Genetic Epidemiology of BMI and Body Mass Change From Adolescence to Young Adulthood

The complex interplay between genes and environment affecting body mass gain over lifecycle periods of risk is not well understood. We use longitudinal sibling cohort data to examine the role of shared household environment, additive genetic, and shared genetic effects on BMI and BMI change. In the National Longitudinal Study of Adolescent Health, siblings and twin pairs sharing households for ≥10 years as adolescents (N = 5,524; mean = 16.5 ± 1.7 years) were followed into young adulthood (N = 4,368; mean = 22.4 ± 1.8 years). Using a variance component approach, we quantified genetic and household effects on BMI in siblings and nonsiblings sharing household environments over time. Adjusting for race, age, sex, and age‐by‐sex interaction, we detected a heritability of 0.43 ± 0.05 for BMI change. Significant household effects were noted during the young adulthood period only (0.11 ± 0.06). We find evidence for shared genetic effects between BMI and BMI change during adolescence (genetic correlation (ρ_G) = 0.61 ± 0.03) and young adulthood (ρ_G = 0.23 ± 0.06). Our findings support a complex etiology of BMI and BMI change.     

Associations of Aging and Birth Cohort with Body Mass Index in a Biethnic Cohort

Objective: To examine associations of aging and birth cohort with body mass index (BMI) in a biethnic cohort. Research Methods and Procedures: This was a longitudinal closed cohort study of 14, 500 white and African‐American men and women, 45 to 64 years of age, followed for 9 years. Aging was defined as the length of the interval in years between baseline and following visits. Birth cohort was defined by the year in which participants were born. Mixed model analyses were used to examine associations of aging, birth cohort, and BMI in four ethnicity‐gender groups. Results: We found that aging was associated with an increase in BMI in white and African‐American men and women. The associations between aging and BMI were stronger in the younger birth cohorts. Except for white women, younger birth cohort was associated with a higher BMI. After adjusting for aging, birth cohort was associated with an increase in BMI of 0.1 kg/m² [95% confidence interval (95% CI): ?0.1, 0.3] among white women. The corresponding values for African‐American women, white men, and African‐American men are 0.5 kg/m² (95% CI: 0.1, 0.9), 0.6 kg/m² (95% CI: 0.4, 0.8), and 0.6 kg/m² (95% CI: 0.2, 1.0), respectively. Discussion: Our analyses show that, in all except white women, people in this age range who were born later have a higher BMI at the same attained age. In all groups, people who are born later gained more weight as they aged. In general, subjects ages 45 to 64 years gained weight as they aged 9 years.     

Body Mass Index Development from Birth to Early Adolescence; Effect of Perinatal Characteristics and Maternal Migration Background in a Swedish Cohort

Background

Well documented diversity in risk of developing overweight and obesity between children of immigrant and of native mothers, might be explained by different body mass index (BMI) development trajectories in relation to maternal and perinatal characteristics of offspring.

Objectives

To assess BMI development trajectories among children born to immigrant and to Swedish mothers from birth to adolescence in relation to perinatal characteristics.

Methods

A cohort of 2517 children born in Stockholm during 1994 to 1996 was followed with repeated measurement of height and weight at eleven time points until age 12 years. We estimated changes over time for BMI in relation to maternal and perinatal characteristics of offspring using mixed linear model analysis for repeated measure data.

Results

We observed a significant BMI change over time in children and time interaction with maternal migration status (P<0.0001). Estimated BMI over time adjusted for maternal and perinatal characteristics of offspring, showed slower BMI growth before age of 5, followed by an earlier plateau and steeper BMI growth after 5 years among children of immigrant mothers compared with children of Swedish mothers. These differences in BMI growth were more prominent among children with mothers from outside Europe.

Conclusion

Beside reinforcing early childhood as a crucial period in development of overweight, the observed slower BMI development at early childhood among children of immigrants followed by a steeper increase in BMI compared with children of Swedish mothers is important for further studies and for planning of preventive public health programs.     

