The genetic and environmental sources of body mass index variability: the Muscatine Ponderosity Family Study.

The role of genetic and environmental factors in determining the variability in body mass index (BMI; kg/m2) was investigated in 1,302 relatives identified through 284 schoolchildren from Muscatine, IA. BMI levels were first adjusted for variability in age, by gender and by relative type. There was significant familial aggregation of adjusted BMI in the pedigrees, as indicated by inter- and intraclass correlation coefficients significantly different from zero. A mixture of two normal distributions fit the adjusted BMI data better than did a single normal distribution. Genetic and environmental models that could explain both the familial aggregation and the mixture of normal distributions were investigated using complex segregation analysis. There was strong support for a single recessive locus with a major effect that accounted for almost 35% of the adjusted variation in BMI. Polygenic loci accounted for an additional 42% of the variation. Approximately 23% of the adjusted variation was not explained by genetic factors. For spouses living in the same household, their shared environment accounted for 12% of their variation. For siblings living in the same household, their shared environment accounted for 10% of their variation. While shared environments contributed to variation in adjusted BMI, more than 75% of the variation was explained by genetic factors that include a single recessive locus. Approximately 6% of the individuals in the population from which these pedigrees were sampled are predicted to have two copies of the recessive gene, while 37% of the individuals are predicted to have one copy of the gene.     

Cognitive abilities, androgen levels, and body mass index in 5-year-old children

This study explores the potential relationship between a series of cognitive abilities and testosterone, dehydroepiandrosterone (DHEA), androstenedione, and body mass index (BMI) measurements in 5-year-old children. 60 boys and 69 girls were administered a test (K-BIT) which provided measurements of fluid intelligence (Matrices subtest), crystallized intelligence (Vocabulary subtest), and IQ composite (the combination of the two subtests); a sub-sample of 48 boys and 61 girls was also subjected to diverse tests related to theory of mind (affective labeling, appearance-reality distinction, display rules, and false belief). Testosterone, DHEA, and androstenedione levels were measured using an enzyme immunoassay technique in saliva samples. An analysis of variance failed to reveal any significant differences between boys and girls in any of the cognitive abilities assessed. The correlation analysis revealed a positive relationship between fluid intelligence and testosterone levels in boys, a negative relationship between crystallized intelligence and androstenedione levels in girls, and between affective labeling and androstenedione levels in boys. A multiple regression analysis indicated that androstenedione and BMI were the best predictors for some of the cognitive abilities assessed.     

Long-term trends in body mass index of children in Jena, Eastern Germany

The body mass index (BMI) is widely used as an indicator of nutritional status of individuals and groups, changes in this measure reflecting changes in living conditions. The purpose of this paper is to present long-term BMI trends of schoolchildren from Jena/Eastern Germany over 125 years. The analysis is based on 10 anthropological investigations carried out between 1880 and 2005/2006 and belongs to the longest running, continuous investigation of schoolchildren in a single community worldwide. The average BMI of the 7- to 14-year-old probands generally increases between the first investigation in 1880 and the last study in 2005/2006 by 1.8 kg/m(2) in boys and by 2.1 kg/m(2) in girls. However, this long-term increase of the BMI does not occur continuously. The trend was interrupted for example by declining average BMI values between 1932 and 1944. In contrast, the time after German reunification is characterised by a marked increase in this measure. The changes in BMI of Jena schoolchildren are also analysed in relation to energy intake in different years. There is an association between changes in energy intake and changes in BMI, which weakens after 1985. This indicates that the recent dramatic increase in the prevalence of overweight and obesity is not only due to an increased energy intake but also reflects a more inactive lifestyle of children and adolescents. The continuing change in the BMI pattern of Jena children and adolescents is discussed in regard to programmes of prevention of overweight and obesity.     

A statistical human rib cage geometry model accounting for variations by age,sex, stature and body mass index

In this study, we developed a statistical rib cage geometry model accounting for variations by age, sex, stature and body mass index (BMI). Thorax CT scans were obtained from 89 subjects approximately evenly distributed among 8 age groups and both sexes. Threshold-based CT image segmentation was performed to extract the rib geometries, and a total of 464 landmarks on the left side of each subject?s ribcage were collected to describe the size and shape of the rib cage as well as the cross-sectional geometry of each rib. Principal component analysis and multivariate regression analysis were conducted to predict rib cage geometry as a function of age, sex, stature, and BMI, all of which showed strong effects on rib cage geometry. Except for BMI, all parameters also showed significant effects on rib cross-sectional area using a linear mixed model. This statistical rib cage geometry model can serve as a geometric basis for developing a parametric human thorax finite element model for quantifying effects from different human attributes on thoracic injury risks.     

