Bivariate linkage confirms genetic contribution to fetal origins of childhood growth and cardiovascular disease risk in Hispanic children

Adolescent obesity in the past decade: A systematic review of genetics and determinants of food choice

Background and purpose:

As the incidence of global obesity increases, concerns about adverse health outcomes in adolescents continues to rise. The complexity and expense of this problem require early recognition and specific preventive treatments. Knowledge of genetics and determinants of food choices contributing to adolescent obesity warrants further examination. The primary goal was to appraise the literature from the past decade (2007–2017) on the current state of food choice and genetic determinants of adolescent overweight/obesity in the United States. The secondary goal was to determine trends in the literature and areas for future research.

Methods:

A systematic review of research studies in the United States from 2007 to 2017 was completed. Database searches were conducted using CINAHL, Embase, PsycINFO, PsycArticles, PubMed, Scopus, Academic Search Complete, Web of Science, BIOSIS, and the Cochrane Library. A total of 535 studies were selected. Of these, 283 studies focused on determinants of food choices and 165 studies focused on genetic factors.

Conclusions:

A total of 41 full-text articles included in this literature review contained studies limited exclusively to adolescents. Stress factors related to food choices demonstrated a new trend being explored. The need for precision health, the application of genetic information, could uncover ways food choices affect adolescent obesity.

Implications for practice:

The etiology of adolescent obesity requires that nurses gain knowledge of genetics and food choice determinants to inform personalized treatments for adolescents, which may establish effective interventions that promote healthy weight achievement.

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.

Sex-specific genetic influence on thyroid-stimulating hormone and free thyroxine levels, and interactions between measurements: KNHANES 2013-2015

BACKGROUND

Although a wide range of genetic influences on thyroid-stimulating hormone (TSH) and free thyroxine (fT4) levels have been reported, sex differences in the genetic influences have not been well described.

METHODS

We assessed TSH and fT4 levels in 2,250 subjects without thyroid peroxidase antibody, with data obtained from the Korea National Health and Nutrition Examination Surveys (KNHANES) conducted from 2013 to 2015. Using variance decomposition methods, the variation of TSH and fT4 levels was divided into genetic and environmental components common to both sexes, and to males and females separately. The genetic correlation between TSH and fT4 levels was also assessed in both sexes, and in males and females separately.

RESULTS

Narrow-sense heritability for TSH and fT4 were 54% and 56%, respectively. Sex-specific heritability for TSH levels was significantly higher in females than in males (75% and 41%, respectively; p = 0.037). Heritability for fT4 levels was not significantly different between males and females (62% and 52%, respectively; p = 0.335). TSH and fT4 levels showed a negative genetic correlation in females (ρg = -0.347, p = 0.040) after regressing out the influences of environmental covariates, but this correlation was not present in males (ρg = -0.160, p = 0.391).

CONCLUSIONS

The genetic influences on individual TSH levels were more prominent in females than in males. In addition, female-specific pleiotropy between TSH and fT4 might be a clue that this stronger genetic influences in females would mainly affect thyroid function per se, rather than other TSH-related factors that do not primarily trigger the negative feedback loop between TSH and fT4.

Indicators of fetal growth and adult liver enzymes: the Bogalusa Heart Study and the Cardiovascular Risk in Young Finns Study

Despite the interest in the relationship of fetal exposures to adult cardiovascular disease, few studies have examined indicators of adult fatty liver disease as an outcome. Previous results are inconsistent, and indicate possible variation by sex. Adult liver enzymes [γ-glutamyl transferase (GGT), alanine transaminase (ALT) and aspartase transaminase (AST)] were measured in two cohort studies: the Bogalusa Heart Study (BHS; n=1803) and the Cardiovascular Risk in Young Finns (YF; n=3571) study, which also had ultrasound measures of liver fat (n=2546). Predictors of dichotomized (clinical cut-offs) and continuous (within the reference range) liver enzymes included low birthweight (4000 g), small-for-gestational-age (birthweight 90th percentile), and preterm birth. Multiple logistic and linear regression were conducted, adjusted for medical, behavioral and socioeconomic indicators. Interactions with sex were also examined. In BHS, birth measures were not strongly associated with clinically high levels of liver enzymes, and within the reference range measures of reduced growth were associated with increased AST in women. In the YF study, at least one marker of reduced growth was associated with higher GGT, higher ALT and higher AST (in women). Probable fatty liver on ultrasound was associated with low birthweight (2.41, 1.42-4.09) and preterm birth (2.84, 1.70-4.76). These results suggest a link between birth parameters and adult fatty liver, but encourage consideration of population variation in these relationships.