Self-Esteem and Change in Body Mass Index over 3 Years in a Cohort of Adolescents

Self-esteem has been hypothesized to be lower in obese adolescents relative to their normal weight peers and to be an important factor in preventing or reversing obesity. The present study examined the relationship between obesity and self-esteem cross-sectionally and prospectively over three years in a cohort of 1278 adolescents in grades 7 to 9 at baseline. Cross-sectional analyses revealed an inverse association between physical appearance self-esteem and body mass index in both males and females. In females, body mass index was inversely associated with global self-esteem, close friendship, and behavioral conduct self-esteem. In males, body mass index was inversely associated with athletic and romantic appeal self-esteem. Prospectively, in females, physical appearance and social acceptance self-esteem at baseline were inversely related to body mass index three years later. Baseline self-esteem was unrelated prospectively to change in body mass index in males. All associations were modest in magnitude. These results suggest that in a middle class white sample of adolescents, self-esteem specific to physical appearance is modestly associated with body mass index. Low self-esteem does not appear to predict the development of obesity over time.     

Hair Toxic Element Content in Adult Men and Women in Relation to Body Mass Index

The primary objective of the current study was to estimate the hair toxic metal content in adults in relation to body mass index. A total of 1,229 persons including 719 women and 510 men were examined. All subjects were divided into two age groups: 1 and 2 periods of adulthood. All men and women were also subdivided into groups in relation to their values of body mass index (BMI): underweight, normal weight, overweight and obese. Hair aluminium (Al), beryllium (Be), cadmium (Cd), mercury (Hg), lead (Pb) and tin (Sn) content was evaluated using mass spectrometry with inductively coupled plasma. It has been shown that increase in body weight is accompanied by elevated hair cadmium content in women. At the same time, no significant alteration of hair cadmium concentration was observed in males. Higher values of scalp hair mercury and lead content were observed in men and women with increased body mass index independently of their age. BMI-related elevation of hair tin content was registered only in men of the first period of adulthood. A significant correlation between hair metal content and the values of BMI was observed for mercury independently of the gender of the subjects, whereas BMI values correlated significantly with hair cadmium levels in women and lead and tin levels in men. It has been also estimated that hair cadmium, mercury and lead levels in men exceed the respective values in women.     

Changes of Body Mass Index in Relation to Mortality: Results of a Cohort of 42,099 Adults

Background

High Body-Mass-Index (BMI) is associated with increased all-cause mortality, but little is known about the effect of short- and long-term BMI change on mortality. The aim of the study was to determine how long-term weight change affects mortality.

Methods and findings

Within a population-based prospective cohort of 42,099 Austrian men and women (mean age 43 years) with at least three BMI measurements we investigated the relationship of BMI at baseline and two subsequent BMI change intervals of five years each with all-cause mortality using Cox proportional Hazard models. During median follow-up of 12 years 4,119 deaths were identified. The lowest mortalities were found in persons with normal weight or overweight at baseline and stable BMI over 10 years. Weight gain (≥0.10 kg/m²/year) during the first five years was associated with increased mortality in overweight and obese people. For weight gain during both time intervals mortality risk remained significantly increased only in overweight (Hazard Ratio (HR): 1.39 (95% confidence interval: 1.01; 1.92)) and obese women (1.85 (95% confidence interval: 1.18; 2.89)). Weight loss (< −0.10 kg/m²/year) increased all-cause mortality in men and women consistently. BMI change over time assessed using accepted World Health Organisation BMI categories showed no increased mortality risk for people who remained in the normal or overweight category for all three measurements. In contrast, HRs for stable obese men and women were 1.57 (95% CI: 1.31; 1.87) and 1.46 (95% CI: 1.25; 1.71) respectively.

Conclusion

Our findings highlight the importance of weight stability and obesity avoidance in prevention strategy.     