Secular changes in height, body weight, body mass index and pubertal development in male children and adolescents in Krakow, Poland

This study examined the secular changes in height, body weight, body mass index and pubertal development in male children and adolescents in Krakow (Poland) over the past 80 years, with an emphasis on the last decade (2000-2010). The survey of the population of Krakow is a continuation of observations conducted in that area for many years. The analysis aims to determine whether in the last decade Krakow still witnessed the secular trend, and what form the trend took. The body height and weight, and body mass index (BMI), of 1862 boys aged 3.5-18.5 years were analysed, against the background of a survey series from the years 1938 (N = 1801), 1971 (N = 2045), 1983 (N = 3124) and 2000 (N = 2328). The mean body height, in almost all age categories, was greater than in the past; however the final height over the last decade remained the same. The mean values of body weight and BMI increased, especially in the last decade. Also, an acceleration of puberty in boys was observed. The last 10 years saw an over 3-month decrease in the age of initial appearance of pubic hair in boys. In conclusion, the last decade saw cessation of the growing taller trend: maximum body height stabilized at approximately 179 cm, but weight and BMI increased. Also, a distinct acceleration of puberty was noticed. Lack of height increase, at the same time as weight gain and puberty acceleration, indicate a progressing developmental disharmony.     

On the relation between genetic and environmental variability in animals

Summary If a phenotypic character is under stabilizing selection, the selective disadvantage of a nonoptimal genotype will decrease exponentially to zero as the proportion of phenotypic variation that is environmental in origin -V _e /V _p - increases. Under the modified mutation-drift hypothesis of genetic polymorphism, the proportion of mutations that are effectively neutral and average heterozygosity should increase with this ratio. Invertebrates, because of their small size, fast development, and low degree of homeostasis (relative to vertebrates), are expected to show a larger environmental component of phenotypic variation than vertebrates. This may help explain why invertebrates are in general more genetically variable than vertebrates and why, when laboratory populations ofDrosophila are maintained in heterogeneous environments, genetic variability is lost less rapidly than when they are kept in constant conditions.     

Validity of the body mass index and fat mass index as an indicator of obesity in children aged 3-5 year

The validity of the BMI and fat mass index (FMI) as indicators of obesity was evaluated in a group of 3-5 yr old (n=486) children. Bioelectrical impedance analysis (BIA) was measured (using 50 kHz and tetrapolar electrodes) in order to calculate percent fat mass (%FM) and FMI (fat mass/stature squared). For boys, obesity was defined as > or =20%FM. For girls, the cutoff for obesity was > or =25%FM. However, obesity was defined as a BMI at or above the 90th percentile of age- and sex-specific data in this study. The percentile cutoffs for FMI were the same as for BMI using the same sample. There were correlations between BMI or FMI and %FM, but there was no significant correlation between BMI or FMI and stature. Therefore, it appears that both the BMI and FMI in this study are far more useful indices with which to assess obesity, and are reasonable indicators of fatness. However, with the use of %FM by BIA as the criterion for obesity, BMI and FMI had high specificities (95.5-96.4% for BMI and 99.5-100% for FMI) and lower but variable sensitivities (30.4-37.5% for BMI and 42.9-68.8% for FMI). Thus, almost all children who were not obese were classified correctly. In contrast, many obese children were not correctly identified by BMI and FMI. Therefore, we conclude that BMI should be used with caution as an indicator of childhood obesity. The new recommendations based on the FMI approach for defining childhood obesity are associated with a level of sensitivity that is somewhat higher than that of the BMI approach. Caution should, however, be used in generalizing from the findings in this study, and a further investigation of the issue is required.     

