Genetics of human body size and shape: pleiotropic and independent genetic determinants of adiposity

Quantitative genetics of circulating Hyaluronic Acid (HA) and its correlation with hand osteoarthritis and obesity-related phenotypes in a community-based sample

BACKGROUND

One of the potential molecular biomarkers of osteoarthritis (OA) is hyaluronic acid (HA). HA levels may be related to the severity and progression of OA. However, little is known about the contribution of major risk factors for osteoarthritis, e.g. obesity-related phenotypes and genetics to HA variation.

AIM

To clarify the quantitative effect of these factors on HA.

SUBJECTS AND METHODS

An ethnically homogeneous sample of 911 apparently healthy European-derived individuals, assessed for radiographic hand osteoarthritis (RHOA), HA, leptin, adiponectin, and several anthropometrical measures of obesity-related phenotypes was studied. Model-based quantitative genetic analysis was used to reveal genetic and shared environmental factors affecting the variation of the study's phenotypes.

RESULTS

The HA levels significantly correlated with the age, RHOA, adiponectin, obesity-related phenotypes, and the waist-to-hip ratio. The putative genetic effects contributed significantly to the variation of HA (66.2 ± 9.3%) and they were also significant factors in the variations of all the other studied phenotypes, with the heritability estimate ranging between 0.122 ± 4.4% (WHR) and 45.7 ± 2.2% (joint space narrowing).

CONCLUSIONS

This is the first study to report heritability estimates of HA variation and its correlation with obesity-related phenotypes, ADP and RHOA. However, the nature of genetic effects on HA and its correlation with other study phenotypes require further clarification.

Longitudinal study of variation in body mass index in middle-aged UK females

The importance of changing patterns of obesity in society and its implications for public health are well recognized. However, the adult life course of body mass index (BMI) changes in individuals over time is largely unknown and has mostly been extrapolated from cross-sectional studies. The present study examines individual specific variation of BMI during a 15-year follow-up period in a community-based sample of UK females. We attempted to establish whether there is a common, generalized pattern which captures variation in BMI over time. The participants of this study belong to a prospective population cohort of British women studied intensively since 1989: the Chingford Study. The sample originally consisted of 1,003 women aged 45-68 years, who were assessed annually for BMI during follow-up period. Polynomial regression models were used to assess longitudinal BMI variation. We observed a great stability in individual BMI variation during the follow-up period, reflected by high correlations between the baseline BMI and follow-up BMI 10 and 15 years later (r = 0.876, N = 810, and r = 0.824, N = 638, respectively). We also found that three different major age-related patterns in BMI could be clearly identified: no change in 30.6% in 58% it increased and in 11.4% it decreased with age. Thus, our data suggest that individual age-related changes in BMI are very different. Therefore, simply combining all individuals into groups by any other criteria (age, sex, etc.) and overlooking the distinctive patterns of BMI change may lead to biased inferences in epidemiologic and etiologic research of the future.

Significant association between body composition phenotypes and the osteocalcin genomic region in normative human population

Osteocalcin, a major inorganic component of bone matrix and marker of bone formation, is also involved in regulation of glucose and fat mass metabolism. However, much uncertainty remains about whether the above effect on fat mass has a genetic component. Our main aim was to test whether a variation of body composition phenotypes is associated with BGLAP genomic region variants. To achieve this aim, we used an ethnically homogeneous discovery sample of 230 families consisting of 1112 apparently healthy individuals (561 males and 551 females) of European origin. We conducted association analysis between six SNPs and five obesity-related phenotypes: plasma levels of leptin, anthropometrical fat mass (FM), principal component scores of eight skinfold (SK_PC) and nine circumference (CR_PC) measurements, and body mass index (BMI). Two powerful and robust tools were applied: the pedigree disequilibrium test and variance component models, taking into account both familial and genetic effects. Significant association results were observed for all phenotypes. The most significant results were observed between the haplotype composed of three SNPs (rs2758605-rs1543294-rs2241106) and BMI (p=8.07(-7)), and CR_PC (p=5.29(-5)). The association with BMI was tested and confirmed in our replication study, including 2244 unrelated adult US Caucasians, who were previously assessed for whole genome SNP data. In addition, we obtained an evidence of potential non-additive interactions between the above three SNPs concerning their association with BMI. Bioinformatics sources suggest that the aforementioned interaction could originate from different genetic loci in this region; however, ascertaining the exact circumstances requires a detailed molecular-genetic study.