Childhood Household Dysfunction,Social Inequality and Alcohol Related Illness in Young Adulthood. A Swedish National Cohort Study

The aim of this paper is to estimate the cumulative effect of childhood household dysfunction (CHD) on alcohol related illness and death later in life and to test the interaction between CHD and socioeconomic background. The study utilised Swedish national registers including data of a Swedish national cohort born 1973–82 (n = 872 912), which was followed from age 18 to 29–40 years. Cox regression analyses were used to calculate hazard ratios (HR) for alcohol related illness or death in young adulthood. The CHD measure consisted of seven indicators: parental alcohol/drug misuse, mental health problems, criminality, death, divorce, social assistance, and child welfare interventions. Childhood socioeconomic position (SEP) was indicated by parental occupational status. Outcomes were alcohol related inpatient hospital care, specialised outpatient care or deaths. Using the highest socioeconomic group without CHD experience as a reference, those in the same socioeconomic group with one indicator of CHD had HRs of 2.1 [95% CI: 1.7–2.5], two CHD indicators 5.6 [4.4–7.1], three or more indicators 9.4 [7.1–12.4] for retrieving inpatient care. Socioeconomic disadvantage further increased the risks–those with low socioeconomic background and three CHD indicators or more had a HR of 12.5 [10.9–14.3]. Testing for interaction suggests that the combined HRs deviates from additivity [Synergy index: 1.6, 95% CI: 1.4–1.9]. The results for outpatient care were similar, but not as pronounced. In conclusion, this Swedish national cohort study shows that childhood household dysfunction is strongly and cumulatively associated to alcohol related illness later in life and that it interacts with socioeconomic disadvantage.     

The Relationship of Childhood Adiposity to Parent Body Mass Index and Eating Behavior

Objective: To better understand risk factors for the development of obesity in early childhood, we examined the association between children's adiposity and their parents' eating behavior and body mass index (BMI). Research Methods and Procedures: Parents of 85 white children 36 months of age (49 boys and 36 girls) completed the Three‐Factor Eating Questionnaire measuring three dimensions of parent eating behavior: disinhibited eating, cognitive restraint of eating, and susceptibility to hunger. Parent BMI (kg/m²) was calculated using self‐reported height and weight. The children's percentage body fat was assessed by dual energy X‐ray absorptiometry analysis. Results: Twenty‐six percent of parents were obese (BMI ≥ 30 kg/m²). Both maternal and paternal BMI were associated with higher scores for disinhibition (r = 0.69 and r = 0.68, p < 0.001), and maternal BMI was also associated with higher scores for hunger (r = 0.51, p < 0.001). There were no significant relationships between children's percentage body fat and parent eating scores, and the correlation between children's percentage body fat and parent BMI was significant only between mothers and daughters (r = 0.35, p = 0.04). Obese parents were no more likely to have a child who was fatter (upper quintile of percentage body fat for gender). Discussion: Among 36 month‐old white children, parent eating behavior was related to parent BMI, but not to children's adiposity. There was only a weak relationship between parent BMI and child adiposity. Despite the aggregation of adiposity within families due to shared genes and environments, children may not express differences in susceptibility to obesity by 3 years of age.     

The Influence of Bereavement on Body Mass Index: Results from a National Swedish Survey

Background

Previous findings suggest that the loss of a family member is associated with health and mortality. The purpose of this study was to investigate the association between bereavement experiences and BMI, and whether there are socio-demographic differences in this association.

Objective

To investigate the association between bereavement experiences and BMI, and whether there are socio-demographic differences in this association.

Methods

We used cross-sectional data with retrospective questions from the Swedish Level of Living Survey (LNU) of 2000, including 5,142 individuals. The bereavement experiences examined in the study include the loss of a sibling, a parent or a spouse, and time since the death of a parent. BMI (kg/m²) was calculated using self-reported measurements of weight and height. The association between bereavement and BMI was evaluated through linear regressions.

Results

After controlling for possible confounders, most of the models detected an association between bereavement and BMI. The fully-adjusted model showed that loss of parents was associated with a 0.45 increase in BMI (SE = 0.20). The effect also seemed to be dependent on time since the loss and social class position.

