No abstract

Samoans are experiencing some of the highest prevalences of obesity and associated health conditions in the world. Sustainable interventions are needed to prevent further increases in obesity. This study describes the cross-sectional association between farm work and adiposity among 754 adults residing in American Samoa in 2002 and 957 adults residing in Samoa in 2003. Adiposity was measured by body mass index (BMI) and percent body fat (% BF), based on bioelectrical impedance. Regression models adjusted for the effects of age, education, occupation (in women), and material lifestyle (MLS), and the clustering within households due to the family design of the parent study. After controlling for these variables, participation in farm work was associated with a significantly lower BMI and % BF in men of all ages residing in American Samoa, women >or=45 years residing in American Samoa, and women 18-44 years residing in Samoa, and a significantly lower BMI in men 18-44 years residing in Samoa. These results suggest that farm work plays an important role in regulating body size and fatness of adult Samoans and may be ideal for interventions in the Samoan archipelago.

Objective: To detect quantitative trait loci influencing adiposity-related phenotypes assessed by body mass index (BMI), abdominal circumference (ABDCIR), percent body fat (%BFAT) and fasting serum leptin and adiponectin using a whole genome linkage scan of families from American Samoa. Design: Family-based linkage analysis, the probands and family members were unselected for obesity. Subjects: A total of 583 phenotyped American Samoan adults, of which 578 were genotyped in 34 pedigrees. Measurements: A total of 377 autosomal and 18 X chromosome microsatellite markers were typed at an approximate average spacing of 10 cM spanning the genome. Multipoint LOD (logarithm of the odds) scores were calculated using variancecomponents approaches and SOLAR/LOKI software. The covariates simultaneously evaluated were age, sex, education, farm work and cigarette smoking, with a significance level of 0.1. Due to the stochastic nature of LOKI, we report the average of maximum LOD scores from 10 runs. Results: Significant linkage to leptin was found at 6q32.2 with LOD of 3.83. Suggestive linkage to leptin was found at 16q21:LOD ¼ 2.98, 1q42.2:LOD ¼ 1.97, 5q11.2:LOD ¼ 2.08, 12q24.23:LOD ¼ 2.00, 19p13.3:LOD ¼ 2.05; adiponectin was linked to 13q33.1-q22.1:LOD ¼ 2.41; %BFAT was linked to 16q12.2-q21, LOD ¼ 2.24; ABDCIR was linked to 16q23.1:LOD ¼ 1.95; %BFAT-adjusted leptin to 14q12, LOD ¼ 2.01; %BFAT-adjusted ABDCIR to 1q31.1, LOD ¼ 2.36, to 3q27.3-q28, LOD ¼ 2.10 and to 12p12.3, LOD ¼ 2.04. Conclusion: We found strong evidence for a major locus on 6q23.2 influencing serum leptin levels in American Samoans. The 16q21 region appears to harbor a susceptibility locus that has significant pleiotrophic effects on phenotypes BMI, %BFAT, leptin and ABDCIR as shown by bivariate linkage analyses. Several other loci of varying significance were detected across the genome.