Association of FTO gene variants with body composition in UK twins

The association of FTO gene variants with body mass index (BMI) and other obesity characteristics is well established. However, uncertainties remain whether the association is present only in young populations and whether it is attributable to body fat mass specifically. We aimed to clarify these two questions in a large sample (N= 4,523 individuals) of middle-aged and older (range 40–80 years) British female twins. The women were assessed for BMI, waist and hip circumference, total lean (LBM) and fat (FBM) body mass. Since the majority of FTO association signals have been reported in a haploblock bordering 52,355–52,408 kb (on chromosome 16q12.2), we examined five genotyped and 43 imputed SNPs mapped to this block. Canonical correlation and other association analyses showed significant and consistent association between the selected SNP and studied body composition phenotypes, with p-values reaching p= 0.000004. Of particular interest, in addition to the expected significant associations between FTO variants and FBM, we also identified significant associations with LBM. These results suggest that the association between FTO variants and body composition phenotypes is present across a wide range of ages, and that FTO appears primarily to affect the amount of body soft tissue, influencing both fat and lean mass.

Mode of inheritance of finger dermatoglyphic traits among Vaidyas of West Bengal, India

BACKGROUND

It is well established that dermatoglyphics are genetically determined. But, to date, few studies have given attention to the inheritance pattern of dermatoglyphics. Furthermore, despite the existence of different advanced statistical packages, none of these previous studies implemented a model-fitting technique to reveal the mode of inheritance. Thus, the genetic nature of dermatoglyphics is still not clear.

AIM

In the present communication, an attempt has been made to provide some information regarding the genetics of finger dermatoglyphics by estimating the magnitude and mode of inheritance of these traits.

SUBJECTS AND METHODS

The fingerprints of 824 individuals from 200 families including two generations were collected from Barasat in North 24-Parganas, West Bengal. The study includes familial correlations between first-degree relatives and corresponding heritabilities. In the final stage, segregation analyses by the Pedigree Analysis Package (PAP) were conducted on these data to understand the mode of inheritance.

RESULTS

The major findings indicated the following: (a) Familial correlations in all possible relationships (except spouse correlation) were statistically significant and of comparable magnitude. (b) The corresponding heritabilities were in the range between 59% for Pattern Intensity Index (PII) and 77% for Total Finger Ridge Count (TFRC). These estimates were in agreement with previously published data on this subject. (c) By segregation analysis, the 'Sporadic', 'Environmental', 'No major gene effect' as well as 'No polygenic component' models were strongly rejected (p < 0.05) and the hypothesis of a major gene's (MG) influence on all studied traits was accepted, though the proportion of MG variance was low. (d) The Most Parsimonious Mendelian model clearly indicated the contribution of a major gene with dominant (for PII) and additive (for two ridge counts) effects.

CONCLUSION

The present report supports the evidence of the existence of a major gene on these dermatoglyphic traits and the transmission of this effect is consistent with Mendelian expectation.

Latent common genetic components of obesity traits

Background

Obesity is rapidly becoming a global epidemic. Unlike many complex human diseases, obesity is defined not just by a single trait or phenotype, but jointly by measures of anthropometry and metabolic status.

Methods

We applied maximum likelihood factor analysis to identify common latent factors underlying observed covariance in multiple obesity-related measures. Both the genetic components and the mode of inheritance of the common factors were evaluated. A total of 1775 participants from 590 families for whom measures on obesity-related traits were available were included in this study.

