' concordance for the major coronary risk factors. A search of the MEDLINE, PubMed, and EMBASE databases was performed. Seventy-one papers were selected for a total of 207 cohorts of pairs and 424,613 correlations in more than 100,000 couples. The most strongly correlated within-pairs factors were smoking and body mass index, with overall correlations of 0.23 (95% confidence interval: 0.12, 0.36) and 0.15 (95% confidence interval: 0.05, 0.25), respectively. Statistically significant positive correlations were also found for diastolic blood pressure, triglycerides, total and low density lipoprotein cholesterol, weight, and the waist/hip ratio. The overall odds ratios for concordance in hypertension, smoking, diabetes, and obesity were all statistically significant, ranging from 1.16 to 3.25. Assortative mating influenced concordance for blood pressure, smoking, glucose, low density lipoprotein cholesterol, weight, body mass index, and waist circumference. This systematic review shows a statistically significant positive spousal concordance for the majority of main coronary risk factors. However, the strength of the concordance was markedly different among factors and appeared to be quite modest for all of them. Interventions to reduce cardiovascular risk factors should be addressed jointly to both members of a marital couple.

Is "usual" blood pressure a proxy for 24-h ambulatory blood pressure in predicting cardiovascular outcomes?

BACKGROUND

The 24-h ambulatory blood pressure (ABP) is a stronger predictor of cardiovascular disease than conventional blood pressure (CBP), but it remains unclear how it compares with "usual" blood pressure (UBP), estimated after CBP has been corrected for regression dilution bias (RDB).

METHODS

We compared the associations of cardiovascular mortality (n = 50), cardiovascular events (n = 101), and cardiac events (n = 71) with systolic CBP, UBP, and ABP over 13 years of follow-up (median) in 1,167 randomly selected Belgians. We estimated the correction factor to compute UBP from CBP at the midpoint of follow-up (6.5 years) in 723 untreated individuals without cardiovascular disease.

RESULTS

Cardiovascular disease increased across quartiles of systolic CBP, UBP, and ABP (P for trend < or =0.02). For each 10 mm Hg increment in systolic ABP, the multivariate-adjusted hazard ratios for cardiovascular mortality and for cardiovascular and cardiac events were 1.38, 1.27, and 1.33, respectively (P < 0.001 for all). For CBP, the corresponding hazard ratios were 1.10 (P = 0.21), 1.09 (P = 0.12), and 1.14 (P = 0.06); and for UBP, they were 1.18 (P = 0.21), 1.16 (P = 0.12), and 1.23 (P = 0.06), respectively. The risk function for cardiovascular disease in relation to ABP was significantly steeper than that for CBP, but not UBP. In Cox models, including CBP or UBP in the presence of ABP, only ABP predicted cardiovascular outcomes.

CONCLUSIONS

Correcting CBP for RDB resulted in a steeper slope of events on blood pressure than observed for CBP. The association with UBP was not statistically significant and did not enhance the prediction of outcome to the level of ABP.

Influence of chorionicity on the heritability estimates of blood pressure: a study in twins

BACKGROUND

A basic assumption of the twin design is that environmental influences including prenatal experiences are equal across twin types. However, the intra-uterine environment may differ according to the chorionicity of the monozygotic twins, which may have biased previous heritability estimates of blood pressure.

OBJECTIVE

The aim of the present study was to assess whether the heritability of blood pressure, derived from measurements in monozygotic and dizygotic twins, differs according to the chorionicity of the monozygotic twins.

METHODS

Conventional and 24-h ambulatory blood pressures were measured in 125 dizygotic twin pairs and in 97 dichorionic and 128 monochorionic monozygotic twin pairs at the age of 18-34 years. The twin sample was drawn from the East Flanders Prospective Twin Survey, in which perinatal data were collected at birth. Intra-pair correlation coefficients were calculated and compared between both types of monozygotic twin pairs. Heritability was estimated from model-fitting and path analysis, based on the dizygotic twins and, respectively, all monozygotic twins and the two subtypes.

