Familial (shared environmental and genetic) factors and the foetal origins of cardiovascular diseases and type 2 diabetes: a review of the literature

Birth weight and subclinical cardiovascular and renal damage in a population-based study (the STANISLAS cohort study)

OBJECTIVE

Although preterm-born and low-birth-weight individuals have an increased risk of cardiovascular diseases in adulthood, little is known regarding early cardiovascular and renal damage (CVRD) or hypertension in adulthood. Our study investigated the association of birth weight with early CVRD markers as well as the heritability of birth weight in an initially healthy family-based cohort.

METHODS

This study was based on 1028 individuals from the familial longitudinal STANISLAS cohort (399 parents/629 children) initiated in 1993-1995, with a fourth examination conducted in 2011-2016. Analyses performed at the fourth visit included pulse-wave velocity, central pressure, ambulatory blood pressure, hypertension status, diastolic dysfunction/distensibility, left ventricular mass indexed (LVMI), carotid intima-media thickness and kidney damage. The family structure of the cohort allowed birth weight heritability estimation.

RESULTS

Mean (±SD) birth weight was 3.3 ± 0.6 kg. Heritability was moderate (42-44%). At the fourth visit, individuals were 37 years old (32.0-57.0), 56% were women and 13% had antihypertensive treatment. Birth weight was strongly and negatively associated with hypertension [odds ratio (OR) 95% confidence interval (CI) 0.61 (0.45-0.84)]. A nonlinear association was found with LVMI, participants with a birth weight greater than 3 kg having a higher LVMI. A positive association ( β 95% CI 5.09 (1.8-8.38)] was also observed between birth weight and distensibility for adults with normal BMI. No associations were found with other CVRD.

CONCLUSION

In this middle-aged population, birth weight was strongly and negatively associated with hypertension, and positively associated with distensibility in adults with normal BMI and with LVMI for higher birth weights. No associations were found with other CVRD markers.

Early life programming of adult ischemic heart disease within and across generations: The role of the socioeconomic context

BACKGROUND

The developmental origins of ischemic heart disease (IHD) have been widely documented but little is known about their persistence across more than one generation. This study aimed to investigate whether the effects of early life disadvantages on adult IHD have changed between generations and are mediated by adult socioeconomic circumstances, and further explore the transgenerational effects of grandparental and parental exposures to disadvantaged circumstances on adult offspring's IHD.

METHODS

We used register-based data from the Uppsala Multigenerational Study, Sweden. The study populations were the parents born 1915-1929 and their offspring born 1932-1972 with available obstetric data. The offspring were further linked to grandparents who had their socioeconomic and demographic data recorded. The outcome was incident IHD assessed at ages 32-75 during a follow-up from January 1, 1964 till December 31, 2008. The exposures included birthweight standardized-for-gestational age, ponderal index, gestational length, and parental socioeconomic position (SEP). Education and income were analyzed as mediators. Potential transgenerational associations were explored by linking offspring IHD to parents' standardized birthweight and gestational length, grandparental SEP, and to grandmothers' age, parity, and marital status at parental birth. All associations were examined in Cox proportional hazard regression models.

RESULTS

Lower standardized birthweight and lower parental SEP were found to be associated with higher IHD rates in both generations, with no evidence of effect modification by generation. Education and income did not mediate the association between standardized birthweight and IHD. Disadvantaged grandparental SEP, younger and older childbearing ages of grandmothers, and paternal preterm birth affected offspring's IHD independent of parental education, income, or IHD history.

CONCLUSIONS

The findings point to similar magnitudes of IHD inequalities by early life disadvantages across two historical periods and the existence of transgenerational effects on IHD. Epigenetic dysregulation involving the germline is a plausible candidate mechanism underlying the transgenerational associations that warrant further research.

Birthweight in offspring and cardiovascular mortality in their parents, aunts and uncles: a family-based cohort study of 1.35 million births

Background

A link between suboptimal fetal growth and higher risk of cardiovascular disease (CVD) is well documented. It has been difficult to assess the contribution of environmental versus genetic factors to the association, as these factors are closely connected in nuclear families. We investigated the association between offspring birthweight and CVD mortality in parents, aunts and uncles, and examined whether these associations are explained by CVD risk factors.