Reference values for height, weight and body mass index of German born Turkish children

Turkish children and adolescents born in Northern Europe grow different from native Northern European children, but reference values for height, weight and BMI for these children do not exist. With this study, we intend to provide growth standards for German born Turkish children. Data were obtained from 797 Turkish children and adolescents born in Germany age 0-25.8 years (males), respectively 0-18.3 years (females). We generated synthetic reference values for height, weight, and BMI. The results show that Turkish children and adolescents are heavier after the age of 6 years, and that they remain short after puberty. Eighteen year old Turkish men, and 15-year-old Turkish women are shorter (males 175.2 cm vs. 180.4 cm, p < 0.05; females 159.3 cm vs. 165.0 cm, p < 0.05), and heavier than Germans. Six out of 53 young Turkish men and 9 out of 100 young Turkish women were obese. Twelve out of 53 young Turkish men (23%) and 18 out of 100 young Turkish women (18%) have fallen below the 3rd centile for height. It can be concluded that growth of Turkish children and adolescents born in Germany significantly differs from native children. Reference LMS values for body height, weight and BMI of German born Turkish boys and girls are presented.     

Age at diagnosis, body mass index and physical morbidity in children and adults with the Prader-Willi syndrome

Age at diagnosis, Body Mass Index and physical morbidity in children and adults with the Prader-Willi syndrome: The medical findings of a population of 54 Prader-Willi patients with a molecular confirmed diagnosis are discussed. In the age group aged 18 or younger, a reasonably good control of weight as measured by Body Mass Index (BMI) is found. This is probably due to the fact that diagnosis was made at an early age and intensive diet management was started early. Despite their relatively low BMI, these children remain at high risk for developing scoliosis requiring active treatment (28% of the children). Adults (older than 18) diagnosed at the age of 10 or later have a high risk for developing obesity and obesity related health problems such as hypertension (38%), non-insulin dependant diabetes mellitus (11%) and cardio respiratory failure (16%).     

Overweight in urban schoolchildren assessed by body mass index and body fat mass in Dalian, China

In order to assess overweight in urban schoolchildren (298 boys and 298 girls) aged 9-16 years in Dalian, China, their body height, weight, skinfolds at triceps, biceps, subscapular and suprailiac, and body circumferences of mid-upper arm, waist and hip were measured. The results showed that the prevalence of overweight, based on the United States Centers for Disease Control 2000 reference values using body mass index (BMI), was 22.9% in boys and 10.4% in girls, which was higher than that of indicated in Chinese national surveys of recent decades. More boys were overweight than girls due to excessive increase in body fat, although the prevalence of overweight in girls prevalence increased from 13 years. Discussion here focuses on the effects of behavioral patterns on overweight in Dalian schoolchildren, paying attention to gender difference.     

Income and body mass index in Europe

The problem of obesity is alarming public health authorities around the world. Therefore, it is important to study its determinants. In this paper, we explore the empirical relationship between household income and body mass index (BMI) in nine European Union countries. Our findings suggest that, in general, the association is negative for women and nonexistent for men. Moreover, once we decompose household income into “own labor earnings” and “other household income”, we find that the different relationship for men and women appears to be driven by the negative relationship between BMI and “own labor earnings” for women.     

The estimation of body mass index and physical attractiveness is dependent on the observer's own body mass index

A disturbance in the evaluation of personal body mass and shape is a key feature of both anorexia and bulimia nervosa. However, it is uncertain whether overestimation is a causal factor in the development of these eating disorders or is merely a secondary effect of having a low body mass. Moreover, does this overestimation extend to the perception of other people''s bodies? Since body mass is an important factor in the perception of physical attractiveness, we wanted to determine whether this putative overestimation of self body mass extended to include the perceived attractiveness of others. We asked 204 female observers (31 anorexic, 30 bulimic and 143 control) to estimate the body mass and rate the attractiveness of a set of 25 photographic images showing people of varying body mass index (BMI). BMI is a measure of weight scaled for height (kg m(- 2)). The observers also estimated their own BMI. Anorexic and bulimic observers systematically overestimated the body mass of both their own and other people''s bodies, relative to controls, and they rated a significantly lower body mass to be optimally attractive. When the degree of overestimation is plotted against the BMI of the observer there is a strong correlation. Taken across all our observers, as the BMI of the observer declines, the overestimation of body mass increases. One possible explanation for this result is that the overestimation is a secondary effect caused by weight loss. Moreover, if the degree of body mass overestimation is taken into account, then there are no significant differences in the perceptions of attractiveness between anorexic and bulimic observers and control observers. Our results suggest a significant perceptual overestimation of BMI that is based on the observer''s own BMI and not correlated with cognitive factors, and suggests that this overestimation in eating-disordered patients must be addressed directly in treatment regimes.     