Results

The average age of participants was 37 years, 39% of the participants were obese (body mass index ≥ 30.0 kg/m²) and 26% were overweight (body mass index 25.0 - 29.9 kg/m²). Two latent common factors jointly accounting for over 99% of the correlations among obesity-related traits were identified. Complex segregation analysis of the age and sex-adjusted latent factors provide evidence for a Mendelian mode of inheritance of major genetic effect with heritability estimates of 40.4% and 47.5% for the first and second factors, respectively.

Conclusions

These findings provide a support for multivariate-based approach for investigating pleiotropic effects on obesity-related traits which can be applied in both genetic linkage and association mapping.

Inheritance of six anthropometric traits in Vaidyas of West Bengal, India

BACKGROUND

Anthropometric traits are important quantitative traits used by biological anthropologists. Surprisingly little is known about their pattern of inter-generational transmission, probably due to lack of use of developed statistical analysis in previous studies.

AIM

The present study is an attempt to approach the problem of the inheritance of anthropometric traits through advanced statistical applications.

SUBJECTS AND METHODS

Measurements of 824 individuals from 200 families including two generations were collected from Barasat, West Bengal. The study includes age correction by regression, familial correlation, heritability estimation and segregation analyses.

RESULTS

Results showed that there is strong involvement of the familial component in variation of anthropometric traits. The magnitude of heritability (h2= 57-83%) also supports their strong genetic basis. The results indicated that additive genes are not the only contributing factor; the effect of environment is considerable and that of dominant genes not negligible. Due to genetic interaction with the local environment (specific for each trait), heritabilities vary from one trait to another. Length measurements have higher heritability than breadth measurements. Segregation analysis revealed that either the additive or dominant major gene (MG) is responsible for this effect, which follows simple Mendelian transmission. Beside this, the possibility of the existence of an additional minor gene cannot be discarded.

CONCLUSION

Anthropometric traits have a genetic basis but their mode of inheritance is quite complex in nature. There is evidence of major gene effect (along with polygenes) with Mendelian transmission.

Genetic and environmental determinants of circulating resistin level in a community-based sample

OBJECTIVE

Resistin is a hormone secreted by adipose tissue, monocytes, bone marrow, and other tissues. It was also proclaimed as an important link between obesity and diabetes. The main objective of this study was to elucidate the contribution of a number of endogenous factors, such as sex, age, obesity characteristics, and genetic effects to the production of resistin in apparently healthy individuals. We also tested the possible relationships between circulating levels of resistin and other adipokines (leptin, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha)).

MEASUREMENTS

The plasma levels of studied adipokines were determined by enzyme-linked immunoassay in pedigree-based sample (n = 616), and subjected to model-based quantitative genetic analysis.

RESULTS

Resistin levels were significantly higher in women than in men (3.60 +/- 2.53 vs 3.15 +/- 2.48 ng/ml, P < 0.001), and varied independently of age in either sex. Statistical-genetic analysis revealed significant familial correlations (P < 0.01) for resistin. Adjusted for covariates, 66.38 +/- 10.28% of the resistin variation was attributable to putative genetic factors. A relatively small portion of the resistin variation (11.54 +/- 5.77%) was attributable to sharing a common household environment. The remaining variation, 22.12 +/- 17.69% was due to random environmental (i.e., unmeasured non-additive genetic) effects. The results of our analysis showed modest significant correlation of resistin with TNF-alpha and IL-6, and only in some groups; thus, while resistin was correlated with TNF-alpha in men, the correlation with IL-6 was significant only in the post-menopausal women group.

CONCLUSIONS

Our observations indicate that resistin is strongly influenced by genetic factors. The high heritability estimates for resistin concentrations clearly suggest the continuing need for further molecular genetic investigations.