Conclusions

The present study is the first to examine associations between different types of familial losses and BMI. We find an association between the death of a family member and BMI, but it appears to be related to time since the death, type of bereavement experience and social class.     

Aged-Related Changes in Body Composition and Association between Body Composition with Bone Mass Density by Body Mass Index in Chinese Han Men over 50-year-old

Objectives

Aging, body composition, and body mass index (BMI) are important factors in bone mineral density (BMD). Although several studies have investigated the various parameters and factors that differentially influence BMD, the results have been inconsistent. Thus, the primary goal of the present study was to further characterize the relationships of aging, body composition parameters, and BMI with BMD in Chinese Han males older than 50 years.

Methods

The present study was a retrospective analysis of the body composition, BMI, and BMD of 358 Chinese male outpatients between 50 and 89 years of age that were recruited from our hospital between 2009 and 2011. Qualified subjects were stratified according to age and BMI as follows: 50–59 (n = 35), 60–69 (n = 123), 70–79 (n = 93), and 80–89 (n = 107) years of age and low weight (BMI: < 20 kg/m²; n = 21), medium weight (20 ≤ BMI < 24 kg/m²; n = 118), overweight (24 ≤ BMI < 28 kg/m²; n = 178), and obese (BMI ≥ 28 kg/m²; n = 41). Dual-energy X-ray absorptiometry (DEXA) was used to assess bone mineral content (BMC), lean mass (LM), fat mass (FM), fat-free mass (FFM), lumbar spine (L1-L4) BMD, femoral neck BMD, and total hip BMD. Additionally, the FM index (FMI; FM/height²), LM index (LMI; LM/height²), FFM index (FFMI; [BMC+LM]/height²), percentage of BMC (%BMC; BMC/[BMC+FM+LM] × 100%), percentage of FM (%FM; FM/[BMC+FM+LM] × 100%), and percentage of LM (%LM; LM/(BMC+FM+LM) × 100%) were calculated. Osteopenia or osteoporosis was identified using the criteria and T-score of the World Health Organization.

Results

Although there were no significant differences in BMI among the age groups, there was a significant decline in height and weight according to age (p < 0.0001 and p = 0.0002, respectively). The LMI and FFMI also declined with age (both p < 0.0001) whereas the FMI exhibited a significant increase that peaked in the 80-89-years group (p = 0.0145). Although the absolute values of BMC and LM declined with age (p = 0.0031 and p < 0.0001, respectively), there was no significant difference in FM. In terms of body composition, there were no significant differences in %BMC but there was an increase in %FM (p < 0.0001) and a decrease in %LM (p < 0.0001) with age. The femoral neck and total hip BMD significantly declined with age (p < 0.0001 and p = 0.0027, respectively) but there were no differences in L1-L4. BMD increased at all sites (all p < 0.01) as BMI increased but there were declines in the detection rates of osteoporosis and osteopenia (both p < 0.001). A logistic regression revealed that when the medium weight group was given a BMI value of 1, a decline in BMI was an independent risk factor of osteoporosis or osteopenia, while an increase in BMI was a protective factor for BMD. At the same time, BMD in L1-L4 exhibited a significant positive association with FMI (p = 0.0003) and the femoral neck and total hip BMDs had significant positive associations with FFMI and LMI, respectively (both p < 0.0001).

Conclusions

These data indicate that LMI and FFMI exhibited significant negative associations with aging in Chinese Han males older than 50 years, whereas FMI had a positive association. BMD in the femoral neck and total hip declined with age but an increased BMI was protective for BMD. LMI and FFMI were protective for BMD in the femoral neck and total hip.     