Methods

We linked Norwegian data from the Medical Birth Registry, the Cause of Death Registry and cardiovascular surveys. A total of 1 353 956 births (1967–2012) were linked to parents and one maternal and one paternal aunt/uncle. Offspring birthweight and CVD mortality association among all relationships was assessed by hazard ratios (HR) from Cox regressions. The influence of CVD risk factors on the associations was examined in a subgroup.

Results

Offspring birthweight was inversely associated with CVD mortality among parents and aunts/uncles. HR of CVD mortality for one standard deviation (SD) increase in offspring birthweight was 0.72 (0.69–0.75) in mothers and 0.89 (0.86–0.92) in fathers. In aunts/uncles, the HRs were between 0.90 (0.86–0.95) and 0.93 (0.91–0.95). Adjustment for CVD risk factors in a subgroup attenuated all the associations.

Conclusions

Birthweight was associated with increased risk of CVD in parents and in aunts/uncles. These associations were largely explained by CVD risk factors. Our findings suggest that associations between offspring birthweight and CVD in adult relatives involve both behavioural variables (especially smoking) and shared genetics relating to established CVD risk factors.

Lasting Effects of Intrauterine Exposure to Preeclampsia on Offspring and the Underlying Mechanism

Preeclampsia is a common pregnancy complication which can have adverse impact on both mother and baby. In addition to the short term effects, a large body of epidemiological evidence has found preeclampsia can exert long-lasting effects on mother and offspring. Studies suggest that offspring exposed to preeclampsia are at a higher risk of developing cardiovascular, metabolic, and neurological diseases, as well as other diseases. However, studies investigating the underlying mechanism are limited, the exact mechanism still remains unclear. In this study, we will review the epidemiological evidence and studies exploring the mechanism underlying long-term effects of preeclampsia on offspring. Further studies should be targeted at this field so as to implement effective clinical management to prevent the exposed offspring from potential diseases.

Glycan-based biomarkers for diagnosis of cancers and other diseases: Past, present, and future

Glycans are essential biomolecules in regulating human physiology and pathology ranging from signal transduction to microbial infections. Developing complex human diseases, such as cancer, diabetes, and cardiovascular diseases, are a combination of genetic and environmental factors. Genetics dominates embryonic development and the passing of genes to the next generation whereas the information in glycans reflects the impact of internal and external environmental factors, such as diseases, lifestyle, and social factors, on a person's health and disease. The reason behind this is that glycans are not directly encoded in a genetic template. Instead, they are assembled dynamically by hundreds of enzymes organized in more than 10 complex biosynthetic pathways. Any environmental changes affecting enzymatic activities or the availability of high-energy monosaccharide donors in a specific location will disturb the final structure of glycans. The glycan structure-dependent biological activities subsequently enable or disable gene expressions, which partially explain that it is difficult to pinpoint specific genetic defects to aging-associated diseases. Glycan-based biomarkers are currently used for diagnosis of diabetes, cancers, and other complex diseases. We will recapitulate the discovery of glucose, glycated proteins, glycan-, and glycoprotein-based biomarkers followed by summarizing clinically used glycan/glycoprotein-based biomarkers. The potential serum/plasma-derived N- and O-linked glycans as biomarkers will also be discussed.

Sex-Specific Associations Between Complement Component 3 and Component 4 Levels and Metabolic Syndrome in an Adult Population

BACKGROUND

Metabolic syndrome (MetS) is a cluster of cardiovascular and metabolic risk factors in the same individual. Inflammation has been reported to be directly involved in the development of metabolic disease. Complement component 3 (C3) and complement component 4 (C4) have been identified as important inflammatory markers relevant to metabolic disease. However, few studies have analyzed the association between C3 and/or C4 and MetS. In this study, our aim is to evaluate sex-specific association between C3 and C4 levels and risk of MetS in an adult population.

METHODS

A cohort of 4635 adults was followed from 2010 to 2016. Serum C3 and C4 levels were measured using an immunonephelometric technique. MetS was defined by the American Heart Association scientific statements of 2009. Cox proportional hazard regression models were used to assess sex-specific association between C3 and C4 levels and the incidence of MetS.

