Differences in the heritability of growth and growth velocity during infancy and associations with FTO variants

Anthropometric prediction models of body composition in 3 to 24month old infants: a multicenter international study

BACKGROUND

Accurate assessment of body composition during infancy is an important marker of early growth. This study aimed to develop anthropometric models to predict body composition in 3-24-month-old infants from diverse socioeconomic settings and ethnic groups.

METHODS

An observational, longitudinal, prospective, multi-country study of infants from 3 to 24 months with body composition assessed at three monthly intervals using deuterium dilution (DD) and anthropometry. Linear mixed modelling was utilized to generate sex-specific fat mass (FM) and fat-free mass (FFM) prediction equations, using length(m), weight-for-length (kg/m), triceps and subscapular skinfolds and South Asian ethnicity as variables. The study sample consisted of 1896 (942 measurements from 310 girls) training data sets, 941 (441 measurements from 154 girls) validation data sets of 3-24 months from Brazil, Pakistan, South Africa and Sri Lanka. The external validation group (test) comprised 349 measurements from 250 (185 from 124 girls) infants 3-6 months of age from South Africa, Australia and India.

RESULTS

Sex-specific equations for three age categories (3-9 months; 10-18 months; 19-24 months) were developed, validated on same population and externally validated. Root mean squared error (RMSE) was similar between training, validation and test data for assessment of FM and FFM in boys and in girls. RMSPE and mean absolute percentage error (MAPE) were higher in validation compared to test data for predicting FM, however, in the assessment of FFM, both measures were lower in validation data. RMSE for test data from South Africa (M/F-0.46/0.45 kg) showed good agreement with validation data for assessment of FFM compared to Australia (M/F-0.51/0.33 kg) and India(M/F-0.77/0.80 kg).

CONCLUSIONS

Anthropometry-based FFM prediction equations provide acceptable results. Assessments based on equations developed on similar populations are more applicable than those developed from a different population.

The heritability of weight gain in infancy: A population-based twin study

BACKGROUND

Rapid weight gain during infancy is a strong predictor of childhood obesity and is affected by genetic and environmental factors. Identifying ages with low heritability will allow for targeted interventions that might be able to prevent the adverse effects of childhood obesity.

OBJECTIVES

The objective of the study is to estimate the heritability of weight gain from birth to defined ages during infancy, as well as during 6-month periods from birth to 18 months of age. We address this by leveraging large-scale computerised anthropometric data from the state-run network of well-baby clinics in Israel.

METHODS

We performed a population-based twin study. We extracted weight measurements recorded between birth to 24 months from well-baby clinics for 9388 twin pairs born in Israel between 2011 and 2015. The reported sexes of the twins were used as a proxy for their zygosity status. We estimated the heritability of the weight z-score change from birth to specific ages and during particular periods in infancy. To assess the validity of the results, we repeated the analysis in a sub-cohort of twin pairs with complete weight measurements.

RESULTS

During the first 2 years of life, heritability was lowest for birthweight (h 2 = 0.40 ± 0.11 ). Heritability for weight gain since birth was highest at 4 months (h 2 = 0.87 ± 0.13 ), and then gradually decreased until age 18 months (h 2 = 0.62 ± 0.13 ). Estimating the heritability in 6-month intervals from birth to 18 months, heritability was highest during the 6-12-month interval (h 2 = 0.84 ± 0.14 ), and was substantially lower during the subsequent 12-18-month interval (h 2 = 0.43 ± 0.16 ).

CONCLUSIONS

Heritability of weight gain decreases substantially in the second year of life, suggesting that this period could be an appropriate time for interventions for infants who are at an increased risk of childhood obesity.

Context Matters: Preliminary Evidence That the Association between Positive Affect and Adiposity in Infancy Varies in Social vs. Non-Social Situations

Previous studies have suggested that infants high in negative affect have higher levels of adiposity, arising in part via changes in nutrition (e.g., “feeding to soothe”). Few studies have examined whether positive affect shows similar or inverse associations with adiposity. The current study examined cross-sectional and longitudinal relationships between adiposity and observations of positive affect in both a social and a non-social context, using data from infants at four (n = 125) and 12 (n = 80) months of age. Our analyses did not find any cross-sectional associations between positive affect and adiposity (all p > 0.05). However, in the longitudinal analyses, positive affect in a non-social context, when observed at four months of age, was positively associated with weight-for-length at 12 months of age (zWFL; ß = 1.49, SE = 0.67, p = 0.03), while positive affect observed at four months of age in a social context was inversely associated with body fat percentage at 12 months of age (ß = −11.41, SE = 5.44, p = 0.04). These findings provide preliminary evidence that the p positive affect is related to adiposity in infancy and suggest that the direction of association (i.e., direct or inverse) may be specific to the context in which positive affect is measured. Future research should examine the role of nutritional status in any relationships between adiposity and emotion at this early stage.

