A saturated map of common genetic variants associated with human height

Common single-nucleotide polymorphisms (SNPs) are predicted to collectively explain 40-50% of phenotypic variation in human height, but identifying the specific variants and associated regions requires huge sample sizes1. Here, using data from a genome-wide association study of 5.4 million individuals of diverse ancestries, we show that 12,111 independent SNPs that are significantly associated with height account for nearly all of the common SNP-based heritability. These SNPs are clustered within 7,209 non-overlapping genomic segments with a mean size of around 90 kb, covering about 21% of the genome. The density of independent associations varies across the genome and the regions of increased density are enriched for biologically relevant genes. In out-of-sample estimation and prediction, the 12,111 SNPs (or all SNPs in the HapMap 3 panel2) account for 40% (45%) of phenotypic variance in populations of European ancestry but only around 10-20% (14-24%) in populations of other ancestries. Effect sizes, associated regions and gene prioritization are similar across ancestries, indicating that reduced prediction accuracy is likely to be explained by linkage disequilibrium and differences in allele frequency within associated regions. Finally, we show that the relevant biological pathways are detectable with smaller sample sizes than are needed to implicate causal genes and variants. Overall, this study provides a comprehensive map of specific genomic regions that contain the vast majority of common height-associated variants. Although this map is saturated for populations of European ancestry, further research is needed to achieve equivalent saturation in other ancestries.

Stunting, IQ, and final school attainment in the Cebu Longitudinal Health and Nutrition Survey birth cohort

School attainment is an important aspect of human capital, and a key determinant of long-term health and well-being. Early life deprivation and poor nutritional status are well known predictors of school entry and progression. We examine the persistence of early life influences and subsequent socioeconomic disadvantage (SED) across the multiple school continuation decisions that lead to final school attainment. Using data from a Philippine birth cohort followed for 35 years, we model 6 continuation decisions: Did not complete elementary school, elementary graduate only (completed grade 6), some secondary schooling, high school graduate, some postsecondary schooling, and college graduate, as well as total years of schooling. We estimate the association of school attainment with early life length for age Z-score (LAZ at 2 years of age) and cognitive development (IQ) as well as underlying indicators of SED and other family influences through early adulthood. The analysis sample includes >1900 participants in the Cebu Longitudinal Health and Nutrition Survey. Females completed, on average, one year more schooling than males, and twice as many females as males were college graduates (29.1 vs 15.0 %). LAZ and one standard deviation of IQ were each independently associated with 0.4 more years of attained schooling. A path model demonstrated strong direct associations of SED with years of schooling as well as indirect associations through LAZ and IQ. Sequential logits used to estimate continuing education decisions show persistent associations of early life LAZ and IQ and schooling even after accounting for changing SED of households over the schooling life course. Filipino parents had high but often unmet educational aspirations for their children because of the child's loss of interest in school and perceived financial barriers. Results further emphasize the importance of early life SED as a key risk factor for suboptimal school attainment.

Genetic Studies of Leptin Concentrations Implicate Leptin in the Regulation of Early Adiposity

Leptin influences food intake by informing the brain about the status of body fat stores. Rare LEP mutations associated with congenital leptin deficiency cause severe early-onset obesity that can be mitigated by administering leptin. However, the role of genetic regulation of leptin in polygenic obesity remains poorly understood. We performed an exome-based analysis in up to 57,232 individuals of diverse ancestries to identify genetic variants that influence adiposity-adjusted leptin concentrations. We identify five novel variants, including four missense variants, in LEP, ZNF800, KLHL31, and ACTL9, and one intergenic variant near KLF14. The missense variant Val94Met (rs17151919) in LEP was common in individuals of African ancestry only, and its association with lower leptin concentrations was specific to this ancestry (P = 2 × 10^-16, n = 3,901). Using in vitro analyses, we show that the Met94 allele decreases leptin secretion. We also show that the Met94 allele is associated with higher BMI in young African-ancestry children but not in adults, suggesting that leptin regulates early adiposity.

C-reactive protein response to influenza vaccination predicts cardiovascular disease risk in the Philippines

Inflammation is associated with increased risk for chronic degenerative diseases, as well as age-related functional declines across many systems and tissues. Current understandings of inflammation, aging, and human health are based on studies conducted almost exclusively in high-income nations that rely primarily on baseline measures of chronic inflammation. This analysis investigates the inflammatory response to vaccination as a predictor of cardiovascular disease (CVD) among older women in the Philippines, a lower-middle income nation with rising rates of overweight/obesity and relatively high burdens of infectious disease. Concentrations of C-reactive protein (CRP) were measured at baseline and 72 h following influenza vaccination in 530 women (mean age = 55.2 years). Ankle-brachial index (ABI) - an indicator of peripheral arterial disease and broader CVD risk - was measured approximately three years later. The magnitude of CRP response to vaccination was positively associated with ABI, indicating that a larger inflammatory response predicts lower CVD risk. Baseline CRP was negatively associated with CRP response to vaccination, and was not associated with ABI independently of CRP response. These results suggest that research across ecological settings, and with more dynamic measures of inflammatory response and regulation, may yield important insights into the associations among inflammation, aging, and disease.

Associations of autozygosity with a broad range of human phenotypes

In many species, the offspring of related parents suffer reduced reproductive success, a phenomenon known as inbreeding depression. In humans, the importance of this effect has remained unclear, partly because reproduction between close relatives is both rare and frequently associated with confounding social factors. Here, using genomic inbreeding coefficients (FROH) for >1.4 million individuals, we show that FROH is significantly associated (p < 0.0005) with apparently deleterious changes in 32 out of 100 traits analysed. These changes are associated with runs of homozygosity (ROH), but not with common variant homozygosity, suggesting that genetic variants associated with inbreeding depression are predominantly rare. The effect on fertility is striking: FROH equivalent to the offspring of first cousins is associated with a 55% decrease [95% CI 44-66%] in the odds of having children. Finally, the effects of FROH are confirmed within full-sibling pairs, where the variation in FROH is independent of all environmental confounding.