RESULTS

During the ∼6 years of follow-up, 1445 new cases of MetS were identified. After being adjusted to confounding factors, the hazard ratios (95% confidence interval) of MetS for gradually increasing quintiles of C3 were 1.00, 1.23 (0.98-1.54), 1.50 (1.21-1.87), 1.64 (1.32-2.04), and 1.75 (1.41-2.18) (P for trend <0.0001) in men and 1.00, 0.96 (0.60-1.53), 1.61 (1.06-2.44), 2.01 (1.34-3.03), and 2.43 (1.63-3.63) (P for trend <0.0001) in women, respectively. Similar results were also obtained for gradually increasing quintiles of C4 in women, but not in men.

CONCLUSIONS

The levels of C3 were significantly associated with the incidence of MetS in both men and women. The levels of C4 contributed to risk of MetS only in women.

Offspring birth weight and cardiovascular mortality among parents: the role of cardiovascular risk factors

An inverse association between offspring birth weight (BW) and higher risk of parental cardiovascular disease (CVD) mortality and morbidity has been reported. Shared environmental, genetic and intrauterine factors may be responsible for explaining these associations. We studied the role of parental CVD risk factors in the association between offspring BW and CVD mortality among mothers and fathers. All births registered in Medical Birth Registry Norway (1967–2012) were linked to three health surveys, National Educational Registry and Cause of Death Registry. Number of births with information of parental CVD risk factors available for the analyses was 1,006,557 (520,670 for mothers and 485,887 for fathers). Cox proportional hazards regression models were used, following CVD deaths in parents from 1974 to 2012. An inverse association between offspring BW and CVD mortality was observed among both parents: hazard ratio 1.60 (1.44–1.75) for mothers and 1.16 (1.10–1.23) for fathers. Among mothers, adjustment for smoking, triglycerides and diabetes reduced the risk to 1.36 (1.25–1.52), 1.57 (1.43–1.73) and 1.58 (1.43–1.79), respectively. Adjustment for diastolic blood pressure (DBP) and systolic blood pressure (SBP) both reduced the risk to 1.53 (1.37–1.66). Among fathers, adjustments for smoking, DBP, SBP reduced the risk to 1.08 (1.02–1.15), 1.13 (1.06–1.19) and 1.14 (1.08–1.22), respectively. Triglycerides and diabetes both reduced the risk to 1.15 (1.09–1.12). Our results indicate that shared environmental factors might be important in the association. A stronger association in mothers suggest that intrauterine factors also are at play.

Birth weight and subsequent body mass index in children: an international cross-sectional study

BACKGROUND

The reported association between birth weight and subsequent body mass index (BMI) is conflicting.

OBJECTIVES

To examine the relationship between birth weight and BMI in children aged 6-7 years.

METHODS

Secondary analysis of data from a multi-centre, multi-country, cross-sectional study (International Study of Asthma and Allergies in Childhood (ISAAC) Phase Three). Parents/guardians of children aged 6-7 years completed questionnaires about their children's birth weight, current height and weight and whether their mother smoked in the first year of the child's life. A general linear mixed model was used to determine the association between BMI and birth weight.

RESULTS

A total of 72 111 children (17 countries) were included in the analysis. There was a positive association of birth weight with BMI (for each kg increase in birth weight the BMI at 6-7 increased by 0.47 (SE 0.02) kg/m² ; p < 0.0001) with a clear gradient by birth weight category. There was no statistically significant interaction between birth weight and Gross National Income (GNI).

CONCLUSIONS

There is a positive linear relationship between birth weight and BMI in 6-7 year old children, which is present in both high and low income countries.

Serum levels of immunoglobulins in an adult population and their relationship with type 2 diabetes

OBJECTIVE

Some studies have found patients with diabetes had an impaired humoral immune response. Immunoglobulins provide key information on the humoral immune status. But few population-based studies comprehensively estimated the serum immunoglobulins concentration in type 2 diabetes (T2D). So we design a cross-sectional study to investigate the relationships between immunoglobulin levels and prevalence of T2D in a large-scale adult population.

