According to the 'good genes' hypothesis, females choose males based on traits that indicate the male's genetic quality in terms of disease resistance. The 'immunocompetence handicap hypothesis' proposed that secondary sexual traits serve as indicators of male genetic quality, because they indicate that males can contend with the immunosuppressive effects of testosterone. Masculinity is commonly assumed to serve as such a secondary sexual trait. Yet, women do not consistently prefer masculine looking men, nor is masculinity consistently related to health across studies. Here, we show that adiposity, but not masculinity, significantly mediates the relationship between a direct measure of immune response (hepatitis B antibody response) and attractiveness for both body and facial measurements. In addition, we show that circulating testosterone is more closely associated with adiposity than masculinity. These findings indicate that adiposity, compared with masculinity, serves as a more important cue to immunocompetence in female mate choice.
Cites: JAMA. 1999 Oct 27;282(16):1523-910546691
Cites: Nature. 1998 Aug 27;394(6696):884-79732869
Cites: Ann Intern Med. 1993 Oct 1;119(7 Pt 2):655-608363192
Cites: Proc Biol Sci. 1998 May 22;265(1399):927-339633114
To examine the associations of maternal diabetes, overall and stratified according to treatment of diabetes, with weight-related outcomes at the time of military conscription, at age 18-20 years.
Cohort study of 277 Danish male offspring of mothers with recognized pre-gestational or gestational diabetes. As population-based controls we selected 870 men matched from the Civil Registration Office.
Data on weight-related outcomes were retrieved from the Danish military conscription registry.
Military rejection due to adiposity and body mass index (BMI) at conscription.
Army rejection rate due to adiposity was 5.8% (n= 16) among 277 diabetes mellitus-exposed men compared with 3.1% (n= 27) in 870 controls (risk difference 2.7 (95% confidence interval (CI) -0.3-5.7)) and mean BMI at conscription was 1.4 kg/m(2) (95%CI 0.8-2.0) higher among those diabetes mellitus-exposed men. In analyses adjusted for birthweight and gestational age, compared with controls, the BMI was 0.6 kg/m(2) (95%CI -0.3-1.5) higher in sons of mothers with pre-gestational and 2.7 kg/m(2) (95% (CI): 0.9-4.5) higher with gestational diabetes. The greatest BMI difference was in offspring of mothers with gestational diabetes in whom insulin was initiated during pregnancy. We found no difference in conscript height.
Compared with controls, male offspring of women with diabetes had a higher rejection rate due to adiposity and higher adult BMI. Subgroup analyses showed that the association was most pronounced in sons of mothers with gestational diabetes, whereas pre-gestational diabetes was only weakly associated with higher offspring BMI.
Human adiposity is highly heritable, but few of the genes that predispose to obesity in most humans are known. We tested candidate genes in pathways related to food intake and energy expenditure for association with measures of adiposity.
We studied 355 genetic variants in 30 candidate genes in 7 molecular pathways related to obesity in two groups of adult subjects: 1,982 unrelated European Americans living in the New York metropolitan area drawn from the extremes of their body mass index (BMI) distribution and 593 related Yup'ik Eskimos living in rural Alaska characterized for BMI, body composition, waist circumference, and skin fold thicknesses. Data were analyzed by using a mixed model in conjunction with a false discovery rate (FDR) procedure to correct for multiple testing.
After correcting for multiple testing, two single nucleotide polymorphisms (SNPs) in Ghrelin (GHRL) (rs35682 and rs35683) were associated with BMI in the New York European Americans. This association was not replicated in the Yup'ik participants. There was no evidence for gene x gene interactions among genes within the same molecular pathway after adjusting for multiple testing via FDR control procedure.
Genetic variation in GHRL may have a modest impact on BMI in European Americans.