The impact a Mediterranean Diet in the third trimester of pregnancy has on neonatal body fat percentage

Maternal diet during pregnancy has long been recognised as an important determinant of neonatal outcomes and child development. Infant body composition is a potentially modifiable risk factor for predicting future health and metabolic disease. Utilising the Mediterranean Diet Score, this study focused on how different levels of Mediterranean Diet adherence (MDA) in pregnancy influence body fat percentage of the infant. Information on 458 pregnant women in their third trimester of pregnancy and their infants was obtained from The ORIGINS Project. The data included MDA score, body composition measurements using infant air displacement plethysmography (PEA POD), pregnancy, and birth information. Infants born to mothers with high MDA had a body fat percentage of 11.3%, whereas infants born to mothers with low MDA had a higher body fat percentage of 13.3% (p = 0.010). When adjusted for pre-pregnancy body mass index and infant sex, a significant result remained between high vs. low MDA and infant fat mass (FM) (2.5% less FM p = 0.016). This study suggests that high MDA in pregnancy was associated with a reduced body fat percentage in the newborn. Future studies are needed to understand whether small but significant changes in FM persist throughout childhood.

Adaptive Maternal Investment in the Wild? Links between Maternal Growth Trajectory and Offspring Size, Growth, and Survival in Contrasting Environments

Life-history theory predicts that investment per offspring should correlate negatively with the quality of the environment that offspring are anticipated to encounter; parents may use their own experience as juveniles to predict this environment and may modulate offspring traits, such as growth capacity and initial size. We manipulated nutrient levels in the juvenile habitat of wild Atlantic salmon (Salmo salar) to investigate the hypothesis that the egg size that maximizes juvenile growth and survival depends on environmental quality. We also tested whether offspring traits were related to parental growth trajectory. Mothers that grew fast when young produced more offspring and smaller offspring than mothers that grew slowly to reach the same size. Despite their size disadvantage, offspring of faster-growing mothers grew faster than those of slower-growing mothers in all environments, counter to the expectation that they would be competitively disadvantaged. However, they had lower relative survival in environments where the density of older predatory/competitor fish was relatively high. These links between maternal (but not paternal) growth trajectory and offspring survival rate were independent of egg size, underscoring that mothers may be adjusting egg traits other than size to suit the environment their offspring are anticipated to face.

GWAS on longitudinal growth traits reveals different genetic factors influencing infant, child, and adult BMI

Early childhood growth patterns are associated with adult health, yet the genetic factors and the developmental stages involved are not fully understood. Here, we combine genome-wide association studies with modeling of longitudinal growth traits to study the genetics of infant and child growth, followed by functional, pathway, genetic correlation, risk score, and colocalization analyses to determine how developmental timings, molecular pathways, and genetic determinants of these traits overlap with those of adult health. We found a robust overlap between the genetics of child and adult body mass index (BMI), with variants associated with adult BMI acting as early as 4 to 6 years old. However, we demonstrated a completely distinct genetic makeup for peak BMI during infancy, influenced by variation at the LEPR/LEPROT locus. These findings suggest that different genetic factors control infant and child BMI. In light of the obesity epidemic, these findings are important to inform the timing and targets of prevention strategies.

Genetic insights into fetal growth and measures of glycaemic regulation and adiposity in adulthood: a family-based study

Background

The genetics of fetal insulin release and/or action have been suggested to affect fetal growth, adult insulin resistance and adult body composition. The genetic correlation between body composition at birth versus glycaemic regulation and body composition in adulthood have, however, not been well studied. We therefore aimed to investigate these genetic correlations in a family-based cohort.

Methods

A Danish family cohort of 434 individuals underwent an oral glucose tolerance test with subsequent calculation of surrogate measures of serum insulin response and insulin sensitivity. Measures of fetal growth were retrieved from midwife journals. Heritability and genetic correlations were estimated using a variance component model.