RESULTS

Intra-pair correlation coefficients for the various blood pressures, after adjustment for body mass index, ranged from 0.45 to 0.71 in the monozygotic twin pairs and did not differ significantly according to chorionicity. Heritability estimates of blood pressure were between 52 and 64%, and were similar when calculated from dizygotic twins and, respectively, dichorionic and monochorionic monozygotic twins.

CONCLUSIONS

Heritability estimates of conventional and ambulatory blood pressure do not differ significantly according to the chorionicity of the monozygotic twins.

Maternal and paternal influences on left ventricular mass of offspring

Significant intrafamilial correlations of left ventricular mass exist in first-degree relatives. However, the specific maternal and paternal influences on left ventricular mass of offspring remain unknown. We therefore evaluated familial aggregation of left ventricular mass by type of familial relation in two European populations. A random sample of 159 nuclear families (250 parents and 321 offspring) was investigated in Cracow, Poland, and Novosibirsk, Russia. The mean age of parents and offspring was 51.4 years and 25.1 years, respectively. Two-dimensionally guided M-mode echocardiography was performed, and left ventricular mass was calculated. As a measure of concordance, we computed correlation coefficients for left ventricular mass between first-degree relatives and between spouse pairs. After adjustment for center, gender, age, height, body weight, systolic blood pressure, antihypertensive treatment, smoking, alcohol intake, and physical activity, the intrafamilial correlations for left ventricular mass were 0.06 (P=0.57) in 91 spouse-spouse pairs, 0.14 (P=0.002) in 500 parent-offspring pairs, and 0.32 (P<0.001) in 179 sib-sib pairs. Across the four parent-offspring relations, the intrafamilial correlations of left ventricular mass differed. The mother-son (n=140, r=0.27, P<0.001) and mother-daughter (n=161, r=0.28, P<0.001) correlations were significant, whereas the father-son (n=101, r=0.04, P=0.69) and father-daughter (n=98, r=-0.09, P=0.38) correlations were not different from zero. Overall, the mother-offspring correlation coefficient was significantly higher than the father-offspring correlation (r=0.28 versus r=-0.04; P=0.005). Thus, maternal factors appear to have more impact on left ventricular mass of offspring than do paternal influences. Further studies are required to elucidate the genetic, epigenetic, and ecogenetic mechanisms underlying these divergent parent-offspring correlations.

Cross-sectional and longitudinal associations between body mass index and marriage-related factors

OBJECTIVE

To assess the relationship between marriage and obesity.

RESEARCH METHODS AND PROCEDURES

Cross-sectional and longitudinal associations were examined between participant body mass index (BMI), spouse BMI, and participant diet and exercise habits.

RESULTS

Spouse and participant BMI and BMI changes over 2 years were significantly associated. Participant BMI was associated with higher consumption of calorie-dense foods and lower frequency of physical activity. Participants' eating and exercise habits were only weakly related to spouse BMI. BMI did not predict the likelihood of marriage or divorce. However, marriage was associated with a significant 2-year weight gain and divorce with a significant 2-year weight loss.

DISCUSSION

The results suggest that spouse similarity in BMI is at least partly due to shared environment. The observed effects of marriage and divorce on weight may be due to the influence of marriage on inducements to eat (e.g., shared meals) or on motivation for weight control.

Effects of three candidate genes on prevalence and incidence of hypertension in a Caucasian population

BACKGROUND

The genes encoding angiotensin converting enzyme (ACE, I/D), alpha-adducin (ADD, Gly460Trp) and aldosterone synthase (AS, -344C/T) share the potential of influencing blood pressure (BP) via sodium homeostasis. However, most studies in humans focused on single-gene effects and disregarded epistasis, the suppression or potentiation of a gene by other non-allelic genes.