Clinical characteristics, treatment patterns and outcomes of Hispanic hypertensive patients

Hispanics are the largest and fastest-growing minority population in the United States, currently comprising about 16.3% (52 million) of the total population. With an increased prevalence of metabolic risk factors in this population, the rate of uncontrolled hypertension (HTN) in Hispanics significantly exceeds the rates observed among non-Hispanic blacks and whites. Unfortunately, data on HTN in Hispanics remains limited due to the under-representation of Hispanics in clinical trials; with most of the data primarily restricted to observational and retrospective subgroup analyses. This article aims to review the available data on prevalence, awareness and control of HTN, risk factors and some of the challenges unique to the Hispanics population. We also discuss treatment strategies derived from large HTN trials that included Hispanics.

Hypertension and antihypertensive therapy in Hispanics and Mexican Americans living in the United States

Hypertension is a major independent risk factor for cardiovascular diseases, which are the most frequent cause of death worldwide. In addition, the risk of hypertension has been associated with racial and/or ethnic background. Hispanics are the largest and fastest-growing minority population in the United States, currently comprising about 16.3% (50.5 million) of the total population; these numbers will continue to increase into the next 10 years. The rate of uncontrolled hypertension in Hispanics significantly exceeds the rates observed among non-Hispanic blacks and whites. The reasons for these racial and ethnic differences in blood pressure control may include factors such as lack of access to health care, low socioeconomic status, language barriers, degree of acculturation, poor doctor-patient communication, and genetic factors. This article provides an up-to-date summary of epidemiological and treatment aspects of high blood pressure in the US Hispanic population. Because Mexican Americans constitute approximately 66% of US Hispanics, data sources that focus on Mexican Americans are also discussed.

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

While the associations of common variants in the FTO gene with obesity have been widely replicated in adults, there is conflicting evidence regarding their effects in infancy. We hypothesize that the genetic influences on growth traits vary during infancy, and that conflicting results may stem from variation in the ages at which FTO associations have been examined. Using longitudinal weight and length data at 0, 1, 3, 6, 9, 12, 18, 24, 30, and 36 months in 917 (444 females, 473 males) family members from the Fels Longitudinal Study, we used a variance components-based approach (SOLAR) to: (i) examine differences in heritability (gene-by-age interaction) in weight, length, relative weight (BMI and ponderal index (PI)) and instantaneous weight and length velocities over the course of infancy, and (ii) test whether a common FTO variant (rs9939609) was associated with infant growth at three ages (maximum trait heritability, birth and 36 months). All heritabilities at birth (of 39-74%) were significant (P < 3.9 × 10(-10)), but changed with age (gene-by-age interaction, P < 0.05). Weight, relative weight, and weight velocity reached maximum heritabilities (of 76-89%) at 6-9 months, while length and length velocity reached maximum heritabilities (of 96-99%) at 18-30 months. We found no association of rs9939609 with growth status or velocity measured at any age (P > 0.11). This study for the first time demonstrates the fluctuation of genetic influences on infant growth, but further work is required to determine which gene variants explain the strong additive genetic effects observed.

Nature and nurture in infant appetite: analysis of the Gemini twin birth cohort

BACKGROUND

A strong genetic influence on appetitive traits has been shown in children and adults, but no studies have examined appetite in early infancy, even though avidity of appetite has been linked with a higher risk of obesity.

OBJECTIVE

The objective was to investigate the heritability in early infancy of 4 appetitive traits that have been shown to be heritable later in childhood.

DESIGN

Data are from the Gemini Study, a population-based sample of twins (n = 2402 pairs) born in England and Wales in 2007. To describe their children's eating behavior during the first 3 mo of life while they were still exclusively milk fed, the parents of the twins completed 4 subscales of the Baby Eating Behavior Questionnaire: "enjoyment of food," "food responsiveness," "slowness in eating," and "satiety responsiveness." Heritability was estimated by using quantitative genetic model fitting.

RESULTS

Heritability was high for slowness in eating (84%; 95% CI: 83%, 86%) and satiety responsiveness (72%; 95% CI: 65%, 80%) and moderate for food responsiveness (59%; 95% CI: 52%, 65%) and enjoyment of food (53%; 95% CI: 43%, 63%).

CONCLUSIONS

Genetically determined variability in appetitive traits may be one of the pathways through which genes influence the growth rate in infancy. Early identification of infants with avid appetites may make it possible to implement strategies to attenuate the expression of these traits before excessive weight gain occurs.

Racial/ethnic disparities in obstetric outcomes and care: prevalence and determinants

Wide disparities in obstetric outcomes exist between women of different race/ethnicities. The prevalence of preterm birth, fetal growth restriction, fetal demise, maternal mortality, and inadequate receipt of prenatal care all vary by maternal race/ethnicity. These disparities have their roots in maternal health behaviors, genetics, the physical and social environments, and access to and quality of health care. Elimination of the health inequities because of sociocultural differences or access to or quality of health care will require a multidisciplinary approach. We aim to describe these obstetric disparities, with an eye toward potential etiologies, thereby improving our ability to target appropriate solutions.