METHODS

A cross-sectional assessment was performed in 10,691 participants living in Tianjin, China. Type 2 diabetes was defined in accordance with the criteria of the world health organization, and serum levels of immunoglobulins were determined by the immunonephelometric technique. Adjusted logistic models were used to assess relationships between the quintiles of immunoglobulins concentration and the prevalence of T2D.

RESULTS

In this study, the prevalence of T2D was 11.7%, and the means (standard deviation) of immunoglobulins (IgG, IgE, IgM, IgA) were 1192.3 (241.1)mg/dL, 92.3 (234.6)IU/mL, 104.8 (55.8)mg/dL, 234.1 (96.2)mg/dL, respectively. The adjusted odds ratio (95% confidence interval) of T2D for the highest immunoglobulins (IgG, IgE, IgM, IgA) quintile, when compared to the lowest quintile were 0.64 (0.52, 0.78), 1.00 (0.81, 1.22), 0.77 (0.62, 0.95) and 1.57 (1.29, 1.92), respectively.

CONCLUSIONS

Decreased IgG and IgM, and increased IgA levels were independently related to the prevalence of T2D among the adult population. Our findings indicate that the immunoglobulins might useful predictive factors for T2D in the general adult population. Further studies are needed to explore the causality and exact mechanisms of immunoglobulins in T2D.

Intellectual Functioning in Children with Congenital Heart Defects Treated with Surgery or by Catheter Interventions

BACKGROUND

Studies suggest that children with congenital heart defects (CHD) are at risk for adverse intellectual functioning. However, factors related to lower intellectual functioning in this group are largely unknown. This study describes intellectual functioning in children with CHD in relation to severity of the heart defect, the child's age, and the socioeconomic status of the family (SES).

METHODS

Two hundred twenty-eight children treated with surgery or by catheter technique were tested using the Wechsler intelligence scales to determine full scale IQ (FSIQ). FSIQ was then analyzed in relation to age (3-, 5-, 9-, and 15-year olds), severity of the diagnosis (mild, moderate, and severe), and SES (low, medium, and high). The median age was 70 months (5.8 years) with a range of 162 months [30 months (2.5 years) to 192 months (16.0 years)].

RESULTS

The total mean score on FSIQ was 100.8 (SD = 14.5). Children with severe CHD had significantly lower FSIQ than children with mild and moderate CHD, and 9- and 15-year olds had significantly lower FSIQ compared to the 3-year olds. Children from families with low SES had significantly lower FSIQ than children from medium SES and high SES families. No interaction between severity of diagnosis, age, and SES was found for FSIQ.

CONCLUSION

Eighty-three percent of the children with CHD performed at or above average with respect to FSIQ. SES and severity of diagnosis had significant main effects on FSIQ. These factors should be considered when planning interventions and follow-up programs for children with CHD.

Grandparental morbidity and mortality patterns are associated with infant birth weight in the Lifeways cross-generation cohort study 2001-2010

The association of infants' birth weight with maternal cardiovascular morbidity (CVD) and mortality substantiates the foetal origins hypothesis. Few studies to date have investigated grandparent-infant risk association. We prospectively examined this relationship in the Lifeways three-generation familial cohort, contrasting lineage and gender differences to understand mechanisms of intergenerational risk transmission. In 2001, a cohort of 1082 families was established at antenatal stage. A total of 539 families (n = 539 infants) had both a participating grandparent (n = 1054) and information on infants' gestational age. At baseline, grandparents provided their diagnosed CVD status and 79% also underwent a cardiovascular risk factors assessment. In 2005, general practitioners provided an update for 61% grandparents. In 2010, a search of civil register confirmed 77 grandparental deaths in 539 families. Grandchildren's birth weight and grandparental cardiovascular risk factors associations were examined with linear regressions. Grandparental CVD associations were analysed using ANCOVA. Cox proportional hazard ratios (HR) were calculated for all-cause mortality associations. Models were adjusted for infants', mothers' and grandparents' demographic, anthropometric and socio-behavioural characteristics, as appropriate. The paternal grandfathers' (PGF) systolic blood pressure (mmHg) [β (95% CI) = 6.6 (0.8 - 12.5); P = 0.03] and paternal grandmothers' serum triglycerides (mmol/l) [β (95% CI) = 78.8 (7.0 - 150.7); P = 0.03] were linearly predictive of infants' birth weight, which was not observed for maternal grandparents. Mean birth weight for infants of maternal grandmothers with diabetes {-272.7 [(-499.7) - (-45.6)] g; P = 0.02} or stroke {-292.1 [(-544.5) - (-39.6)] g; P = 0.02} was lower than those without diabetes or stroke, a pattern not observed for paternal grandparents. Whereas PGFs' mortality was significantly associated with infants' high birth weight (≥4000 g) [HR (95% CI) = 4.9 (1.2 - 19.9); P = 0.03], maternal grandparents' mortality showed a converse pattern with infants' low birth weight (<2500 g) [HR (95% CI) = 1.7 (0.4 - 8.2); P = 0.7], although not statistically significant. These findings suggest that intergenerational transmission of risk differs in maternal and paternal lines.