METHODS

We studied the singular and combined effects of the aforementioned candidate genes: (1) in relation to BP, plasma renin activity (PRA) and urinary aldosterone in 1461 subjects randomly selected from a Caucasian population; and (2) in relation to the incidence of hypertension in a subgroup of 678 initially normotensive subjects followed up for 9.1 years (median).

RESULTS

In cross-sectional analyses, AS/CC homozygosity was associated with slightly lower systolic BP (-1.32 mmHg; P = 0.08). AS/TT homozygotes showed both lower PRA and higher urinary aldosterone excretion (P < or = 0.05). In multiple-gene analyses, compared with the whole study population, ADD/Trp subjects had a higher relative risk of hypertension in the presence of the AS/T allele (1.29; P = 0.05), whereas in combination with AS/CC homozygosity ADD/Trp subjects had the smallest relative risk (0.48; P = 0.003). Hypertension developed in 229 subjects (36.6 cases per 1000 person-years). ACE/DD homozygosity, in comparison with the other ACE genotypes, was associated with increases in the incidence of hypertension, which amounted to 31% (P = 0.005) in single-gene analyses, to 59% (P = 0.004) in carriers of the ADD/Trp allele and to 122% (P = 0.0007) in AS/CC subjects. Among subjects who had both the ADD/Trp allele and the AS/CC genotype, ACE/DD homozygotes manifested a 252% (P = 0.001) higher incidence of hypertension.

CONCLUSIONS

Epistatic interactions between the ACE, ADD and AS genes contribute to the prevalence and incidence of hypertension in Caucasians. The clinical relevance of the risk-conferring haplotypes identified in our prospective study was underscored by their positive predictive values, which under the assumption of a 20% life-time risk of hypertension, ranged from 29.8-40.1%.

Differences in familial segregation of FEV1 between asthmatic and nonasthmatic families. Role of a maternal component

Studies have demonstrated familial aggregation of lung function. This study employed segregation analysis to investigate the mode of inheritance of FEV1 using regressive models for continuous traits. The study population comprised 309 families (1,163 individuals) enrolled in the Tucson Children's Respiratory Study who had both parents and at least one child with FEV1 data. Results showed significant genetic heterogeneity among the 87 families (328 individuals) with at least one member with asthma and the 222 families (835 individuals) with no asthmatic members. In families with no asthmatic members, all statistical models were rejected, indicating the absence of a major gene controlling lung function. However, a significant familial component indicated a strong polygenic/multifactorial mode of inheritance. In families with asthmatic member(s), results suggested polygenic/multifactorial inheritance with weak evidence for a Mendelian component expressed in a recessive fashion. However, while both father-offspring and mother-offspring correlations were statistically significant in families with no asthmatic members, only the mother-offspring correlation was significant in families with asthmatic members. The data suggest that lung function is inherited as a polygenic/multifactorial trait, but in asthmatic families a major element of intergenerational correlation is associated with a maternal influence, which may be genetically or environmentally mediated.

Family history as a predictor of blood pressure in a longitudinal study of Australian children

BACKGROUND

Sex both of parent and of child might influence associations between parental hypertension and blood pressure in offspring.

OBJECTIVE

To examine these associations.

DESIGN

A cohort of Australians was surveyed 3-yearly from age 9 to 18 years.

SETTING

A community-based sample.

PARTICIPANTS

When they were aged 18 years, 630 of 1565 participants who had been selected randomly at the age of 9 years were re-surveyed.

MAIN OUTCOME MEASURES

Systolic and diastolic blood pressures.

RESULTS

Paternal hypertension was reported by 18% of men and 15% of women and maternal hypertension by 15% of men and 14% of women. By the time they were aged 9 years, systolic blood pressure was significantly higher in sons [117.8 mmHg, 95% confidence interval (CI) 116A-119.2 versus 114.7 mmHg, CI 113.4-116.0] and daughters (118.2 mmHg, CI 116.9-119.5 versus 114.9 mmHg, CI 112.8-117.0) of hypertensive fathers than it was in sons and daughters of normotensive fathers. When they were aged 18 years, paternal hypertension predicted blood pressures in men and women independently of their weight at birth, fitness, alcohol consumption and weight for height for age. Systolic blood pressures increased more rapidly (by 0.6 mmHg/year) in men with hypertensive fathers.