Results

A high heritability of 0.80 was found for birth weight, whereas ponderal index had a heritability of 0.46. Adult insulin sensitivity measured as Matsuda index was genetically correlated with both birth weight and ponderal index (ρG = 0.36 (95% CI: 0.03; 0.69) and ρG = 0.52 (95% CI, 0.15; 0.89), respectively). Only birth weight showed a significant genetic correlation with adult weight (ρG = 0.38 (95% CI: 0.09; 0.67)) whereas only ponderal index was genetically inversely correlated with fasting insulin (ρG = - 0.47 (95% CI: - 0.86; - 0.08) and area under the curve for insulin release during the oral glucose tolerance test (ρG = - 0.66 (95% CI: - 1.13; - 0.19)).

Individual as well as combined adjustment for 45 selected birth weight, obesity and type 2 diabetes susceptibility gene variants did not affect the correlations.

Conclusions

The genetics of both birth weight and ponderal index appear to be under the same genetic influence as adult insulin resistance. Furthermore, ponderal index and adult insulin release seem to be partly shared, as well as the genetics of birth weight and adult weight.

Word count abstract: 281.

Electronic supplementary material

The online version of this article (10.1186/s12881-018-0718-2) contains supplementary material, which is available to authorized users.

Obesity and obesogenic growth are both highly heritable and modified by diet in a nonhuman primate model, the African green monkey (Chlorocebus aethiops sabaeus)

Objective:

In humans, the ontogeny of obesity throughout the life course and the genetics underlying it has been historically difficult to study. We compared, in a non-human primate model, the lifelong growth trajectories of obese and non-obese adults to assess the heritability of and map potential genomic regions implicated in growth and obesity.

Study population:

A total of 905 African green monkeys, or vervets (Chlorocebus aethiops sabaeus) (472 females, 433 males) from a pedigreed captive colony.

Methods:

We measured fasted body weight (BW), crown-to-rump length (CRL), body-mass index (BMI) and waist circumference (WC) from 2000 to 2015. We used a longitudinal clustering algorithm to detect obesogenic growth, and logistic growth curves implemented in nonlinear mixed effects models to estimate three growth parameters. We used maximum likelihood variance decomposition methods to estimate the genetic contributions to obesity-related traits and growth parameters, including a test for the effects of a calorie-restricted dietary intervention. We used multipoint linkage analysis to map implicated genomic regions.

Results:

All measurements were significantly influenced by sex, and with the exception of WC, also influenced by maternal and post-natal diet. Chronic obesity outcomes were significantly associated with a pattern of extended growth duration with slow growth rates for BW. After accounting for environmental influences, all measurements were found to have a significant genetic component to variability. Linkage analysis revealed several regions suggested to be linked to obesity-related traits that are also implicated in human obesity and metabolic disorders.

Conclusions:

As in humans, growth patterns in vervets have a significant impact on adult obesity and are largely under genetic control with some evidence for maternal and dietary programming. These results largely mirror findings from human research, but reflect shorter developmental periods, suggesting that the vervet offers a strong genetic model for elucidating the ontogeny of human obesity.

Frequency of fat mass and obesity-associated gene rs9939609 and peroxisome proliferator-activated receptor gamma 2 gene rs1801282 polymorphisms among Trinidadian neonates of different ethnicities and their relationship to anthropometry at birth

BACKGROUND

The fat mass and obesity-associated gene (FTO) rs9939609 and peroxisome proliferator-activated receptor gamma 2 gene (PPARG2) rs1801282 polymorphisms are type 2 diabetes mellitus susceptibility gene variants associated with obesity. This study examined whether these variants are associated with anthropometry at birth among a representative multi-ethnic sample of Trinidadian neonates.

METHODS

Cord blood was obtained from consecutive term live births and DNA was genotyped for FTO and PPARG2 variants using polymerase chain reaction. Associations between neonate anthropometry at birth and genotype frequency were assessed using the χ(2) test and linear regression.

RESULTS

Significant associations were observed between neonate ethnicity and PPARG2 (p = 0.005) and FTO (p = 0.017) variants: high-risk alleles were more prevalent among African than South Asian neonates for both variants. The allelic and genotypic frequencies for mixed neonates were between those for the African and those for the South Asian neonates. No significant relationship was observed between rs9939609 and rs1801282 and anthropometric measures. For both variants, the allelic and genotypic frequencies among the African and South Asian neonates mirrored those found elsewhere for similar ethnic groups.