Cites: Int J Circumpolar Health. 2005 Jun;64(3):281-9016050322
Cites: N Engl J Med. 1999 Oct 7;341(15):1097-10510511607
Genome-wide association studies (GWAS) have identified common genetic factors influencing body mass as well as body adiposity. The functional implications of these loci are currently under investigation. Intense scrutiny of the body mass-associated FTO locus revealed age-specific effects, or a weakened effect in elderly populations. In this study, we aimed to determine the effects of single nucleotide polymorphisms (SNPs) representing 35 GWAS-identified body mass- and adiposity-associated genetic loci. In our analysis, 949 participants of the Prospective Investigation of the Vasculature in Uppsala Seniors cohort were included. All participants were born between 1920 and 1924. Data were available for 474 male and 475 female participants at age 70 and 380 male and 390 female participants at age 75. Genetic associations with BMI and change in BMI from age 70 to 75 were analyzed. In our analysis, rs10968576, an intronic SNP within the LINGO2 (LERN3, LRRN6C) gene, was associated with body mass in a cross section of elderly Swedes at age 70. This is the first study to replicate the association of a LINGO2-related genetic variant with body mass in an independent cohort of elderly citizens.
Exercise behavior, cardiorespiratory fitness, and obesity are strongly influenced by genetic factors. By studying young adult twins, we examined to what extent these interrelated traits have shared genetic and environmental etiologies. We studied 304 twin individuals selected from the population-based FinnTwin16 study. Physical activity was assessed with the Baecke questionnaire, yielding three indexes: sport index, leisure-time index, and work index. In this study, we focused on sport index, which describes sports participation. Body composition was determined using dual-energy X-ray absorptiometry and cardiorespiratory fitness using a bicycle ergometer exercise test with gas exchange analysis. The Baecke sport index was associated with high maximal oxygen uptake adjusted for lean body mass (Vo(2max)[adj]) (r = 0.40), with low body fat percentage (BF%) (r = -0.44) and low waist circumference (WC) (r = -0.29). Heritability estimates for the key traits were as follows: 56% for sport index, 71% for Vo(2max)[adj], 77% for body mass index, 66% for WC, and 68% for BF%. The association between sport index and Vo(2max) was mostly explained by genetic factors (70%), as were both the association between sport index and BF% (71%) and that between sport index and WC (59%). Our results suggest that genetic factors explain a considerable part of the associations between sports participation, cardiorespiratory fitness, and obesity.
Bone mineral density (BMD) and bone strength are predictive parameters for the development of osteoporosis and related fracture later in life. Although it is well known that BMD and bone strength have a high heritability, not much of the variation is already explained. Mice models showed that sFRP1 has an influence on bone formation. Therefore this study aimed to investigate the effect of common genetic variation on BMD and bone strength in Caucasian men of different ages. Using HapMap we selected 13 tagSNPs which tag most common genetic variation in and around sFRP1 and we genotyped these SNPs in the young cohort of the Odense Androgen Study (OAS). The OAS includes a total of 1383 Danish men from two different age groups ([20-29 years]: N=783; [60-74 years]: N=600) and is well characterised. The subjects were phenotyped for BMD at several sites, and additionally for body composition and hip geometry parameters. Based on the results of the young cohort we selected three SNPs for further analysis in the complete OAS population. To conclude we tried to replicate the results of two SNPs in an independent population of 994 Belgian men. We found a strong association for rs9694405 with BMI as well in both cohorts separately as in the whole OAS population. Further we found rs4736965 associated with several hip geometry parameters in the same population. However we were not able to replicate those results in the Belgian population. At last we found in the OAS population age specific effects for rs10106678 with whole body BMD and waist to hip ratio.
In older adults, mobility limitations often coexist with overweight or obesity, suggesting that similar factors may underlie both traits. This study examined the extent to which genetic and environmental influences explain the association between adiposity and mobility in older women. Body fat percentage (bioimpedance test), walking speed over 10 m, and distance walked in a 6-min test were evaluated in 92 monozygotic (MZ) and 104 dizygotic (DZ) pairs of twin sisters reared together, aged 63-76 years. Genetic and environmental influences on each trait were estimated using age-adjusted multivariate genetic modeling. The analyses showed that the means (and s.d.) for body fat percentage, walking speed, and walking endurance were 33.2+/-7.3%, 1.7+/-0.3 m/s and 529.7+/-75.4 m, respectively. The phenotypic correlation between adiposity and walking speed was -0.32 and between adiposity and endurance it was -0.33. Genetic influences explained 80% of the association between adiposity and speed, and 65% of adiposity and walking endurance. Cross-trait genetic influences accounted for 12% of the variability in adiposity, 56% in walking speed, and 34% in endurance. Trait-specific genetic influences were also detected for adiposity (54%) and walking endurance (13%), but not speed. In conclusion, among community-living older women, an inverse association was found between adiposity and mobility that was mostly due to the effect of shared genes. This result suggests that the identification of genetic variants for body fat metabolism may also provide understanding of the development of mobility limitations in older women.