Exome-Derived Adiponectin-Associated Variants Implicate Obesity and Lipid Biology

Circulating levels of adiponectin, an adipocyte-secreted protein associated with cardiovascular and metabolic risk, are highly heritable. To gain insights into the biology that regulates adiponectin levels, we performed an exome array meta-analysis of 265,780 genetic variants in 67,739 individuals of European, Hispanic, African American, and East Asian ancestry. We identified 20 loci associated with adiponectin, including 11 that had been reported previously (p < 2 × 10^-7). Comparison of exome array variants to regional linkage disequilibrium (LD) patterns and prior genome-wide association study (GWAS) results detected candidate variants (r² > .60) spanning as much as 900 kb. To identify potential genes and mechanisms through which the previously unreported association signals act to affect adiponectin levels, we assessed cross-trait associations, expression quantitative trait loci in subcutaneous adipose, and biological pathways of nearby genes. Eight of the nine loci were also associated (p < 1 × 10^-4) with at least one obesity or lipid trait. Candidate genes include PRKAR2A, PTH1R, and HDAC9, which have been suggested to play roles in adipocyte differentiation or bone marrow adipose tissue. Taken together, these findings provide further insights into the processes that influence circulating adiponectin levels.

Maternal and fetal genetic effects on birth weight and their relevance to cardio-metabolic risk factors

Birth weight variation is influenced by fetal and maternal genetic and non-genetic factors, and has been reproducibly associated with future cardio-metabolic health outcomes. In expanded genome-wide association analyses of own birth weight (n = 321,223) and offspring birth weight (n = 230,069 mothers), we identified 190 independent association signals (129 of which are novel). We used structural equation modeling to decompose the contributions of direct fetal and indirect maternal genetic effects, then applied Mendelian randomization to illuminate causal pathways. For example, both indirect maternal and direct fetal genetic effects drive the observational relationship between lower birth weight and higher later blood pressure: maternal blood pressure-raising alleles reduce offspring birth weight, but only direct fetal effects of these alleles, once inherited, increase later offspring blood pressure. Using maternal birth weight-lowering genotypes to proxy for an adverse intrauterine environment provided no evidence that it causally raises offspring blood pressure, indicating that the inverse birth weight-blood pressure association is attributable to genetic effects, and not to intrauterine programming.

Regulation of inflammation during gestation and birth outcomes: Inflammatory cytokine balance predicts birth weight and length

OBJECTIVES

The maternal environment during gestation influences offspring health at birth and throughout the life course. Recent research has demonstrated that endogenous immune processes such as dysregulated inflammation adversely impact birth outcomes, increasing the risk for preterm birth and restricted fetal growth. Prior analyses examining this association suggest a relationship between maternal C-reactive protein (CRP), a summary measure of inflammation, and offspring anthropometric outcomes. This study investigates pro- and anti-inflammatory cytokines, and their ratio, to gain deeper insight into the regulation of inflammation during pregnancy.

METHODS

IL6, IL10, TNFɑ, and CRP were quantified in dried blood spots collected in the early third trimester (mean = 29.9 weeks) of 407 pregnancies in Metropolitan Cebu, Philippines. Relationships between these immune markers and offspring anthropometrics (birth weight, length, head circumference, and sum of skinfold thicknesses) were evaluated using multivariate regression analyses. Ratios of pro- to anti-inflammatory cytokines were generated.

RESULTS

Higher maternal IL6 relative to IL10 was associated with reduced offspring weight and length at birth. Individual cytokines did not predict birth outcomes.

CONCLUSIONS

Consistent with the idea that the relative balance of cytokines with pro- and anti-inflammatory effects is a key regulator of inflammation in pregnancy, the IL6:IL10 ratio, but neither cytokine on its own, predicted offspring birth outcomes. Our findings suggest that prior reports of association between CRP and fetal growth may reflect, in part, the balance between pro- and anti-inflammatory cytokines, and that the gestational environment is significantly shaped by cytokine imbalance.

Ankle brachial index (ABI) in a cohort of older women in the Philippines: Prevalence of peripheral artery disease and predictors of ABI

OBJECTIVE

Cardiovascular disease (CVD) is rising in low and middle-income countries, but studies of CVD epidemiology in such settings often focus on risk factors rather than measures of disease progression. Here we use the ankle brachial index (ABI) to assess the prevalence of peripheral artery disease (PAD) among older women living in Metropolitan Cebu, Philippines, and relationships between ABI and CVD risk factors and body composition.

METHODS

ABI was measured using the Doppler technique in 538 female participants in the 2015 Cebu Longitudinal Health and Nutrition Survey (mean age 58 years, range 47-78 years). ABI was related to a panel of CVD risk factors measured in 2005 and 2012, and to 2012 body composition measures.

RESULTS

The prevalence of PAD (1.8%) was among the lowest reported in any comparably-aged sample, and only 9.9% of participants had an ABI indicating borderline PAD risk. Smoking (P < 0.011) and use of CVD medications (P < 0.0001) predicted lower ABI (indicating higher PAD risk), which was also lower in relation to 2012 systolic blood pressure (P < 0.054). ABI was unrelated to other CVD risk factors. An apparent protective relationship between body mass index (BMI) and ABI, noted in previous studies, was found to be confounded by protective relationships between ABI and fat free mass, height, and grip strength (all P < 0.05).

CONCLUSIONS

The prevalence of PAD is low in Cebu Longitudinal Health and Nutrition Survey participants, and ABI was related to few CVD risk factors. Past reports of lower PAD risk in relation to BMI may reflect confounding by lean mass, which has protective relationships with ABI.

Time-use Profiles, Chronic Role Overload, and Women's Body Weight Trajectories from Middle to Later Life in the Philippines

Although chronic life strain is often found to be associated with adverse health outcomes, empirical research is lacking on the health implications of persistent role overload that many women around the world are subject to, the so-called double burden of work and family responsibilities. Using data from the Cebu Longitudinal Health and Nutrition Survey (1994-2012), we examined the linkage between time-use profiles and body mass index (BMI) trajectories for Filipino women over an 18-year span. Out of the four classes of women with differential levels of a combination of work and family duties, the group with the heaviest double burden has the highest average BMI. In addition, those who have remained in this class for three or more waves of data not only have higher BMI on average but also have experienced the steepest rate of increase in BMI upon transition from midlife to old age.