Body Mass Index and Mortality among Korean Elderly in Rural Communities: Kangwha Cohort Study

BackgroundThe relationship between body mass index (BMI) and mortality may differ by ethnicity, but its exact nature remains unclear among Koreans. The study aim was to prospectively examine the association between BMI and mortality in Korean.Methods6166 residents (2636 men; 3530 women) of rural communities (Kangwha County, Republic of Korea) aged 55 and above were followed up for deaths from 1985–2008. The multivariable-adjusted hazard ratios were calculated using the Cox proportional hazards model.ResultsDuring the 23.8 years of follow-up (an average of 12.5 years in men and 15.7 years in women), 2174 men and 2372 women died. Men with BMI of 21.0–27.4 and women with BMI of 20.0–27.4 had a minimal risk for all-cause mortality. A lower BMI as well as a higher BMI increased the hazard ratio of death. For example, multivariable-adjusted hazard ratios associated with BMI below 16, and with BMI of 27.5 and above, were 2.4 (95% CI = 1.6–3.5) and 1.5 (95% CI = 1.1–1.9) respectively, in men, compared to those with BMI of 23.0–24.9. This reverse J-curve association was maintained among never smokers, and among people with no known chronic diseases. Higher BMI increased vascular mortality, while lower BMI increased deaths from vascular diseases, cancers, and, especially, respiratory diseases. Except for cancers, these associations were generally weaker in women than in men.ConclusionsA reverse J-curve association between BMI and all-cause mortality may exist. BMI of 21–27.4 (rather than the range suggested by WHO of 18.5–23 for Asians) may be considered a normal range with acceptable risk in Koreans aged 55 and above, and may be used as cut points for interventions. More concern should be given to people with BMI above and below a BMI range with acceptable risk. Further studies are needed to determine ethnicity-specific associations.     

Body Mass Index and Mortality in Korean Intensive Care Units: A Prospective Multicenter Cohort Study

Background

The level of body mass index (BMI) that is associated with the lowest mortality in critically ill patients in Asian populations is uncertain. We aimed to examine the association of BMI with hospital mortality in critically ill patients in Korea.

Methods

We conducted a prospective multicenter cohort study of 3,655 critically ill patients in 22 intensive care units (ICUs) in Korea. BMI was categorized into five groups: <18.5, 18.5 to 22.9, 23.0 to 24.9 (the reference category), 25.0 to 29.9, and ≥30.0 kg/m².

Results

The median BMI was 22.6 (IQR 20.3 to 25.1). The percentages of patients with BMI<18.5, 18.5 to 22.9, 23.0 to 24.9, 25.0 to 29.9, and ≥30.0 were 12, 42.3, 19.9, 22.4, and 3.3%, respectively. The Cox-proportional hazard ratios with exact partial likelihood to handle tied failures for hospital mortality comparing the BMI categories <18.5, 18.5 to 22.9, 25.0 to 29.9, and ≥30.0 with the reference category were 1.13 (0.88 to 1.44), 1.03 (0.84 to 1.26), 0.96 (0.76 to 1.22), and 0.68 (0.43 to 1.08), respectively, with a highly significant test for trend (p = 0.02).

Conclusions

A graded inverse association between BMI and hospital mortality with a strong significant trend was found in critically ill patients in Korea.     

Correlation of Body Mass Index and Age with Osteoporosis Probability in Patients with Primary Hyperparathyroidism

ObjectiveCurrently, there are limited markers to predict the osteoporosis probability in patients with primary hyperparathyroidism. We studied the relationship between various parameters and results of DXAs at various skeletal sites.MethodsRetrospective review of data for 218 patients with primary hyperparathyroidism was performed. Age, BMI, bone mineral density, serum total calcium, ionized calcium, intact parathyroid hormone, albumin, alkaline phosphatase, phosphate, 25-hydroxy vitamin D, 1,25-dihydroxy vitamin D, 24-hour urinary calcium levels and parathyroid tumor weight were analyzed. Two different statistical models- linear regression and multivariate logistic regression were performed.ResultsAt the lumbar spine, with the linear model, BMI (P < .001), alkaline phosphatase (P < .001), and ionized calcium (P < .001) significantly correlated with T scores; whereas with the logistic model, BMI was the only variable predicting osteoporosis probability.At the femoral neck, BMI (P < .022), 25-hydroxy vitamin D (P < .001), 1,25-dihydroxy vitamin D (P < .034) correlated with T scores; whereas both BMI (P < .029) and age (P < .051) were the significant variables that predicted osteoporosis.At the total hip, BMI (P < .001) and age (P < .001) correlated with T scores; whereas with the logistic model, only BMI (P < .016) predicted osteoporosis. At the forearm, a model could not be generated due to limited number.ConclusionIn patients with primary hyperparathyroidism, BMI strongly correlated with T scores and probability of osteoporosis.     