Padrões de adiposidade em mulheres atendidas em um Centro Municipal de Saúde de Belo Horizonte, 2000

O objetivo do estudo consiste em definir padrões de adiposidade em mulheres. O estudo foi realizado em um Centro Municipal de Saúde de Belo Horizonte, Minas Gerais, com 827 mulheres entre 12 e 65 anos. As participantes realizaram diversas medidas antropométricas e responderam a um questionário sobre condições socioeconômicas, demográficas, história obstétrica, estilo de vida. A técnica de análise fatorial de componentes principais (ACP) foi utilizada para identificar conglomerados e independência de variáveis antropométricas na definição de padrões de adiposidade em mulheres. Os três primeiros componentes principais independentes explicaram 85,97% da variância. O primeiro foi representado pelas pregas cutâneas, o segundo pelo Índice de Massa Corporal (IMC) e pela circunferência do braço (CB) e o terceiro pela razão cintura/quadril (RCQ). Os fatores explicaram 38,42%, 29,03% e 18,52% da inércia, respectivamente. Evidenciou-se associação positiva entre todas as variáveis. Observou-se associação de maior intensidade, justificado pela alta correlação, entre as pregas da coxa, peitoral, bicipital, subescapular e supra-ilíaca (Fator 1) e a CB e o IMC (Fator 2). A variável RCQ foi identificada como principal representante do terceiro fator. Conclui-se que a análise fatorial de componentes principais identificou adequadamente três padrões de adiposidade em mulheres: periférica, global e central. A forte associação entre o IMC e CB demonstra que essa última medida poderia substituir com vantagens o IMC no rastreamento populacional da obesidade. Os critérios diagnósticos para a obesidade em mulheres seriam mais precisos se considerassem simultaneamente a CB, a RCQ e a prega da coxa.

A genome-wide linkage scan for quantitative trait loci underlying obesity related phenotypes in 434 Caucasian families

To identify quantitative trait loci (QTLs) that contribute to obesity, we performed a large-scale whole genome linkage scan (WGS) involving 4,102 individuals from 434 Caucasian families. The most pronounced linkage evidence was found at the genomic region 20p11-12 for fat mass (LOD = 3.31) and percentage fat mass (PFM) (LOD = 2.92). We also identified several regions showing suggestive linkage signals (threshold LOD = 1.9) for obesity phenotypes, including 5q35, 8q13, 10p12, and 17q11.

Indices of body composition and chronic morbidity: a cross-sectional study of a rural population in central Russia

Our objective was to clarify how different groups of chronic morbidities are associated with indices of body composition, such as body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR), skinfold index (SF), and fat-free mass index (FFMI). Our sample comprised Chuvasha residing in numerous villages in a rural area of the Russian Federation. The investigated cohort included 787 males aged 18-89 years, and 716 females aged 18-90 years. We performed a cross-sectional, community-based study of a large sample of individuals not receiving any medications for treatment or prevention of chronic morbidities. To elucidate the association between morbidity and age-adjusted anthropometrical indices, we used one-way analysis of variance, wherein the above indices were the dependent variables, while individuals affected vs. nonaffected for a specific disease were the grouping variables. Individuals with ischemic heart disease, diabetes mellitus, hypertension, and peptic ulcer showed significant differences in their BMI, WC, WHR, and SF. In the first diseases, mean values of anthropometric indices were higher in affected individuals, whereas in the peptic ulcer group, mean values were higher in the nonaffected. Skin diseases and gynecological diseases showed significant differences in WHR. Mean values in affected individuals were lower than in the nonaffected. The group afflicted with local forms of arthritis showed significant differences in FFMI, suggesting that arthritis is not linked to obesity, but is linked to high lean mass. Rheumatic diseases positively correlated with WC and FFMI.