How Overweight and Obesity Relate to the Development of Functional Limitations among Filipino Women

As life expectancy and obesity increase in low and middle-income countries, the relationship of weight status to functional outcomes in older adults in these settings requires attention. We examined how overweight (BMI > 25 kg/m²), obesity (BMI > 30 kg/m²), and high waist circumference (WC > 80 cm) related to grip strength, timed up-and-go, and development of limitations in mobility, activities of daily living (ADL), and instrumental activities of daily living (IADL) among Filipino women. We analyzed data from seven rounds of the Cebu Longitudinal Health and Nutrition Survey (1994, n = 2279 to 2015, n = 1568, age 49–78 years) to examine how women’s reports of functional limitations related to their prior WC, and how their grip strength and timed up-and-go related to concurrently measured overweight and obesity, adjusted for age, socioeconomic status, and urbanicity. High WC was associated with higher odds of subsequent mobility and IADL limitations. Chronic disease morbidity (sum of self-reported arthritis, high blood pressure, heart disease, diabetes, and cancer) fully mediated the association of high WC with ADL and IADL limitations, but not physical/mobility limitations. Longer up-and-go times, and higher grip strength were related to overweight and obesity. Results emphasize the need for obesity prevention to reduce chronic diseases and maintain good functional status as women age.

Seventeen-Year Changes in Body Mass Index, Waist Circumference, Elevated Blood Pressure, and Diabetes Phenotypes in a Cohort of Filipino Women

Obesity, hypertension, and diabetes have risen dramatically in Asia, but few cohort studies track age and secular trends in these conditions. We use Cebu (The Philippines) Longitudinal Health and Nutrition survey data to document 1998 to 2015 prevalence and co-occurrence of body mass index (BMI; >25 kg/m²), high waist circumference (WC; >80 cm), elevated blood pressure (EBP; systolic ⩾130 or diastolic ⩾85 mm Hg), and type 2 diabetes among ~2000 women aged 29 to 62 years in 1998; and identify their relationship to community, household, and individual factors using longitudinal logistic regression. Prevalence (1998-2015) rates were 35% to 49%, BMI >25 kg/m²; 32% to 58% high WC; 21% to 59% EBP; and 2% to 14% diabetes. Only 20% of women had none of these conditions in 2015. Diabetes was strongly driven by age and secular trends in high WC related to higher socioeconomic status and urbanization. Hypertension increased with age in lower socioeconomic status rural and more affluent urban women. Results underscore the continuing need for public health measures to prevent obesity and to identify and treat hypertension and diabetes.

Genome-wide physical activity interactions in adiposity - A meta-analysis of 200,452 adults

Physical activity (PA) may modify the genetic effects that give rise to increased risk of obesity. To identify adiposity loci whose effects are modified by PA, we performed genome-wide interaction meta-analyses of BMI and BMI-adjusted waist circumference and waist-hip ratio from up to 200,452 adults of European (n = 180,423) or other ancestry (n = 20,029). We standardized PA by categorizing it into a dichotomous variable where, on average, 23% of participants were categorized as inactive and 77% as physically active. While we replicate the interaction with PA for the strongest known obesity-risk locus in the FTO gene, of which the effect is attenuated by ~30% in physically active individuals compared to inactive individuals, we do not identify additional loci that are sensitive to PA. In additional genome-wide meta-analyses adjusting for PA and interaction with PA, we identify 11 novel adiposity loci, suggesting that accounting for PA or other environmental factors that contribute to variation in adiposity may facilitate gene discovery.

Prenatal care and child growth and schooling in four low- and medium-income countries

BACKGROUND

The effectiveness of prenatal care for improving birth and subsequent child outcomes in low-income countries remains controversial, with much of the evidence to date coming from high-income countries and focused on early-life outcomes. We examined associations between prenatal care visits and birth weight, height-for-age at 24 months and attained schooling in four low- and middle-income countries.

METHODS

We pooled data from prospective birth-cohort studies from Brazil, Guatemala, Philippines and South Africa. We created a prenatal care utilization index based on the number and timing of prenatal visits. Associations were examined between this index and birth weight, height-for-age at 24 months, and highest attained schooling grade until adulthood.

RESULTS

Among 7203 individuals in the analysis, 68.9% (Philippines) to 96.7% (South Africa) had at least one prenatal care visit, with most having at least four visits. Over 40% of Brazilians and Guatemalans had their first prenatal visit in the first trimester, but fewer Filipinos (13.9%) and South Africans (19.8%) did so. Prenatal care utilization was not significantly associated with birth weight (p>0.05 in pooled data). Each unit increase in the prenatal care utilization index was associated with 0.09 (95% CI 0.04 to 0.15) higher height-for-age z-score at 24 months and with 0.26 (95% CI 0.17 to 0.35) higher schooling grades attained. Although there was some heterogeneity and greater imprecision across sites, the results were qualitatively similar among the four different populations.

CONCLUSIONS

While not related to birth weight, prenatal care utilization was associated with important outcomes later in life, specifically higher height-for-age at 24 months and higher attained school grades. These results suggest the relevance of prenatal care visits for human capital outcomes important over the lifecycle.

Early life infection, but not breastfeeding, predicts adult blood telomere lengths in the Philippines

OBJECTIVES

Telomeres are repetitive DNA at chromosomes ends that shorten with age due to cellular replication and oxidative stress. As telomeres shorten, this can eventually place limits on cell replication and contribute to senescence. Infections are common during early development and activate cellular immune responses that involve clonal expansion and oxidative stress. As such, a high infectious disease burden might shorten blood telomere length (BTL) and accelerate the pace of immune senescence.

METHODS

To test this, BTL measured in young adults (21.7 ± 0.3 years old) from the Philippines (N = 1,759) were linked to prospectively collected early life data on infectious burden.

RESULTS

As predicted, increased early life diarrheal prevalence was associated with shorter adult BTL. The association was most marked for infections experienced from 6 to 12 months, which corresponds with weaning and maximal diarrheal burden. A standard deviation increase in infections at 6-12 m predicts a 45 bp decrease in BTL, equivalent to 3.3 years of adult telomeric aging in this population. Contrary to expectations, breastfeeding duration was not associated with BTL, nor did effects vary by sex.

CONCLUSIONS

These findings show that infancy diarrheal disease predicts a marker of cellular aging in adult immune cells. These findings suggest that early life infectious burden may influence late life health, or alternatively, that short TL in early life increases infectious disease susceptibility.