CONCLUSIONS

Systolic blood pressure in young adults differs in relation to parental hypertension according to the sex of the affected parent and the sex of the offspring. This could reflect unmeasured environmental variables or the action of sex-related genetic or intrauterine factors.

Heritability of conventional and ambulatory blood pressures. A study in twins

Conventional and 24-hour ambulatory blood pressures were measured in 26 pairs of monozygotic twins and 27 pairs of dizygotic twins, all male, ages 18 to 38 years, to determine the heritability of blood pressure measured under various conditions. Conventional pressure was the average of three well-standardized measurements in the supine position, and ambulatory pressure was recorded during the subjects' normal activities by use of the SpaceLabs 90202 device. Heritability was assessed by classic methods and by model fitting and path analysis. In the latter approach, the percent genetic variance was 70% for mean 24-hour systolic pressure and 73% for diastolic pressure, which was similar to the results for the conventional pressures (64% and 73%, respectively). During the night, these estimates were 72% and 51% for systolic and diastolic pressures, respectively, and also the average pressures of the total awake daytime period were under partial genetic control (63% and 55%, respectively). The remaining variances could be attributed primarily to unique environmental influences. However, shared and nonshared environmental factors were predominant for the pressures during a fixed 6-hour afternoon period. We conclude that the heritability of blood pressure is relatively high in young adult healthy men, for standardized conventional pressure and the average 24-hour pressure. Genetic variance is somewhat higher for the asleep pressure than for the awake systolic pressure.

Insulin and hypertension: are they related?

It has been postulated that insulin resistance and the concomitant compensatory hyperinsulinemia contribute to the pathogenesis of hypertension, possibly by stimulating the sympathetic nervous system, promoting renal sodium reabsorption, modulating cation transport, and/or stimulating vascular smooth muscle hypertrophy. The purpose of this article is to present a comprehensive up-to-date review of the literature and critically examine the insulin resistance-hyperinsulinemia-hypertension hypothesis.

A prospective study of familial aggregation of blood pressure in young children

In a prospective study, we evaluated familial aggregation of blood pressure in a sample of 175 normotensive families with children 3 to 6 yr old. Systolic and diastolic blood pressure measurements of parents and children were correlated at 1, 2, and 3 yr intervals. Spearman rank-order correlation coefficients between parents and children were significant for mother-son pairs. In particular, mother-son blood pressure correlation coefficients were significant for systolic blood pressure across all 3 yr and for diastolic blood pressure during yr 2. Further analyses were performed adjusting for body mass index (BMI), age, physical activity, sodium intake, potassium intake, and parental smoking status, and alcohol use. The Spearman correlation coefficients for mother-son pairs remained significant for yr 1 and 3 after adjusting for these blood pressure correlates. These results are consistent with cross-sectional studies and suggest that both genetic and environmental contributions to blood pressure status are important in young children.

Familial aggregation of blood pressure in a paediatric population

Familial aggregation of blood pressure in childhood and the difference between males and females were studied in a random sample of a nursery and school-age population in Milan. Age, sex, height, weight, skinfold thicknesses and heart rate were obtained. Blood pressure was measured in accordance with the recommendations of the Task Force of Blood Pressure Control in Children. After adjusting for age, significant correlation coefficients were found between mother and son (r = 0.17 and r = 0.11), mother and daughter (r = 0.11 and r = 0.15), and father and son (r = 0.16 and r = 0.17) for systolic and diastolic pressure, respectively; the father-daughter correlations were not statistically different (r = 0.08 and r = 0.03). Multiple regression analysis underlined the difference between males and females; height was an important determinant in the males and body weight in the females. In conclusion, anthropometric measurements should be considered in evaluations of blood pressure status. Our results suggest important differences between males and females. The BP pattern of the parents also seems more important for sons, and there seems to be a lower correlation between fathers and daughters.