CONCLUSIONS

Neonates of African ethnicity possess the highest frequency of rs9939609 and rs1801282 alleles and genotypes; this may be associated with ethnic differences in the risk of lifestyle diseases.

Body composition assessment in the infant

Body composition assessment provides a sharper picture of the human biological response to genetic and environmental influences than measures of body size and weight. Infant body composition is particularly important as a marker of fetal adaptation and developmental programming of subsequent health and disease, but until recently, the range of options for measuring infant body composition was relatively narrow. The purpose of this Toolkit: Methods in Human Biology review is to provide a comprehensive overview of methods of body composition methods currently used in infants 0 to 2 years of age, including anthropometric prediction equations, air displacement plethysmography (ADP), dual energy X-ray absorptiometry (DXA), bioelectrical impedance analysis (BIA), isotope dilution, and magnetic resonance imaging (MRI). Information on the reliability, validity, and accuracy of the methods is provided. Unique aspects of infant physiology and behavior create challenges for body composition assessment, but this review provides guidance on suitable testing approaches and environments that may aid researchers in this important area of investigation.

Impact of annual body mass index gain on obesity development in Japanese 6-year-old non-obese children

BACKGROUND

Effective timing of preventive intervention for adolescent obesity in non-obese school-aged children remains unclear. The aim of this study was to examine the impact of annual body mass index (BMI) gain on the development of adolescent obesity in 6-year-old non-obese Japanese children.

METHODS

Longitudinal weight and height data were collected annually from 9723 children aged 6-14 years, and individual per-year BMI gains were calculated. The BMI ≥ the 95th percentile for each age and sex defined obesity. In 6-year-old non-obese children, logistic regression analyses were applied to correlate the annual BMI gain at each age with obesity at a final survey.

RESULTS

The 6-year-old non-obese children who became obese at a final survey showed larger annual BMI gains at any age compared with their peers with respect to baseline BMI. Increases in annual BMI gain, even in early school age, raised the risk of adolescent obesity. Categorical analysis also showed that children aged 6-7 years with higher annual BMI gains than 1-SD above the mean had a significant risk for adolescent obesity (OR: 4.39 [95%CI: 2.98-6.46] in boys and 3.83 [95%CI: 2.60-5.63] in girls, respectively).

CONCLUSIONS

A larger annual BMI gain at any school age is a risk for adolescent obesity in 6-year-old non-obese children with no critical period. This suggests the need for earlier and continuous school-based surveillance using annual BMI gain for preventive intervention of adolescent obesity development.

Characterization of the infant BMI peak: sex differences, birth year cohort effects, association with concurrent adiposity, and heritability

OBJECTIVES

To characterize an early trait in the BMI-for-age curve, the infant BMI peak.

METHODS

BMI-for-age curves were produced for 747 non-Hispanic, white Fels Longitudinal Study participants, from which individual age (AgePeak ) and BMI (BMIPeak ) at maximum infant BMI were estimated. Multivariable general linear regression was used to examine the effects of sex and birth year cohort (1929-1950, 1951-1970, and 1971-2010) on AgePeak and BMIPeak , with associations between BMIPeak and concurrent sum of four skinfold thicknesses assessed in a subsample (N = 155). Heritability (h(2) ) of AgePeak and BMIPeak was estimated using maximum-likelihood variance components analysis.

RESULTS

AgePeak occurred at 9 months of age in both sexes, but BMIPeak was 0.4 kg/m(2) higher for boys than for girls (P-value < 0.001). Infants born between 1971 and 2010 experienced a 1.5 month earlier AgePeak and a 0.35 kg/m(2) lower BMIPeak than infants born between 1929 and 1950 (P-values < 0.001). Skinfold thickness explained 37% of the variance in BMIPeak in boys and 20% of the variance in girls (p-values < 0.001). AgePeak and BMIPeak were significantly heritable (h(2) = 0.54 and 0.75, respectively).

CONCLUSIONS

Both AgePeak and BMIPeak decreased over successive birth year cohorts in the Fels Longitudinal Study. Despite a positive association of BMIPeak with concurrent adiposity, AgePeak appears to occur later than does the well-documented peak in infant fat mass and BMIPeak does not capture known sex differences in infant adiposity. Strong heritability of these infant BMI traits suggests investigation of genetic control, and validation of their relationship to body composition is greatly needed.