Genome-wide associations for birth weight and correlations with adult disease

Birth weight (BW) has been shown to be influenced by both fetal and maternal factors and in observational studies is reproducibly associated with future risk of adult metabolic diseases including type 2 diabetes (T2D) and cardiovascular disease. These life-course associations have often been attributed to the impact of an adverse early life environment. Here, we performed a multi-ancestry genome-wide association study (GWAS) meta-analysis of BW in 153,781 individuals, identifying 60 loci where fetal genotype was associated with BW (P < 5 × 10-8). Overall, approximately 15% of variance in BW was captured by assays of fetal genetic variation. Using genetic association alone, we found strong inverse genetic correlations between BW and systolic blood pressure (Rg = -0.22, P = 5.5 × 10-13), T2D (Rg = -0.27, P = 1.1 × 10-6) and coronary artery disease (Rg = -0.30, P = 6.5 × 10-9). In addition, using large -cohort datasets, we demonstrated that genetic factors were the major contributor to the negative covariance between BW and future cardiometabolic risk. Pathway analyses indicated that the protein products of genes within BW-associated regions were enriched for diverse processes including insulin signalling, glucose homeostasis, glycogen biosynthesis and chromatin remodelling. There was also enrichment of associations with BW in known imprinted regions (P = 1.9 × 10-4). We demonstrate that life-course associations between early growth phenotypes and adult cardiometabolic disease are in part the result of shared genetic effects and identify some of the pathways through which these causal genetic effects are mediated.

Early life height and weight production functions with endogenous energy and protein inputs

We examine effects of protein and energy intakes on height and weight growth for children between 6 and 24 months old in Guatemala and the Philippines. Using instrumental variables to control for endogeneity and estimating multiple specifications, we find that protein intake plays an important and positive role in height and weight growth in the 6-24 month period. Energy from other macronutrients, however, does not have a robust relation with these two anthropometric measures. Our estimates indicate that in contexts with substantial child undernutrition, increases in protein-rich food intake in the first 24 months can have important growth effects, which previous studies indicate are related significantly to a range of outcomes over the life cycle.

Implications of Changes in Family Structure and Composition for the Psychological Well-Being of Filipino Women in Middle and Later Years

The health implications of multigenerational coresidence for older adults is a well-researched topic in the aging literature. Much less is known of its impact for women in midlife. We used data from the Cebu Longitudinal Health and Nutrition Study (2002, 2005, 2007, and 2012) to study the influence of transitions in multigenerational household composition on depressive symptoms for women in midlife transitioning into old age. Our initial analysis showed little effect when we use the conventional classification of nuclear versus extended family and transition in and out of extended family. When we described shifts in the family environment by compositional changes, that is, change in the presence and absence of particular family members, we found significant association between depressive symptoms and two types of role transitions: the loss of a spouse in the household and the entry and exit of grandchildren in the household.

Adiposity and Chronic Inflammation in Young Women Predict Inflammation during Normal Pregnancy in the Philippines

BACKGROUND

Rates of overweight and obesity are on the rise globally, and excess adipose tissue may contribute to elevations in inflammation during pregnancy, leading to pregnancy complications and adverse birth outcomes.

OBJECTIVE

The purpose of this study was to evaluate adiposity and inflammation in young women as predictors of inflammation in the third trimester of pregnancy in a community-based sample of healthy women.

METHODS

Female participants (24-30 y) in a prospective observational cohort study (Cebu Longitudinal Health and Nutrition Survey) were contacted between 2009 and 2014 to identify new pregnancies. A total of 309 women provided data from 409 pregnancies. An in-home interview was scheduled for the third trimester to collect pregnancy information, anthropometric measurements, and a blood sample. Circulating C-reactive protein (CRP) was measured with a high-sensitivity immunoassay. Data collected from assessments in 2005 and 2009 were used to assess body mass index (BMI) and CRP in young adulthood, before pregnancy. Robust regression models were implemented to evaluate BMI and CRP in young adulthood as predictors of pregnancy CRP.

RESULTS

Pre-pregnancy BMI was a stronger predictor of third-trimester circulating CRP than BMI in the third trimester. No association was found between pregnancy weight gain and CRP. Pre-pregnancy CRP was a significant predictor of CRP in pregnancy, independent of BMI.

CONCLUSIONS

Levels of overweight/obesity and inflammation in young adulthood, before pregnancy, are important predictors of inflammation in the third trimester of pregnancy. These results may have implications for addressing the growing concern about the contribution of obesity to adverse birth outcomes, and they suggest that factors that influence the regulation of inflammation, before pregnancy and independent of adiposity, may be important in shaping the inflammatory response to pregnancy.

No association between blood telomere length and longitudinally assessed diet or adiposity in a young adult Filipino population

PURPOSE

Telomeres, DNA-protein structures that cap and protect chromosomes, are thought to shorten more rapidly when exposed to chronic inflammation and oxidative stress. Diet and nutritional status may be a source of inflammation and oxidative stress. However, relationships between telomere length (TL) and diet or adiposity have primarily been studied cross-sectionally among older, overweight/obese populations and yielded inconsistent results. Little is known about the relationship between diet or body composition and TL among younger, low- to normal-weight populations. It also remains unclear how cumulative exposure to a specific diet or body composition during the years of growth and development, when telomere attrition is most rapid, may be related to TL in adulthood.

METHODS

In a sample of 1459 young adult Filipinos, we assessed the relationship between blood TL at ages 20.8-22.5 and measures of BMI z-score, waist circumference, and diet collected between the ages of 8.5 and 22.5. TL was measured using monochrome multiplex quantitative PCR, and diet was measured using multiple 24-h recalls.

RESULTS

We found no associations between blood TL and any of the measures of adiposity or between blood TL and the seven dietary factors examined: processed meats, fried/grilled meats and fish, non-fried fish, coconut oil, fruits and vegetables, bread and bread products, and sugar-sweetened beverages.

CONCLUSIONS

Considering the inconsistencies in the literature and our null results, small differences in body composition and consumption of any single pro- or anti-inflammatory dietary component may not by themselves have a meaningful impact on telomere integrity, or the impact may differ across distinct ecological circumstances.

Maternal characteristics associated with milk leptin content in a sample of Filipino women and associations with infant weight for age

BACKGROUND

Human milk contains many metabolic hormones that may influence infant growth. Milk leptin is positively associated with maternal adiposity and inversely associated with infant growth. Most research has been conducted in populations with higher leptin levels; it is not well understood how milk leptin may vary in lean populations or the associations that reduced leptin may have with infant size for age. It is also largely unknown if associations between maternal body composition and milk leptin persist past 1 year of age.