Sex- and age-related variations of the somatotype in a Chuvasha population

The aim of this large, cross-sectional study was to describe the age- and sex-related variations of the somatotype, employing Heath and Carter's method, in a Chuvasha population residing in a rural region in central Russia. The investigated sample included 802 males aged 18-89 years (mean 46.9) and 738 females aged 18-90 years (mean 48.6). We evaluated the age and sex differences by one-way ANOVA with somatotype components as dependent variables and sex or age groups as grouping variables. Sex differences of somatotypes appear to be the strongest for endomorphy, with generally higher values in women. Endomorphy in males remained virtually unchanged after 30 years of age, but endomorphy in females kept increasing up to the 6th decade, and then subsequently decreased. Virtually no differences were noted in mesomorphy and a very small difference in ectomorphy between males and females aged 18-30 years. A reduction of sexual dimorphism in all somatotype components after age 70 was also observed. The largest difference of all somatotype components appeared between age groups 18-30 and 31-40 years. Thereafter, somatotypes remained practically unchanged. Mesomorphy continued to increase until the 5th decade in both sexes, while in females, endomorphy continuously increased until their 6th decade. In the 7th and 8th decades, a decrease in mean values was observed. Mesomorphy and ectomorphy showed opposite age-related trends. Results of our study clearly suggest that in physique investigations, the somatotypes need to be studied in each sex separately, and in studies of young people, they need also to be adjusted to age.

Complex segregation analysis of quantitative dermatoglyphic traits in five Indian populations

OBJECTIVE

Dermatoglyphics is widely used as a genetically determined trait in anthropogenetics although the genetic nature of its inheritance is still inconclusive, due to the lack of any established genetic model to resolve the existing inconsistencies in the literature. However, advanced statistical packages for complex segregation analyses are available and the aim of the present study is to determine the mode of dermatoglyphic trait inheritance in five different ethnic populations.

METHODS

Five hundred families (2435 individuals) of two generations were used for principal component analysis, familial correlation and segregation analysis (package MAN-5).

RESULTS

The similarity of three factors suggests a common internal structure. Significant familial correlation (except spouse) indicates the involvement of a familial component in the variation of dermatoglyphic traits. Segregation analyses suggest the transmission of a genetic effect in the families which follows the Mendelian model and confirms a major gene effect on factor 1 and factor 2 with two co-dominant alleles. There is no evidence of a major gene effect or environmental effect on factor 3 (a-b ridge counts). The nature of transmission and trait variance (H2) strongly supports the existence of a common nature of dermatoglyphic trait inheritance in populations, irrespective of ethnic and geographic area.

CONCLUSION

Major gene involvement in finger dermatoglyphics according to Mendelian models is confirmed.

Association of leptin levels with obesity and blood pressure: possible common genetic variation

OBJECTIVE

To ascertain the extent to which relationships between obesity (OB) and blood pressure (BP) can be explained by an individual's leptin plasma levels.

DESIGN

Pedigree-based cross-sectional study in an apparently healthy population of European origin.

SUBJECTS

The study sample is comprised of 90 nuclear and more complex families totaling 210 male and 213 female subjects aged 18-75 y, randomly recruited in Bashkorstan Autonomic region, Russia.

MEASUREMENTS

Various fatness and fat distribution traits (including nine circumferences (CRCs), and eight skinfolds (CKFs) by anthropometry), blood pressure, and plasma leptin levels (by ELISA kits).

RESULTS

Adjustment for circulating leptin led to attenuation of the magnitude of correlations between OB and BP, regardless of trait pair and sex cohort. Some of these correlations became statistically nonsignificant. All familial effects were gone, and heritability estimates became virtually zero after adjustment of each of the OB traits and systolic blood pressure (SBP) in offspring for leptin values in parents.

CONCLUSION

BP and OB covariation is substantially mediated by circulating leptin levels. As a result, body fat has only a weak independent effect on BP variation after adjustment for leptin levels. Our findings also strongly suggest that genetic variation in body mass index, SKFs, and even body CRCs, as well as of SBP is due to genetic variation of leptin. Genetic variation of diastolic blood pressure in the present sample, however, shared very little with that of leptin.