Progression from optimal blood glucose and pre-diabetes to type 2 diabetes in a high risk population with or without hypertension in Isfahan, Iran

AIM

To estimate the progression rates from normal glucose tolerance (NGT), isolated impaired glucose tolerance (IGT), isolated impaired fasting glucose (IFG) and combined IFG/IGT to type 2 diabetes (T2D) in a high risk population with and without hypertension (HTN) in Isfahan, Iran.

METHODS

During a mean (SD) follow-up period of 6.8 (1.7) years, 1489 non-diabetic first-degree relatives of patients with T2D with or without HTN were followed for the occurrence of T2D. At baseline and through follow-ups, participants underwent a standard 75g 2-h oral glucose tolerance test. Blood pressure was measured by standardised protocols and HTN was defined according to the criteria of the JNC7.

RESULTS

The progression rate (95% confidence interval) from NGT, isolated IFG, isolated IGT, and combined IFG/IGT to T2D was 10.0 (4.3, 19.6), 21.7 (9.5, 42.3), 28.2 (12.3, 54.7) and 64.7 (41.0, 96.4) per 1000 person-years in participants with HTN and 3.1 (1.5, 4.7), 16.3 (10.3, 24.2), 25.9 (17.0, 37.7) and 57.9 (46.1, 71.7) per 1000 person-years in participants without HTN based on 10,134 person-years of follow-up. Compared with individuals with NGT and without HTN, individuals with NGT and HTN, isolated IFG, isolated IGT, and combined IFG/IGT with or without HTN at baseline were more likely to progress to T2D. Compared with participants without HTN, individuals with concomitant HTN were not significantly more likely to progress to T2D.

CONCLUSIONS

Compared with individuals without HTN, the presence of NGT, isolated IFG, isolated IGT, and combined IFG/IGT with concomitant HTN was not associated with higher likelihood of progression to T2D in high-risk individuals in Iran.

Weight at birth and subsequent fecundability: a prospective cohort study

Objective

To examine the association between a woman's birth weight and her subsequent fecundability.

Method

In this prospective cohort study, we included 2,773 Danish pregnancy planners enrolled in the internet-based cohort study “Snart-Gravid”, conducted during 2007–2012. Participants were 18–40 years old at study entry, attempting to conceive, and were not receiving fertility treatment. Data on weight at birth were obtained from the Danish Medical Birth Registry and categorized as <2,500 grams, 2,500–2,999 grams, 3,000–3,999 grams, and ≥4,000 grams. In additional analyses, birth weight was categorized according to z-scores for each gestational week at birth. Time-to-pregnancy measured in cycles was used to compute fecundability ratios (FR) and 95% confidence intervals (CI), using a proportional probabilities regression model.

Results

Relative to women with a birth weight of 3,000–3,999 grams, FRs adjusted for gestational age, year of birth, and maternal socio-demographic and medical factors were 0.99 (95% CI: 0.73;1.34), 0.99 (95% CI: 0.87;1.12), and 1.08 (95% CI: 0.94;1.24) for birth weight <2,500 grams, 2,500–2,999 grams, and ≥4,000 grams, respectively. Estimates remained unchanged after further adjustment for markers of the participant's mother's fecundability. We obtained similar results when we restricted to women who were born at term, and to women who had attempted to conceive for a maximum of 6 cycles before study entry. Results remained similar when we estimated FRs according to z-scores of birth weight.