OBJECTIVES

We investigated the association between maternal body composition and milk leptin content in a sample of lean Filipino women and the association between milk leptin content and infant size for age.

METHODS

Milk samples were collected at in-home visits from 113 mothers from Cebu, Philippines. Milk leptin content was measured using EIA techniques; anthropometric data, dietary recalls, and household information were also collected.

RESULTS

Mean ± standard deviation (SD) milk leptin in this sample was 300.7 ± 293.6 pg/mL, among the lowest previously reported. Mean ± SD maternal percentage body fat was 24.8% ± 3.5%. Mean ± SD infant age was 9.9 ± 7.0 months, and mean ± SD weight for age z-score was -0.98 ± 1.06. Maternal percentage body fat was a significant, positive predictor of milk leptin content. Milk leptin was a significant, inverse predictor of infant weight and body mass index z-scores in infants 1 year old or younger.

CONCLUSION

The association between maternal body composition, milk leptin, and infant growth persists in mothers with lean body composition. Milk leptin is not associated with growth in older infants.

C-reactive protein response to influenza vaccination as a model of mild inflammatory stimulation in the Philippines

BACKGROUND

C-reactive protein (CRP) is increasingly measured as a marker of systemic inflammation that predicts elevated risk for cardiovascular disease. Influenza vaccination is a mild pro-inflammatory stimulus, and the CRP response to vaccination may provide additional information on individual differences in inflammatory response and risk for disease.

AIM

To document the pattern of CRP response to influenza vaccination among a large sample of older women in the Philippines. The Philippines exemplifies current global trends toward increasing rates of overweight/obesity, but also maintains relatively high rates of infectious disease. The secondary aim of the study is to investigate the impact of infectious symptoms on the pattern of response to vaccination.

METHODS

A community-based sample of 934 women (mean age=55.4 years) received the influenza vaccine. CRP was assessed at baseline and 72h post-vaccination. Descriptive, non-parametric, and parametric analyses were implemented to assess the magnitude of CRP response, and to investigate whether responses were associated with baseline CRP or the presence of infectious symptoms prior to vaccination.

RESULTS

Influenza vaccination resulted in a statistically significant CRP response of 0.35mg/L (p<0.001), representing a 30.2% increase from baseline. For individuals with symptoms of infectious disease at baseline, the CRP response was smaller (12.9%) and not statistically significant (p=0.77). Lower CRP at baseline was associated with larger CRP response to vaccination in the entire sample, and among participants without recent symptoms of infection.

CONCLUSIONS

Influenza vaccination produces a mild CRP response in the Philippines. This study extends prior research in US and European populations validating influenza vaccination as an in vivo model for investigating the dynamics of inflammation, but also raises potential complications in settings where rates of infectious disease are elevated.

A meta-analysis of genome-wide association studies for adiponectin levels in East Asians identifies a novel locus near WDR11-FGFR2

Blood levels of adiponectin, an adipocyte-secreted protein correlated with metabolic and cardiovascular risks, are highly heritable. Genome-wide association (GWA) studies for adiponectin levels have identified 14 loci harboring variants associated with blood levels of adiponectin. To identify novel adiponectin-associated loci, particularly those of importance in East Asians, we conducted a meta-analysis of GWA studies for adiponectin in 7827 individuals, followed by two stages of replications in 4298 and 5954 additional individuals. We identified a novel adiponectin-associated locus on chromosome 10 near WDR11-FGFR2 (P = 3.0 × 10(-14)) and provided suggestive evidence for a locus on chromosome 12 near OR8S1-LALBA (P = 1.2 × 10(-7)). Of the adiponectin-associated loci previously described, we confirmed the association at CDH13 (P = 6.8 × 10(-165)), ADIPOQ (P = 1.8 × 10(-22)), PEPD (P = 3.6 × 10(-12)), CMIP (P = 2.1 × 10(-10)), ZNF664 (P = 2.3 × 10(-7)) and GPR109A (P = 7.4 × 10(-6)). Conditional analysis at ADIPOQ revealed a second signal with suggestive evidence of association only after conditioning on the lead SNP (Pinitial = 0.020; Pconditional = 7.0 × 10(-7)). We further confirmed the independence of two pairs of closely located loci (<2 Mb) on chromosome 16 at CMIP and CDH13, and on chromosome 12 at GPR109A and ZNF664. In addition, the newly identified signal near WDR11-FGFR2 exhibited evidence of association with triglycerides (P = 3.3 × 10(-4)), high density lipoprotein cholesterol (HDL-C, P = 4.9 × 10(-4)) and body mass index (BMI)-adjusted waist-hip ratio (P = 9.8 × 10(-3)). These findings improve our knowledge of the genetic basis of adiponectin variation, demonstrate the shared allelic architecture for adiponectin with lipids and central obesity and motivate further studies of underlying mechanisms.

Do environments in infancy moderate the association between stress and inflammation in adulthood? Initial evidence from a birth cohort in the Philippines

Chronic inflammation is a potentially important pathway through which psychosocial stressors increase risk for cardiovascular disease. However, prior research on stress and inflammation has been conducted almost exclusively in high income, industrialized populations with low levels of infectious disease. In this study we test the hypothesis that psychosocial stressors are associated with elevated concentrations of C-reactive protein (CRP) among young adults in the Philippines (n=1622), who have grown up in an ecological and epidemiological setting that differs substantially from that of the US. In addition, we apply a developmental, ecological perspective to consider whether microbial and nutritional environments in infancy alter patterns of association between stressors and CRP. Data come from the Cebu Longitudinal Health and Nutrition Survey, a prospective cohort study that began collecting data in 1983-1984 when participants were in utero. A series of regression models indicate trends toward significant interactions between perceived stress and environmental factors in infancy, including exposure to animal feces, season of birth, and birth weight. Parental absence in childhood was a significant predictor of CRP in adulthood in interaction with exposure to animal feces in infancy. Positive associations between stressors and CRP were only evident for individuals with lower levels of microbial exposure in infancy, or lower birth weight. These results suggest that early environments influence the development of inflammatory phenotypes in ways that moderate sensitivity to psychosocial stressors in adulthood, and they underscore the value of a comparative, developmental approach to research on social environments, inflammation, and disease.