Somatotype and disease prevalence in adults

We examined the association between the somatotype and its main components (endomorphy, mesomorphy and ectomorphy), and the prevalence of several chronic diseases. The data were obtained from a cross-sectional survey designed to assess somatotype and morbidity with special reference to most often diagnosed diseases. The study population comprised 524 men and 250 women. The subjects underwent laboratory tests and clinical and anthropometric examinations. Of all examined workers, 94.8% fell into the five somatotype categories; of these, 394 were endomorphic mesomorphs. The most common somatotype was endomorphic mesomorph for men and mesomorph-endomorph for women. In five disease groups, prevalence was significantly related to a somatotype. Mesomorphic endomorphs most frequently suffered from digestive system diseases (40.6%, p < 0.05), neuroses (30.1%, p < 0.05), and radiculitis lumbosacralis (15.4%). The prevalence of arterial hypertension in mesomorph-endomorphs (37.1%), endomorphic mesomorphs (35.5%), and mesomorphic endomorphs (34.3%) was equal. In both genders, those with the highest endomorphy and mesomorphy and the lowest ectomorphy, grouped by cluster analysis, were those who suffered most frequently from arterial hypertension and liver disease. The authors conclude that the somatotype having a dominant mesomorphy and marked endomorphy constitutes a risk factor as a particular predisposition toward certain diseases and requires body weight control.

Evidence for common controls over inheritance of bone quantity and body size from segregation analysis in a pedigreed colony of nonhuman primates (Macaca nemestrina)

The genetic determinants of bone mineral quantity and body size and their postulated interaction are just beginning to be elucidated. The heritability of bone quantity and its relationship to components of body size were therefore investigated using segregation analysis applied to a large pedigreed nonhuman primate (Macaca nemestrina) breeding colony. The colony consisted of 216 females and 16 males with uniform dietary histories, environmental conditions, and rearing of offspring apart from the mother to minimize familial aggregation. Bone quantity (bone mineral content and spinal areal density) was measured by dual-energy X-ray absorptiometry (DXA). Size included measures of body mass, length, breadth, and a composite index. Body mass was determined from both body weight and lean body mass by DXA. Length was assessed by measuring trunk and thigh lengths, and breadth by measuring chest circumference and bitrochanteric width. A composite index of size was also calculated from a linear function of trunk and thigh lengths, chest circumference and bitrochanteric width, and lean body mass. Traits of bone quantity and size were highly correlated (r = 0.56-0.96, p < 0.001). Significant (p < or = 0.03) univariate heritabilities were found for spine bone mineral density (SPBMD; h(2) = 0.66) and whole body bone mineral content (WBBMC; h(2) = 0.40) and size measures of length (trunk h(2) = 0.71, thigh h(2) = 0.65), breadth (bitrochanteric width h(2) = 0.31), lean body mass (LEAN; h(2) = 0.37), and the composite index of size (SIZE-PC, h(2) = 0.49) adjusted for demographic variables. The data were also subjected to an analysis of bivariate genetic correlations and factor analysis, both of which suggested a robust interaction between body size and bone quantity. Bivariate genetic correlations between body size and the bone quantities WBBMC, SBMD, and spine bone mineral content (SPBMC) were high (e.g., using LEAN as a measure of size, r = 0.57, 0.41, and 0.57, respectively). Factor analysis showed that 80% of the phenotypic and 72% of the genetic variances of all traits were accounted for by a single factor, suggesting common genetic controls operative over bone quantity and size.