Risks and management of obesity in pregnancy: current controversies

PURPOSE OF REVIEW

To explore recent developments in obesity-related topics of interest and importance to obstetricians. Specifically addressed are the impact of gestational weight gain on perinatal risk, the increased risk of congenital anomalies in offspring, developmental origins of health and disease in offspring, and reproductive issues following bariatric surgery.

RECENT FINDINGS

Limiting maternal weight gain in obese women to less than 15 lb may favorably attenuate perinatal risk (macrosomia, cesarean delivery, preeclampsia) but increase risk for small-for-gestational-age newborns. Obese women are at significantly increased risk for offspring to develop open neural tube defects and congenital heart disease as well as other anomalies. Impaired sonographic visualization in this population may impede prenatal diagnosis of these serious birth defects. Intrauterine nutritional overabundance may cue adaptive fetal responses predisposing to childhood and adult obesity as well as the metabolic syndrome. Bariatric surgery, the only effective treatment for morbid obesity, causes lifelong physiologic and anatomic changes associated with significant reproductive implications. Procedures can predispose to caloric and micronutrient deficiencies, improved fertility and fecundity, and late surgical complications. Pregnancy outcomes are typically similar to those of women without previous bariatric surgery and better than those of untreated morbidly obese women.

SUMMARY

Obesity and its surgical treatment are associated with lifelong health implications for the mother as well as her offspring. An appreciation of these obesity-related reproductive issues is critical for optimal care of this growing segment of the female population.

Childhood obesity: are genetic differences involved?

This brief review focuses on the genetic contribution to childhood obesity. Evidence for a genetic component to excess body weight during growth is presented from the perspective of genetic epidemiology studies. Parental obesity is a predictor of childhood excess weight. The familial risk ratio for childhood obesity when a parent is obese reaches >2.5. Birth weight is characterized by a genetic heritability component on the order of 30%, with significant maternal and paternal effects in addition to the newborn genes. About 5% of childhood obesity cases are caused by a defect that impairs function in a gene, and >/=5 of these genes have been uncovered. However, the common forms of childhood obesity seem to result from a predisposition that primarily favors obesogenic behaviors in an obesogenic environment. Candidate gene and genomewide association studies reveal that these obesogenic genes have small effect sizes but that the risk alleles for obesity are quite common in populations. The latter may translate into a highly significant population-attributable risk of obesity. Gene-environment interaction studies suggest that the effects of predisposing genes can be enhanced or diminished by exposure to relevant behaviors. It is possible that the prevalence of childhood obesity is increasing across generations as a result of positive assortative mating with obese husbands and wives contributing more obese offspring than normal-weight parents.

Why are some people left-handed? An evolutionary perspective

Since prehistoric times, left-handed individuals have been ubiquitous in human populations, exhibiting geographical frequency variations. Evolutionary explanations have been proposed for the persistence of the handedness polymorphism. Left-handedness could be favoured by negative frequency-dependent selection. Data have suggested that left-handedness, as the rare hand preference, could represent an important strategic advantage in fighting interactions. However, the fact that left-handedness occurs at a low frequency indicates that some evolutionary costs could be associated with left-handedness. Overall, the evolutionary dynamics of this polymorphism are not fully understood. Here, we review the abundant literature available regarding the possible mechanisms and consequences of left-handedness. We point out that hand preference is heritable, and report how hand preference is influenced by genetic, hormonal, developmental and cultural factors. We review the available information on potential fitness costs and benefits acting as selective forces on the proportion of left-handers. Thus, evolutionary perspectives on the persistence of this polymorphism in humans are gathered for the first time, highlighting the necessity for an assessment of fitness differences between right- and left-handers.

Impact of infant feeding practices on childhood obesity

Childhood obesity is a complex disease influenced by genetic and environmental factors and their interactions. The current surge in childhood obesity in the United States is attributable to an interaction between a genetic predisposition toward obesity and a permissive environment. Several recent systematic reviews and meta-analyses have been published on the association between breast-feeding and childhood obesity. In these analyses, adjustment for confounding factors attenuated or nullified the protective effect of breast-feeding on later obesity. The Viva La Familia Study was designed to identify genetic and environmental factors affecting obesity and its comorbidities in 1030 Hispanic children from 319 families. Odds ratios for potential risk factors associated with childhood overweight were computed using binary logistic regression for panel data. Early infant-feeding practices were not significant. Salient independent risk factors for childhood obesity in this cohort of Hispanic children were age, birth weight, maternal obesity, paternal obesity, number of children in the family, and the percentage of awake time spent in sedentary activity. Breast-feeding may have a small protective effect against childhood obesity, although residual confounding may exist. Human milk is exquisitely fitted for optimal infant growth and development and may uniquely modulate neuroendocrine and immunologic pathways involved in the regulation of body weight. Nevertheless, other genetic and environmental determinants such as socioeconomic status, parental obesity, smoking, birth weight, and rapid infancy weight gain far supersede infant-feeding practices as risk factors for childhood obesity.