The impact of early nutrition on health: key findings from the Cebu Longitudinal Health and Nutrition Survey (CLHNS)

INTRODUCTION

The Philippines' Cebu Longitudinal Health and Nutrition Survey (CLHNS) is one of the longest running birth cohort studies in Southeast Asia. This paper illustrates the pathways through which maternal and infant nutrition influence later health outcomes using selected CLHNS findings.

METHODS

The CLHNS initially examined the determinants and consequences of low birth weight and early nutrition on child growth and development. It has since expanded to study other health, nutrition, and demographic issues in the life course of the cohort participants such as the consequences of early nutrition on adult health.

RESULTS

CLHNS findings have documented important effects of poor maternal nutrition beyond impaired foetal growth (manifested through low birth weight). Mothers who had lower energy intakes and poorer nutritional status during pregnancy had offsprings who were at risk of having higher blood pressure measurements in adolescence. Infants born small at birth were not only more likely to be stunted through adolescence, but were also at greater risk of cardiovascular disease later in life. Among the males, those born thin at birth and have high BMI in adulthood had increased risk of elevated systolic blood pressure. Early infant feeding also had long-term effects on health. Breastfeeding not only protected against morbidity and stunting in childhood, but also lowered the risk of insulin resistance and high triglyceride levels in adulthood among the males. Delayed complementary feeding was associated a with lower risk of overweight in young adulthood. An intergenerational matrilineal effect was also observed among the participants, with maternal birth weight being positively associated with offspring birth weight.

CONCLUSION

The CLHNS findings support the WHO recommendations for exclusive breastfeeding until six months, timely introduction of complementary foods, and continued breastfeeding until two years. Since child nutrition begins in utero, programs should focus on improving maternal nutrition during pregnancy to minimise the risk of low birth weight.

Depressive symptoms are not associated with inflammation in younger and older adults in the Philippines

Depression is not associated with inflammation among adults in the Philippines, in contrast to prior research in the US. These results suggest that higher levels of microbial exposure in the Philippines may promote the development of immuno-regulatory pathways that prevent the emergence of a relationship between depression and inflammation.

Depression is positively associated with chronic inflammation in industrialized settings with low burdens of infectious disease, but the pattern of association in environments with higher levels of microbial exposure is not known. We measured C-reactive protein (CRP) and interleukin 6 (IL6) in community-based samples of young adults (20–22 years) and older women (35–69 years) in the Philippines. Concentrations of CRP and IL6 were low, and bivariate and multivariate regression analyses indicated no associations between depressive symptoms and inflammation in either sample. Results are interpreted in light of prior research indicating that higher levels of microbial exposure in infancy have lasting effects on the regulation of inflammation, and may prevent the emergence of a relationship between depression and inflammation in adulthood.

Novel loci for adiponectin levels and their influence on type 2 diabetes and metabolic traits: a multi-ethnic meta-analysis of 45,891 individuals

Circulating levels of adiponectin, a hormone produced predominantly by adipocytes, are highly heritable and are inversely associated with type 2 diabetes mellitus (T2D) and other metabolic traits. We conducted a meta-analysis of genome-wide association studies in 39,883 individuals of European ancestry to identify genes associated with metabolic disease. We identified 8 novel loci associated with adiponectin levels and confirmed 2 previously reported loci (P = 4.5×10(-8)-1.2×10(-43)). Using a novel method to combine data across ethnicities (N = 4,232 African Americans, N = 1,776 Asians, and N = 29,347 Europeans), we identified two additional novel loci. Expression analyses of 436 human adipocyte samples revealed that mRNA levels of 18 genes at candidate regions were associated with adiponectin concentrations after accounting for multiple testing (p<3×10(-4)). We next developed a multi-SNP genotypic risk score to test the association of adiponectin decreasing risk alleles on metabolic traits and diseases using consortia-level meta-analytic data. This risk score was associated with increased risk of T2D (p = 4.3×10(-3), n = 22,044), increased triglycerides (p = 2.6×10(-14), n = 93,440), increased waist-to-hip ratio (p = 1.8×10(-5), n = 77,167), increased glucose two hours post oral glucose tolerance testing (p = 4.4×10(-3), n = 15,234), increased fasting insulin (p = 0.015, n = 48,238), but with lower in HDL-cholesterol concentrations (p = 4.5×10(-13), n = 96,748) and decreased BMI (p = 1.4×10(-4), n = 121,335). These findings identify novel genetic determinants of adiponectin levels, which, taken together, influence risk of T2D and markers of insulin resistance.

Microbial exposures in infancy predict levels of the immunoregulatory cytokine interleukin-4 in Filipino young adults

OBJECTIVES

Infancy represents a window of development during which long-term immunological functioning can be influenced. In this study, we evaluate proxies of microbial exposures in infancy as predictors of interleukin-4 (IL-4) in young adulthood. IL-4 is an immunoregulatory cytokine that plays a role in the pathogenesis of atopic and allergic diseases.

METHODS

Data were obtained from 1,403 participants in the Cebu Longitudinal Health and Nutrition Survey, an ongoing population-based study in the Philippines. Relationships between microbial and nutritional environments in infancy and plasma IL-4 concentrations in adulthood were evaluated using tobit regression models.

RESULTS

Having older siblings and more episodes of respiratory illness in infancy significantly predicted lower concentrations of plasma IL-4 in adulthood. Unexpectedly, more episodes of diarrheal illness in infancy were associated with higher IL-4 in adulthood. Interactions between a composite household pathogen exposure score and the duration of exclusive breastfeeding approached significance. This interaction showed that the negative association between household pathogen exposure in infancy and adult IL-4 was only significant for individuals who had been exclusively breastfed for a short duration of time. Finally, currently living in an urban household was unexpectedly, negatively associated with adult IL-4. Associations were independent of early nutrition, socioeconomic status (SES), and urbanicity, as well as current measures of infection, body fat, SES, and smoking.

CONCLUSIONS

This study builds on a growing body of literature demonstrating that early ecological conditions have long-term effects on human biology by providing evidence that multiple proxies of microbial exposures in infancy are associated with adult IL-4.