Conclusion

Our results indicate that birth weight appears not to be an important determinant of fecundability.

Birth weight, physical morbidity, and mortality: a population-based sibling-comparison study

Associations between low birth weight (≤2,500 g) and increased risk of mortality and morbidity provided the foundation for the "developmental origins of health and disease" hypothesis. Previous between-family studies could not control for unmeasured confounders. Therefore, we compared differentially exposed siblings to estimate the extent to which the associations were due to uncontrolled factors. Our population cohort included 3,291,773 persons born in Sweden from 1973 to 2008. Analyses controlled for gestational age, among other covariates, and considered birth weight as both an ordinal and a continuous variable. Outcomes included mortality after 1 year, cardiac-related death, hypertension, ischemic heart disease, pulmonary circulation problems, stroke, and type 2 diabetes mellitus. We fitted fixed-effects models to compare siblings and conducted sensitivity analyses to test alternative explanations. Across the population, the lower the birth weight, the greater the risk of mortality (e.g., cardiac-related death (low birth weight hazard ratio = 2.69, 95% confidence interval: 2.05, 3.53)) and morbidity (e.g., type 2 diabetes mellitus (low birth weight hazard ratio = 1.79, 95% confidence interval: 1.50, 2.14)) outcomes in comparison with normal birth weight. All associations were independent of shared familial confounders and measured covariates. Results emphasize the importance of birth weight as a risk factor for subsequent mortality and morbidity.

Effects of early-life environment and epigenetics on cardiovascular disease risk in children: highlighting the role of twin studies

Cardiovascular disease (CVD) is the leading cause of death worldwide and originates in early life. The exact mechanisms of this early-life origin are unclear, but a likely mediator at the molecular level is epigenetic dysregulation of gene expression. Epigenetic factors have thus been posited as the likely drivers of early-life programming of adult-onset diseases. This review summarizes recent advances in epidemiology and epigenetic research of CVD risk in children, with a particular focus on twin studies. Classic twin studies enable partitioning of phenotypic variance within a population into additive genetic, shared, and nonshared environmental variances, and are invaluable in research in this area. Longitudinal cohort twin studies, in particular, may provide important insights into the role of epigenetics in the pathogenesis of CVD. We describe candidate gene and epigenome-wide association studies (EWASs) and transgenerational epigenetic inheritance of CVD, and discuss the potential for evidence-based interventions. Identifying epigenetic changes associated with CVD-risk biomarkers in children will provide new opportunities to unravel the underlying biological mechanism of the origins of CVD and enable identification of those at risk for early-life interventions to alter the risk trajectory and potentially reduce CVD incidence later in life.

Neonatal DNA methylation profile in human twins is specified by a complex interplay between intrauterine environmental and genetic factors, subject to tissue-specific influence

Comparison between groups of monozygotic (MZ) and dizygotic (DZ) twins enables an estimation of the relative contribution of genetic and shared and nonshared environmental factors to phenotypic variability. Using DNA methylation profiling of ∼20,000 CpG sites as a phenotype, we have examined discordance levels in three neonatal tissues from 22 MZ and 12 DZ twin pairs. MZ twins exhibit a wide range of within-pair differences at birth, but show discordance levels generally lower than DZ pairs. Within-pair methylation discordance was lowest in CpG islands in all twins and increased as a function of distance from islands. Variance component decomposition analysis of DNA methylation in MZ and DZ pairs revealed a low mean heritability across all tissues, although a wide range of heritabilities was detected for specific genomic CpG sites. The largest component of variation was attributed to the combined effects of nonshared intrauterine environment and stochastic factors. Regression analysis of methylation on birth weight revealed a general association between methylation of genes involved in metabolism and biosynthesis, providing further support for epigenetic change in the previously described link between low birth weight and increasing risk for cardiovascular, metabolic, and other complex diseases. Finally, comparison of our data with that of several older twins revealed little evidence for genome-wide epigenetic drift with increasing age. This is the first study to analyze DNA methylation on a genome scale in twins at birth, further highlighting the importance of the intrauterine environment on shaping the neonatal epigenome.