Human obesity: an evolutionary approach to understanding our bulging waistline

The unique worldwide spread of the human species and the remarkably long post-reproductive survival show that our genome permits excellent adaptation to vastly different environments. Moreover, the main scourges of later age, namely malignant growths and atherosclerosis, appear in humans later than in shorter-living animals. In recent years, excess weight and obesity have become mass phenomena with a pronounced upward trend in all developed countries. However, despite the detrimental effects of being overweight, these populations live longer than ever, which in part may be explained by the availability of better medical treatment. The prevalence and predicted further spread of obesity can be understood in the light of evolution. In all animal species energy metabolism is asymmetric with energy accumulation ('thrifty genotype') being the necessary condition of survival during hard times. For humans, which are no different to other animals in this respect, this genetic programming was necessary for survival because during the course of history, including the recorded history in the more developed Middle East, Europe or China, there was never a long period of uninterrupted food abundance, whereas famines were regular and frequent. Therefore fat accumulation, when food was available, meant survival at times of shortage, while the possible detrimental effects of overindulgence in food and being overweight expressed in unrealistically old age were irrelevant. It is the central, mostly intra-abdominal fat (in both humans and animals) that is more medically important than the subcutaneous truncal fat, and the accumulation of both types of fat is conditioned by high food consumption; therefore it is a historic novelty for human populations. In contrast, lower-body fat in human females is unique in the animal kingdom: it is much less metabolically active, it is of much lower pathologic significance than central fat, and it is programmed to be mobilized mostly during pregnancy and lactation. In view of all this, norms of desired weight should be based on hard mortality and morbidity statistics and not on theoretical, esthetic or fashion considerations. By this criterion, the upper limit of desirable weight is likely to be body mass index (BMI) 27 or 28, but specified for different populations (sex, race, ethnic origin); moreover, with aging, the detrimental effects of obesity diminish and finally disappear. Risks of other pathologies related to obesity (e.g. diabetes, hypertension and coronary disease) are also population-specific. However, total fatness, measured by BMI, is insufficiently sensitive as a risk factor, and fat distribution (upper-body versus low-body type, as reflected by waist circumference and waist:hip ratio) plays at least as prominent a role. Therefore the detailed norms, not yet available, should take into account both general obesity and fat distribution and be specific for different populations. Since long-term weight loss in adults is rarely achievable, public health measures should be aggressively directed at the prevention of obesity from childhood.

Evidence for a major gene influence on abdominal fat distribution: the Minnesota Breast Cancer Family Study

Abdominal fat has been shown to be an important risk factor for many chronic conditions, including diabetes, heart disease, and breast cancer. The objective of this study was to provide evidence for a major gene influence on the ratio of waist to hip circumference (WHR), a measurement commonly used in large scale studies to indicate the presence of abdominal fat. Segregation analysis was conducted on three subsets of families from the Minnesota Breast Cancer Family Study. One analysis was conducted among families with WHR measurements on all women. Two additional analyses were conducted on subsets of women stratified on menopausal status. Multiple regression analysis was used to identify factors associated with WHR expressed as a continuous trait. Complex segregation analyses were performed on the continuous trait of WHR and the covariates identified in the regression analysis. In the analysis of all women, all hypotheses were rejected. Among premenopausal women, the environmental hypothesis with no heterogeneity between generations fit the data best (P = 0.85). However, among postmenopausal women, the requirements for conclusion of the presence of a major gene were met. All non-Mendelian hypotheses were rejected (P < 0.0001), but the additive hypothesis was not rejected (P = 0.19) and provided the best fit to the data. The putative major gene identified by this model accounted for 42% of total phenotypic variance in WHR among these postmenopausal women. The allele for high WHR had a frequency of 27%. These findings support the hypothesis that the distribution of abdominal fat in postmenopausal women is under genetic control.

Familial factors of blood pressure and adiposity covariation

In the present study, we used the maximum likelihood approach as implemented by variance analysis and attempted to quantify genetic and environmental components of variance in systolic (SBP) and diastolic (DBP) blood pressure in 514 individuals who belonged to a total of 135 nuclear families of Chuvasha, Russia, ethnic origin. The extent to which these interindividual differences depend on age, gender, body mass index (BMI) and other anthropometric measurements was investigated. Major findings include the following. (1) The variation in both SBP and DBP was significantly affected by genetic factors (h(2)(SBP)=0.51+/-0.13, h(2)(DBP)=0.20+/-0.09), shared household environment, and age. These effects were stronger with respect to SBP, which also showed significant gender differences in baseline values and rate of SBP increase with age. (2) Genetic and common household factors, as well as undetected residual effects, were not completely independent. The respective 3 facets of correlation between SBP and DBP were significant: 0.66+/-0.10, 0.76+/-0.11, and 0.55+/-0.14. (3) SBP and DBP each showed significant phenotypic correlations with BMI and anthropometric factors. These correlations had a substantial genetic component but were not equal for SBP and DBP. SBP showed the highest genetic correlation with arm circumference (r(G)=0.63), whereas for DBP, this was found with hip skinfold (r(G=)0.88). (4) Bivariate heritability estimates, as well as adjustment of BP measurements for BMI and selected anthropometrics, indicated that DBP likely does not have independent genetic heritability. The residual genetic variance of adjusted SBP remained significant, although substantially lower in comparison with the nonadjusted h(2).