Population-specific coding variant underlies genome-wide association with adiponectin level

Adiponectin is a protein hormone that can affect major metabolic processes including glucose regulation and fat metabolism. Our previous genome-wide association (GWA) study of circulating plasma adiponectin levels in Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS) detected a 100 kb two-SNP haplotype at KNG1-ADIPOQ associated with reduced adiponectin (frequency = 0.050, P = 1.8 × 10(-25)). Subsequent genotyping of CLHNS young adult offspring detected an uncommon variant [minor allele frequency (MAF) = 0.025] located ~800 kb from ADIPOQ that showed strong association with lower adiponectin levels (P = 2.7 × 10(-15), n = 1695) and tagged a subset of KNG1-ADIPOQ haplotype carriers with even lower adiponectin levels. Sequencing of the ADIPOQ-coding region detected variant R221S (MAF = 0.015, P = 2.9 × 10(-69)), which explained 17.1% of the variance in adiponectin levels and largely accounted for the initial GWA signal in Filipinos. R221S was not present in 12 514 Europeans with previously sequenced exons. To explore the mechanism of this substitution, we re-measured adiponectin level in 20 R221S offspring carriers and 20 non-carriers using two alternative antibodies and determined that the presence of R221S resulted in artificially low quantification of adiponectin level using the original immunoassay. These data provide an example of an uncommon variant responsible for a GWA signal and demonstrate that genetic associations with phenotypes measured by antibody-based quantification methods can be affected by uncommon coding SNPs residing in the antibody target region.

Single-nucleotide polymorphisms at five loci are associated with C-reactive protein levels in a cohort of Filipino young adults

C-reactive protein (CRP) is a component of nonspecific immune defense and is a reliable marker of low-grade inflammation involved in obesity, type 2 diabetes and cardiovascular disease. Genome-wide association studies in middle-aged and elderly populations, predominantly of European descent, demonstrated associations of CRP levels with single-nucleotide polymorphisms (SNPs) at several loci. To examine whether the variants identified are replicated in Filipino young adults, we applied Tobit regression models to study the association of plasma CRP with 12 SNPs at seven loci in a cohort of 1691 Filipino young adults (aged 21.5±0.3 years) from the Cebu Longitudinal Health and Nutrition Survey. SNPs in or near CRP (P=3.2 × 10(-11)), HNF1A, IL6R, APOE-APOC1 and LEPR showed significant associations (P<0.05) and together explained 4.8% of the total variation in CRP. Modest interactions were observed between LEPR-rs1892534 and waist circumference (uncorrected P(interaction)=0.020) and between APOE-rs769449 and pathogen exposure (uncorrected P(interaction)=0.0073) in models predicting CRP. Our results demonstrated that variants in several loci are significantly associated with plasma CRP in Filipino young adults, suggesting shared genetic influences on circulating CRP across populations and age groups.

Infant-feeding patterns and cardiovascular risk factors in young adulthood: data from five cohorts in low- and middle-income countries

BACKGROUND

Infant-feeding patterns may influence lifelong health. This study tested the hypothesis that longer duration of breastfeeding and later introduction of complementary foods in infancy are associated with reduced adult cardiovascular risk.

METHODS

Data were pooled from 10 912 subjects in the age range of 15-41 years from five prospective birth-cohort studies in low-/middle-income countries (Brazil, Guatemala, India, Philippines and South Africa). Associations were examined between infant feeding (duration of breastfeeding and age at introduction of complementary foods) and adult blood pressure (BP), plasma glucose concentration and adiposity (skinfolds, waist circumference, percentage body fat and overweight/obesity). Analyses were adjusted for maternal socio-economic status, education, age, smoking, race and urban/rural residence and infant birth weight.

RESULTS

There were no differences in outcomes between adults who were ever breastfed compared with those who were never breastfed. Duration of breastfeeding was not associated with adult diabetes prevalence or adiposity. There were U-shaped associations between duration of breastfeeding and systolic BP and hypertension; however, these were weak and inconsistent among the cohorts. Later introduction of complementary foods was associated with lower adult adiposity. Body mass index changed by -0.19 kg/m(2) [95% confidence interval (CI) -0.37 to -0.01] and waist circumference by -0.45 cm (95% CI -0.88 to -0.02) per 3-month increase in age at introduction of complementary foods.

CONCLUSIONS

There was no evidence that longer duration of breastfeeding is protective against adult hypertension, diabetes or overweight/adiposity in these low-/middle-income populations. Further research is required to determine whether 'exclusive' breastfeeding may be protective. Delaying complementary foods until 6 months, as recommended by the World Health Organization, may reduce the risk of adult overweight/adiposity, but the effect is likely to be small.

Genome-wide association study for adiponectin levels in Filipino women identifies CDH13 and a novel uncommon haplotype at KNG1-ADIPOQ

Adiponectin is an adipocyte-secreted protein involved in a variety of metabolic processes, including glucose regulation and fatty acid catabolism. We conducted a genome-wide association study to investigate the genetic loci associated with plasma adiponectin in 1776 unrelated Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS). Our strongest signal for adiponectin mapped to the gene CDH13 (rs3865188, P ≤ 7.2 × 10(-16)), which encodes a receptor for high-molecular-weight forms of adiponectin. Strong association was also detected near the ADIPOQ gene (rs864265, P = 3.8 × 10(-9)) and at a novel signal 100 kb upstream near KNG1 (rs11924390, P = 7.6 × 10(-7)). All three signals were also observed in 1774 young adult CLHNS offspring and in combined analysis including all 3550 mothers and offspring samples (all P ≤ 1.6 × 10(-9)). An uncommon haplotype of rs11924390 and rs864265 (haplotype frequency = 0.050) was strongly associated with lower adiponectin compared with the most common C-G haplotype in both CLHNS mothers (P = 1.8 × 10(-25)) and offspring (P = 8.7 × 10(-32)). Comprehensive imputation of 2653 SNPs in a 2 Mb region using as reference combined CHB, JPT and CEU haplotypes from the 1000 Genomes Project revealed no variants that perfectly tagged this haplotype. Our findings provide the first genome-wide significant evidence of association with plasma adiponectin at the CDH13 locus and identify a novel uncommon KNG1-ADIPOQ haplotype strongly associated with adiponectin levels in Filipinos.