Offspring birth weight and cardiovascular risk in parents: a population-based HUNT 2 study

Low birth weight is associated with increased risk of cardiovascular disease and type 2 diabetes in later life. The fetal insulin hypothesis suggests that shared genetic factors partly explain this association. If fetal genes predispose to both low birth weight and cardiovascular disease in adulthood, fathers of offspring with low birth weight should display an unfavorable profile of cardiovascular risk factors. To study this, the authors linked data on more than 14,000 parents, collected from the second Health Study of Nord Trøndelag County, Norway (HUNT 2, 1995-1997), to offspring data from the Norwegian Medical Birth Registry (1967-2005). Linear regression was used to study associations of offspring birth weight for gestational age with the parents' body mass index, waist circumference, blood pressure, glucose, and serum lipids. All analyses were adjusted for shared environment by means of the socioeconomic measures, lifestyle, and cardiovascular risk factors of the partner. The authors found that low offspring birth weight for gestational age was associated with increased paternal blood pressure, body mass index, waist circumference, and unfavorable levels of glucose and lipids. For mothers, associations similar to those for fathers were found for blood pressure, whereas associations in the opposite direction were found for glucose, lipids, and body mass index. The paternal findings strengthen the genetic hypothesis.

Birthweight and mortality in adulthood: a systematic review and meta-analysis

BACKGROUND

Small birth size may be associated with increased risk of cardiovascular diseases (CVD), whereas large birth size may predict increased risk of obesity and some cancers. The net effect of birth size on long-term mortality has only been assessed in individual studies, with conflicting results.

METHODS

The Meta-analyses of Observational Studies in Epidemiology (MOOSE) guidelines for conducting and reporting meta-analysis of observational studies were followed. We retrieved 22 studies that assessed the association between birthweight and adult mortality from all causes, CVD or cancer. The studies were systematically reviewed and those reporting hazard ratios (HRs) and 95% confidence intervals (95% CIs) per kilogram (kg) increase in birthweight were included in generic inverse variance meta-analyses.

RESULTS

For all-cause mortality, 36,834 deaths were included and the results showed a 6% lower risk (adjusted HR = 0.94, 95% CI: 0.92-0.97) per kg higher birthweight for men and women combined. For cardiovascular mortality, the corresponding inverse association was stronger (HR = 0.88, 95% CI: 0.85-0.91). For cancer mortality, HR per kg higher birthweight was 1.13 (95% CI: 1.07-1.19) for men and 1.04 (95% CI: 0.98-1.10) for women (P(interaction) = 0.03). Residual confounding could not be eliminated, but is unlikely to account for the main findings.

CONCLUSION

These results show an inverse but moderate association of birthweight with adult mortality from all-causes and a stronger inverse association with cardiovascular mortality. For men, higher birthweight was strongly associated with increased risk of cancer deaths. The findings suggest that birthweight can be a useful indicator of processes that influence long-term health.

The hypertension-diabetes continuum

Hypertension and type 2 diabetes are both common chronic conditions that affect a major proportion of the general population. They tend to occur in the same individual, suggesting common predisposing factors, which can be genetic or environmental. Although the genes causing hypertension or diabetes await elucidation, the environmental causes of these diseases are well known. Obesity and physical activity are the 2 leading factors that predispose to both diseases. Individuals with abdominal obesity are likely to develop lipid abnormalities and elevation of blood pressure and glucose. In time, hypertension and diabetes ensue. Because of the shared etiology, there is substantial overlap between hypertension and diabetes. In the Hong Kong Cardiovascular Risk Factor Prevalence Study, 40% of the subjects in the community had either raised blood pressure or raised blood glucose. Only 42% of people with diabetes had normal blood pressure and only 56% of people with hypertension had normal glucose tolerance. The presence of hypertension or diabetes should alert the clinician to the possibility of the other condition. Obesity, lipid abnormalities, raised blood pressure, and glucose are all components of the metabolic syndrome. The syndrome therefore implies a pathologic process, which is potentially reversible in the early stages. Previous efforts targeting smoking, hypertension, and hypercholesterolemia have started to bear fruit. However, obesity is on the increase in developed and developing countries. It is now time to focus on obesity and the metabolic syndrome, which require more a public health than a pharmacologic approach.