Comparison of anthropometric characteristics between normotensive and hypertensive individuals among a population of Bengalee Hindu elderly men in Calcutta, India

A comparative investigation of 99 normotensive and 111 hypertensive Bengalee Hindu elderly men (aged 55 years and above) of Kalighat, South Calcutta, India, was undertaken to study differences in levels of adiposity, body fat distribution and body composition between these two groups. Results revealed that there were significant differences between normotensive (NT) and hypertensive (HT) subjects in the mean values for weight (p < 0.05), body mass index (BMI, p < 0.01); waist (p < 0.001) and hip circumferences (p < 0.05); waist-hip ratio (WHR, p < 0.001), conicity index (CI, p < 0.01) and fat free mass (FFM, p < 0.001). Percentile distributions for all these variables and indices showed consistently higher values among the HT patients as compared with NT subjects. However, the frequency of obesity (BMI > or = 25) was similar (NT = 6.1%, HT = 11.7%) in both groups. Thus, these results indicated that there existed significant differences in central adiposity and FFM between NT and HT subjects although their level of obesity was similar. Hypertensive individuals have significantly enhanced levels of central body fat distribution.

Hematological and pulmonary responses to high altitude in Quechuas: a multivariate approach

This study investigates the relationships among hematological variables, pulmonary function, and age in a sample of high-altitude natives. The following anthropometric and physiological variables were examined in 77 adult Quechua males from the Peruvian Central Andes (Huancavelica, 3,680 m): height, weight, sitting height, chest diameters, chest and abdominal circumferences, forced vital capacity (FVC), forced expiratory volume at 1 sec (FEV1), peak expiratory flow (PEF), hemoglobin concentration (Hb), red blood cells (RBC), hematocrit (Htc), diastolic and systolic blood pressure, body temperature, pulmonary rate, and pulse rate. The means of these variables for the Huancavelica sample fall within the range of variability previously observed in Andean populations. Principal components analysis and canonical correlation analysis suggest that in this native Andean population: 1) aging decreases lung function but does not affect hematological features, and 2) there is a negative age-independent correlation between lung function (FVC, FEV1, PEF) and hematological traits (Hb, RBC, Htc).

Genetics of human body size and shape: evidence for an oligogenic control of adiposity

In a previous study by the authors in each of the pedigree samples from Kirghizstan, Turkmenia and Chuvashia, four principal factors supposedly controlled by four non-overlapping gene subsets were found. About 90% of total variation of adiposity as assessed by 22 measurements of skinfolds, circumferences and indices were covered by these factors. This study provides results of segregation analysis of each of these four factors. By the usual transmission probability tests, major gene (MG) control was accepted in all 12 analyses--four traits in three populations. Some of the most parsimonious MG models included non-MG effects, such as correlation of residuals between spouses, between parent and offspring and between sibs. The Kirghizian samples showed a significant assortative mating effect as measured by the correlation between genotypic values at putative MG in spouses. The proportion of the trait variance attributable to the MG effect varied from 0.296 (factor F4 in the Chuvashia sample) to 0.596 (the same factor in the Kirghizian sample). It is assumed that four independent large-effect genes can be recognized in the genetic control of adiposity determining, respectively, individual predisposition to accumulate subcutaneous fat, its distribution between the body trunk and extremities, predisposition to accumulate inner fat and its distribution between the upper and lower body parts. In each population, unification of the four most parsimonious MG models forms oligogenic models explaining from 0.364 (Chuvashia) to 0.540 (Kirghizstan) of total adiposity.