Genome-wide association study of homocysteine levels in Filipinos provides evidence for CPS1 in women and a stronger MTHFR effect in young adults

Plasma homocysteine (Hcy) level is associated with cardiovascular disease and may play an etiologic role in vascular damage, a precursor for atherosclerosis. We performed a genome-wide association study for Hcy in 1786 unrelated Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS). The most strongly associated single-nucleotide polymorphism (SNP) (rs7422339, P = 4.7 x 10(-13)) encodes Thr1405Asn in the gene CPS1 and explained 3.0% of variation in the Hcy level. The widely studied MTHFR C677T SNP (rs1801133) was also highly significant (P = 8.7 x 10(-10)) and explained 1.6% of the trait variation. We also genotyped these two SNPs in 1679 CLHNS young adult offspring. The MTHFR C677T SNP was strongly associated with Hcy (P = 1.9 x 10(-26)) and explained approximately 5.1% of the variation in the offspring. In contrast, the CPS1 variant was significant only in females (P = 0.11 in all; P = 0.0087 in females). Combined analysis of all samples confirmed that the MTHFR variant was more strongly associated with Hcy in the offspring (interaction P = 1.2 x 10(-5)). Furthermore, although there was evidence for a positive synergistic effect between the CPS1 and MTHFR SNPs in the offspring (interaction P = 0.0046), there was no significant evidence for an interaction in the mothers (P = 0.55). These data confirm a recent finding that CPS1 is a locus influencing Hcy levels in women and suggest that genetic effects on Hcy may differ across developmental stages.

Development and validation of the Infant Feeding Style Questionnaire

This study describes and validates the Infant Feeding Style Questionnaire (IFSQ), a self-report instrument designed to measure feeding beliefs and behaviors among mothers of infants and young children. Categorical confirmatory factor analysis was used to estimate latent factors for five feeding styles, laissez-faire, restrictive, pressuring, responsive and indulgent, and to validate that items hypothesized a priori as measures of each style yielded well-fitting models. Models were tested and iteratively modified to determine the best fitting model for each of 13 feeding style sub-constructs, using a sample of 154 low-income African-American mothers of infants aged 3-20 months in North Carolina. With minor changes, models were confirmed in an independent sample of 150 African-American first-time mothers, yielding a final instrument with 39 questions on maternal beliefs, 24 questions on behaviors and an additional 20 behavioral items pertaining to solid feeding for infants over 6 months of age. Internal reliability measures for the sub-constructs ranged from 0.75 to 0.95. Several sub-constructs, responsive to satiety cues, pressuring with cereal, indulgent pampering and indulgent soothing, were inversely related to infant weight-for-length z-score, providing initial support for the validity of this instrument for assessing maternal feeding beliefs and behaviors that may influence infant weight outcomes.

Grandmothers, fathers, and depressive symptoms are associated with food insecurity among low-income first-time African-American mothers in North Carolina

African Americans experience household food insecurity, ie, the limited availability of nutritionally adequate and safe food, or ability to acquire acceptable foods in socially acceptable ways, at three times the rate of non-Hispanic whites. Thirty percent of all African-American children live in food-insecure households. The purpose of this study was to identify characteristics associated with household food insecurity among a high-risk postpartum population. Two-hundred six low-income, African-American mother-infant dyads were recruited through the Special Supplemental Nutrition Program for Women, Infants, and Children clinics. The six-item US Department of Agriculture food security scale was used to classify households as food secure, marginally food secure, or food insecure. Multinomial logistic regression was used to estimate the association between selected maternal/household characteristics and household food-security status. Fifty-three percent of households were food secure, 34% were marginally food secure, and 13% were food insecure. Maternal education less than college (relative risk ratio [RRR]=0.46; 95% confidence interval [CI]: 0.22 to 0.98) was inversely associated with marginal food security. Depressive symptoms (RRR=1.09; 95% CI: 1.02 to 1.16) and having the baby's father in the household (RRR=3.46; 95% CI: 1.22 to 9.82) were associated with household food insecurity, while having a grandmother in the household (RRR=0.15; 95% CI: 0.03 to 0.80) was inversely associated with experiencing household food insecurity. Findings from this study suggest that young, low-income, African-American families with only one child are particularly susceptible to experiencing household food insecurity. Intergenerational support and transfer of knowledge can be a key protective attribute among low-income African-American households.

Assessment of infant feeding styles among low-income African-American mothers: comparing reported and observed behaviors

This study's goal was to provide a detailed description of feeding styles adopted by a sample of African-American women in feeding their infants in North Carolina, and to examine the correspondence between reported and observed feeding styles. Cross-sectional semi-structured interview and videotaped data were gathered in the homes of 20 participating low-income mothers of infants aged 3-20 months. Feeding styles were characterized through a tailored coding scheme (the Infant Feeding Styles Video Coding Scheme, IFSVCS) applied to both interview and video-taped data. We found that the most frequent feeding styles identified for both interviews and videotaped observations was restrictive, but that mothers were roughly equally divided among predominantly controlling (pressuring or restrictive) and less controlling (laissez-faire or indulgent) styles across methods. However, for over 2/3 of the sample, there was a lack of correspondence between interview and video-taped feeding styles. This unique characterization and comparison of observed and reported infant feeding styles provides additional insights into parental feeding approaches among mothers of infants at high risk of obesity, and highlights the need for further study of feeding style assessment and potential impact on infant weight outcomes.

Assessing the net effect of young maternal age on birthweight

Pregnancy during adolescence presents an increased risk for low birthweight, which is attributed not only to physiologic immaturity but also to socioeconomic and behavioral risk factors associated with adolescence. The independent effect of maternal age on birthweight is difficult to ascertain because age is closely entangled with these risks. We first examined the effect of being an adolescent mother on these risk pathways and then estimated the net effect of maternal age on birthweight (weight in grams or low birthweight (<2500 g)) after controlling for these risks. We used data on 214 adolescent and 415 adult primiparae and their infants from the Cebu Longitudinal Health and Nutrition Survey, a community-based survey in Metro Cebu, Philippines. Consistent with findings from other studies, adolescents in this sample were more socioeconomically disadvantaged, had poorer nutritional status during pregnancy, and received less prenatal care than adults. Bivariate analyses showed that infants of adolescents had a lower mean birthweight and were more at risk of low birthweight compared to those born to older mothers. When socioeconomic, biological, and behavioral risk factors were controlled for, young maternal age ceased to have an effect on birthweight in grams but remained a significant predictor of low birthweight. The common pathways through which maternal age influenced both birthweight variables were through its effects on maternal height and weight-for-height during pregnancy. In the model predicting birthweight in grams the maternal age effect was further manifested through prenatal care utilization.