Most genome-wide association studies are confined to middle-aged populations. It is unclear whether associations between single nucleotide polymorphisms (SNPs) and obesity persist in old age. We aimed to relate 10 body mass index (BMI)-associated SNPs to weight, BMI, % fat, visceral and subcutaneous adipose tissue in Health ABC and AGES-Reykjavik comprising 4,846 individuals of European Ancestry, and 1,139 African Americans over age 65. SNPs were scaled using effect estimates from candidate SNPs. In Health ABC, a SNP near GNPDA2 was modestly associated with weight and SAT area (p = .008, p = .001). Risk score (sum of scaled SNPs) was associated with weight, BMI, and SAT area (p
Cites: Nat Genet. 2010 Nov;42(11):949-6020935629
Cites: Lancet. 2010 Oct 23;376(9750):1393-40020971364
The joint effects of cardiorespiratory fitness (CRF) and body composition on metabolic health are not well known.
To examine the associations of CRF, fat-free mass index (FFMI), and fat mass index (FMI) with metabolic health in individual twins and controlling for genetic and shared environmental effects by studying monozygotic intrapair differences.
Two cross-sectional samples of healthy adult monozygotic and dizygotic twins were drawn from population-based Danish and Finnish national twin registries (n = 996 and n = 309).
CRF was defined as VO2max divided by fat-free mass. Insulin sensitivity and acute insulin response indices were derived from an oral glucose tolerance test. A continuous metabolic syndrome score was calculated. Visceral and liver fat were measured in the Finnish sample. Associations were analyzed separately in both cohorts with multivariate linear regression and aggregated with meta-analytic methods.
Insulin sensitivity, acute insulin response, metabolic syndrome score, visceral, and liver fat amount had strong and statistically significant associations with FMI (
0.53 to 0.79), whereas their associations with CRF and FFMI were at most weak (
0.02 to 0.15). The results of the monozygotic intrapair differences analysis showed the same pattern.
Although FMI is strongly associated with worsening of metabolic health traits, even after controlling for genetic and shared environmental factors, there was little evidence for the effects of CRF or FFMI on metabolic health. This suggests that changing FMI rather than CRF or FFMI may affect metabolic health irrespective of genetic or early environmental determinants.
FTO is the first gene established as contributing to common forms of obesity. The gene is highly expressed in the hypothalamus and is thought to mediate this effect through its influence on energy homeostasis. The hypothalamus, however, also regulates blood pressure (BP). Therefore, we investigated whether the FTO-risk variant is associated not only with increased adiposity but also with elevated BP and whether the latter may be mediated, in part, by increased sympathetic modulation of vasomotor tone.
The primary study was carried out in 485 adolescents recruited from a French Canadian founder population who underwent detailed body-composition and cardiovascular phenotyping. Body fat was examined with MRI, bioimpedance, and anthropometry. BP was recorded beat to beat at rest and during physical and mental challenges. Sympathetic modulation of vasomotor tone was assessed with power spectral analysis of BP. We found that individuals with the FTO-risk genotype compared with those without it demonstrate greater adiposity, including the amount of intra-abdominal fat (by 38%). They also showed higher systolic BP throughout the entire protocol, with a maximum difference during a mental stress (6.4 [1.5 to 11.3] mm Hg). The difference in BP was accompanied by elevated index of sympathetic modulation of vasomotor tone. A replication in an independent sample of adults from the same founder population confirmed the association between FTO and BP.
These results suggest that, in a French Canadian founder population, FTO may increase not only risk for obesity, as demonstrated in other populations, but also for hypertension. The latter may be related, at least in part, to the regulation of sympathetic vasomotor tone.