Perceived Stress and Coping Strategies in Relation to Body Mass Index: Cross-Sectional Study of 12,045 Japanese Men and Women

BackgroundAccumulated evidence suggests a weak positive relationship between psychosocial stress and body mass index (BMI), but little is known about stress coping strategies and BMI.ObjectiveWe aimed to examine if perceived stress and coping strategies are related to BMI, with any of their mutual interactions on BMI.MethodsThis cross-sectional study included 5,063 men and 6,982 women aged 40-69 years. A self-administered questionnaire ascertained perceived stress and 5 items of coping strategies (emotion expression, emotional support seeking, positive reappraisal, problem solving, and disengagement). Analyses were performed by gender with adjustment for age, socioeconomic status, and lifestyle factors.ResultsNo significant associations were detected between perceived stress and BMI in either men (P_trend = 0.09) or women (P_trend = 0.58). In men, however, ‘disengagement’ showed an inverse association with BMI (P_trend < 0.001), and ‘positive reappraisal’ and ‘problem solving’ revealed a positive association with BMI (P_trend = 0.04 and 0.007, respectively) even after controlling for perceived stress. A possible interaction between perceived stress and ‘disengagement’ on BMI was found in men (P_interaction = 0.027); the inverse association between ‘disengagement’ and BMI was more evident in higher levels of stress (β = −0.13, P_trend = 0.21 in low; β = −0.22, P_trend = 0.01 in medium; and β = −0.24, P_trend = 0.06 in high). In men, ‘disengagement’ was inversely associated with overweight/obesity (odds ratio 0.79, 95% confidential interval 0.67-0.95), and “positive reappraisal” was positively associated with it (1.25, 1.02-1.54).ConclusionsCoping strategies may have an important role in developing overweight/obesity, particularly in men.     

Body Mass Index and All-Cause Mortality in a Large Prospective Cohort of White and Black U.S. Adults

Remaining controversies on the association between body mass index (BMI) and mortality include the effects of smoking and prevalent disease on the association, whether overweight is associated with higher mortality rates, differences in associations by race and the optimal age at which BMI predicts mortality. To assess the relative risk (RR) of mortality by BMI in Whites and Blacks among subgroups defined by smoking, prevalent disease, and age, 891,572 White and 38,119 Black men and women provided height, weight and other information when enrolled in the Cancer Prevention Study II in 1982. Over 28 years of follow-up, there were 434,400 deaths in Whites and 18,702 deaths in Blacks. Cox proportional-hazards regression was used to estimate multivariable-adjusted relative risks (RR) and 95% confidence intervals (CI). Smoking and prevalent disease status significantly modified the BMI-mortality relationship in Whites and Blacks; higher BMI was most strongly associated with higher risk of mortality among never smokers without prevalent disease. All levels of overweight and obesity were associated with a statistically significantly higher risk of mortality compared to the reference category (BMI 22.5–24.9 kg/m²), except among Black women where risk was elevated but not statistically significant in the lower end of overweight. Although absolute mortality rates were higher in Blacks than Whites within each BMI category, relative risks (RRs) were similar between race groups for both men and women (p-heterogeneity by race  = 0.20 for men and 0.23 for women). BMI was most strongly associated with mortality when reported before age 70 years. Results from this study demonstrate for the first time that the BMI-mortality relationship differs for men and women who smoke or have prevalent disease compared to healthy never-smokers. These findings further support recommendations for maintaining a BMI between 20–25 kg/m² for optimal health and longevity.     

Higher Body Mass Index Increases the Risk for Biopsy-Mediated Detection of Prostate Cancer in Chinese Men

Objective

To investigate the relationship between body mass index (BMI) and prostate cancer (PCa) risk at biopsy in Chinese men.