The nature/nurture controversy: spouse-likeness revisited

Within the past twelve months two distinguished scientific journals have once again raised the issue of nature versus nurture in health and sickness. The conclusion continues to be simply that both genetics and environment play a role. The issue still to be resolved is the relative contributions of nature and nurture. The model which most contributes to the answer is the very one least employed, namely spouse-likeness. This is a review of the approximately 100 most recent articles. It is evident that, within the limits of these observations, environment may play a more dominant role than generally considered.

Biochemical investigation of hypertension

Underlying causes of hypertension are found in less than 5% of cases but they are frequently surgically remediable. Elementary biochemical tests are usually sufficient to exclude most renal and endocrine causes of hypertension. However, young patients with very high blood pressures merit more detailed investigation in specialized centres. As coexistent hyperlipidaemia or glucose intolerance substantially worsen the prognosis for a given level of blood pressure, these two risk factors are worth assessing in all hypertensive patients. Their presence may also alter the choice of antihypertensive drug therapy. About 25% of the population have raised blood pressure at first screening and about 10% are in need of drug therapy, so this represents an appreciable load on biochemical laboratories. Most patients, however, need only a single biochemical profile on one occasion, and should be exclusively managed in general practice.

Aggregation of blood pressure in Anglo-American and Mexican-American families

We investigated the aggregation of blood pressure within 95 Anglo-American and 111 Mexican-American families. Degree of genetic relatedness was evaluated by calculating separate correlations for spouses and for each spouse with both same-sex and opposite-sex offspring. In addition, sibling correlations were evaluated. These analyses were performed separately for Anglo-American and Mexican-American families. Replicating earlier findings, correlations between blood pressures of Anglo spouses were nonsignificant. However, there were significant spousal correlations in the Mexican-American group. For Anglo-American families, there were significant associations between blood pressures of fathers and sons and between blood pressures of mothers and daughters. Correlations between blood pressures for opposite-sex parent-child pairs were nonsignificant. In the Mexican-American group, there were significant correlations between fathers' blood pressures and those of both male and female offspring. For mothers, blood pressures were weakly correlated with all other family members. These relationships remained after adjustment for age, body mass index, and measures of dietary habits and activity levels. In general, blood pressure aggregation was greater in Mexican-American families.

Familial correlations from genes and shared environment for urine, plasma, and intraerythrocytic sodium

Spouse-spouse, sib-sib, and parent-offspring correlations were calculated for urinary, plasma, and intracellular sodium levels on over 1,900 persons aged 3-86 years in 98 Utah kindreds. For 36 hours prior to their clinic visit, 31% of the sample was salt-loaded with salt tablets, while the rest followed their normal diet. For those on their normal diet, urine creatine-, age-, and sex-adjusted urinary sodium excretion from a timed 12-hour overnight sample showed similar and significant correlations between spouses (r = .29), sibs less than 20 years old (r = .38), and parent-offspring pairs for offspring less than 20 years old (r = .29). This contrasted with the lower correlations between sibs 20 years of age and older (r = .10) and parent-offspring pairs for offspring 20 years of age and older (r = .13), presumed to live in different households. Adult plasma sodium sib-sib (r = .13) and parent-offspring (r = .15) correlations were similar to the urinary sodium correlations, while the spouse-spouse (r = .48), the sib-sib (r = .64), and the parent-offspring (r = .63) correlations for those presumed to live in the same household nearly doubled. Intracellular sodium correlations for the adult sibs (r = .32) and offspring (r = .36) were over twice as large as for urinary or plasma sodium, although the spouse-spouse correlation (r = .37) remained large also.(ABSTRACT TRUNCATED AT 250 WORDS)