Associations of birthweight and gestational age with reproductive and metabolic phenotypes in women with polycystic ovarian syndrome and their first-degree relatives

CONTEXT

Low birthweight has been associated with metabolic and reproductive abnormalities in adults.

OBJECTIVE

The aim of the study was to examine the relationship between birthweight and gestational age and its association with reproductive and metabolic phenotypes in women with PCOS and their first-degree relatives.

DESIGN AND SETTING

We conducted a family-based study of PCOS at an academic health center.

PATIENTS OR OTHER PARTICIPANTS

A total of 1038 individuals (845 females and 193 males) from the cohort and 168 controls participated in the study.

MAIN OUTCOME MEASURES

The association between birthweight and familial phenotype was measured.

RESULTS

Self-reported and actual birthweight were highly correlated [Spearman correlation coefficient (r) = 0.81; 95% CI, 0.66, 0.89; P = 0.001) and concordant (concordance correlation coefficient = 0.86; 95% lower limit = 0.78). We noted that birthweight for both genders in PCOS families and controls fell within the 10th and 90th percentiles for gestational age based on U.S. population norms. The 50th percentiles for a gestational age of 40 wk were very similar (3409 g in PCOS, 3455 g for controls, and 3495 g for the United States). There were no significant associations between phenotype and birthweight in PCOS probands. Furthermore, there were not any significant relationships between phenotype and birthweight in female or male family members of the PCOS probands.

CONCLUSIONS

Birthweight in PCOS families mirrors control and U.S. population data, even corrected for gestational age, and has no substantive association with reproductive and metabolic abnormalities in women with PCOS, their female relatives, or their male relatives.

Type 2 diabetes in Belgians of Turkish and Moroccan origin

Objectives

To compare the prevalence of type 2 diabetes in adults aged 35 to 74 years of the Turkish and Moroccan communities in Belgium with the prevalence in native Belgians. To examine the determinants and specific mechanisms responsible for differences in diabetes between these communities.

Method

Both objectives were examined using the Health Interview Surveys of 1997, 2001 and 2004. Stepwise logistic regression analyses were performed with diabetes as the outcome variable. The variables 'age', 'sex', 'ethnic origin', 'body mass index', 'lack of physical activity', 'educational attainment' and 'income' were introduced in the model in consecutive steps.

Results

In 35- to 74-year-olds, the prevalence of type 2 diabetes is higher in Belgians of Tur-kish and Moroccan origin than in native Belgians. In native Belgian men, the prevalence amounts to 5.0%. In 35- to 74-year-old men of Turkish and Moroccan origin, the diabetes prevalence is 5.8% and 6.5% respectively. 4.3%, 18.7% and 11.9% of the women of Belgian, Turkish and Moroccan origin respectively suffer from diabetes. In men, differences in the prevalence of diabetes are strongly reduced after controlling for lack of physical activity and educational attainment. In women, differences remain high, although they become smaller after accounting for BMI and educational attainment.

Conclusions

In men, the differences in diabetes prevalence are explained by lifestyle factors and educational attainment. In women, the community differences in diabetes prevalence persist, although lifestyle factors and educational attainment play an important part in understanding these differences.

Emerging concepts in the pathophysiology of type 2 diabetes mellitus

Type 2 diabetes mellitus is a multifactorial metabolic disorder. It is characterized by chronic hyperglycemia, insulin resistance, and a relative insulin secretion defect. The prevalence of type 2 diabetes mellitus has risen worldwide in large part because of an increase in obesity and sedentary lifestyles. The underlying pathophysiology and complications of type 2 diabetes mellitus are still being elucidated. Recent advances in diabetes research have helped us to gain a better understanding about insulin resistance and insulin secretion defects. The evolving understanding about the influence of the incretin effect, insulin signal transduction, adipose tissue, intra-islet cell communication, and inflammation is changing the way in which we view type 2 diabetes mellitus. This new understanding will eventually provide us with new treatment approaches to help patients who have type 2 diabetes mellitus. This article gives a review of the current and emerging concepts of the pathophysiology of type 2 diabetes mellitus.