Patients and Methods

We retrospectively reviewed the records of 1,807 consecutive men who underwent initial multicore (≥10) prostate biopsy under transrectal ultrasound guidance between Dec 2004 and Feb 2014. BMI was categorised based on the Asian classification of obesity as follows: <18.5 (underweight), 18.5–22.9 (normal weight), 23–24.9 (overweight), 25–29.9 (moderately obese), and ≥30 kg/m2 (severely obese). The odds ratios (OR) of each BMI category for risk of PCa and high-grade prostate cancer (HGPCa, Gleason score ≥4+3) detection were estimated in crude, age-adjusted and multivariate-adjusted models. Prevalence ratios and accuracies of PSA predicted PCa were also estimated across BMI groups.

Results

In total, PCa was detected by biopsy in 750 (45.4%) men, and HGPCa was detected in 419 (25.4%) men. Compared with men of normal weight, underweight men and obese men were older and had higher prostate specific antigen levels. The risk of overall PCa detection via biopsy presented an obvious U-shaped relationship with BMI in crude analysis. Overall, 50.0%, 37.4%, 45.6% 54.4% and 74.1% of the men in the underweight, normal weight, overweight, moderately obese and severely obese groups, respectively, were diagnosed with PCa via biopsy. In multivariate analysis, obesity was significantly correlated with a higher risk of PCa detection (OR = 1.17, 95%CI 1.10–1.25, P<0.001). However, higher BMI was not correlated with HGPCa detection (OR = 1.03, 95%CI 0.97–1.09, P = 0.29). There were no significant differences in the accuracy of using PSA to predict PCa or HGPCa detection across different BMI categories.

Conclusion

Obesity was associated with higher risk of PCa detection in the present Chinese biopsy population. No significant association was detected between obesity and HGPCa.     

Segregation Analysis of Body Mass Index in a Large Sample Selected for Obesity: The Swedish Obese Subjects Study

RICE, TREVA, c. DAVID SJÖSTRÖM, LOUIS PÉRUSSE, D. C. RAO, LARS SJÖSTRÖM, AND CLAUDE BOUCHARD. Segregation analysis of body mass index in a large sample selected for obesity: the Swedish Obese Subjects study. Obes Res. Objective: To investigate a major gene hypothesis for body mass index (BMI) in a large sample of probands (n = 2580, ages 37–57 years) who were selected for obesity (BMI≥34 kg/m² for males and ≥38 kg/m² for females), along with their spouses and first-degree relatives (n = 11,204 family members). The probands were recruited as part of an intervention trial assessing whether mortality and morbidity were improved after surgical intervention for obesity as part of the Swedish Obese Subjects (SOS) study. Methods and Procedures: The current analyses were based on BMI measures obtained before intervention. Segregation analysis was carried out using the mixed model implementation in PAP (Pedigree Analysis Package), which allowed for ascertainment correction and for genotype-dependent effects of covariates (sex and age) in both the major gene component and the multifactorial (i. e., polygenic and familial environment) component. Results: Both a major effect and a multifactorial effect were significant. The percentage of the total variance accounted for by the multifactorial effect was 17%-24% (increasing as a function of age), and by the major effect, 8%-34% (decreasing as a function of age). Although tests on the transmission probabilities (τS) were not compatible with Mendelian expectations of 1, 1/2, and 0, the equal τS model was rejected (i. e., the effect is transmitted in families) and the point estimates (0. 96,0. 60, and 0. 17) compared favorably to Mendelian expectations. The major effect was transmitted in a codominant fashion, consistent with a gene-environment interaction. Discussion: These results suggest both multifactorial and major effect etiologies for BMI in these families of extremely obese probands. Before 20 years of age, the major effect dominates the BMI expression, but after age 20, multifactorial effects account for the most variance. Although the major effect is transmitted in these families, the pattern does not appear to be consistent with a simple Mendelian trait. The possibility of additional major loci (i. e., epistasis) and gene by environment interactions may explain these findings.