Trends in body mass index, prevalence of overweight and obesity in preschool Lithuanian children, 1986-2006

The study provides the body mass index (BMI), the prevalence of overweight and obesity in preschool Lithuanian children, 1986-2006. In the 2003-2006 more than 1000 preschool 3-6 year old children from Vilnius (the capital of Lithuania) were investigated according to the standard anthropometric methods. The prevalence of overweight (OW) and obesity (OB) was estimated according to the cut-off points recommended by the International Obesity Task Force (IOTF). Recent data were compared with the data of preschool children from the 1986 Vilnius study and with the data from the other countries. The BMI of preschool children did not change significantly during the last 20 years, except for the statistically significant BMI increment in 6 years old girls. The prevalence of OB among preschool Lithuanian children was low (0.8%-3.7% in boys, and 0-1.9% in girls) and did not change significantly during 1986-2006. The prevalence of OW was higher in preschool girls (10.7%-18.2%) in comparison with preschool boys (6.5%-12.4%). The significant increment of the prevalence of OW was observed among the 6-year-old girls from the 2006 study in comparison with the 1986 study. The possible socio-economic reasons of the defined trend in the BMI and prevalence of OW and OB among preschool Lithuanian children are discussed in the paper.     

Founder effects and genetic variability in Quebec

Knowledge of the genetic population structure lies at the heart of mapping studies aiming genes responsible for Mendelian and complex traits. The Quebec population, which is of mostly French descent, is considered an excellent model for such genetic epidemiological endeavours because it is a young founder population. Yet, the assessment of the founder effect has relied mostly on the observed distribution of monogenic diseases and on the analysis of the underlying mutations with investigations focusing on the Saguenay region. To eliminate this clinical bias and to obtain a more complete image of the genetic diversity, different regional populations of Quebec were investigated by analysing neutral markers that represent maternal, paternal and X chromosome lineages. Results indicate that Quebec does not appear more homogeneous nor significantly different from European populations. However, a series of regional founder effects, particularly visible at the level of rare variants, are observed. These effects can be explained by the successive migrations of descendants of the first immigrants from the initial sites of settlement towards the outer regions. Depending on the number of founders and their diversity, as well as on the degree of isolation and the magnitude of the interbreeding with the neighbouring or local populations, such as Amerindians or later migrants, the consequences of these regional founder effects are more or less detectable in the contemporary population.     

Age and sex variation of body mass index and waist circumference among the Santal children of Jharkhand, India

Central body fat (CBF) as measured by waist circumference (WC) etc. has now been considered as risk factor for chronic disease, disability, and death. It has been assumed that one's characteristic level of body fat, as measured by body mass index (BMI), and CBF unfolds during the normal course of growth and development. However, studies of the development of CBF show relatively weak consistency in comparison to body fat. But to the best of our knowledge, no study in this aspect has been undertaken on any Indian population to study the effect of age and sex on body fat and CBF during development. In view of the above consideration, the present work has been undertaken among 179 Santal (a tribal population) children (Boys = 107, Girls = 72) of the Galudih area in East Singbhum, Jharkhand, India. Anthropometric measurements of height, weight, and circumference of waist were taken from each subject using standard procedure. The mean ages of boys and girls were 10.94 years and 9.48 years, respectively. The mean BMI for boys and girls were 14.48 kg/m2 and 13.78 kg/m2 Percent of variance explained by age was much greater for BMI (> 50%) as compared to WC (7-10%) in both sexes. Two way ANOVA showed that BMI had a significant (p < 0.05) effect of age and not of sex, whereas age-sex interaction had a significant impact on WC. The results of the present cross-sectional study indicated that during growth and development unfolding of CBF and BMI is independent of one another. Different set(s) of gene(s), onset of growth hormones during the normal development or their interaction could have been considered for this differentiation.     

Changes of the body mass index during childhood

This article is devoted to the age changes of the Body Mass Index in Czech and Slovak children from 1.5 to 15 years of age. The anthropological survey was carried out in 1976-1978 in the whole region of the former Czechoslovakia. At the beginning of the research period children with normal weight predominate. After the seventh year of age there is a change and the BMI is increasing. As late as pre-puberty and puberty there is a change in a fractional part of the population, as children with overweight are increasing, more frequently in girls than in boys. However, its presence is not fundamentally increasing up to 15 years. The frequency differences in the different BMI categories between both sexes in the Czech and Slovak populations are only rarely statistically significant.