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- Genetic regulation of body size and morphology in children: a twin study of 22 anthropometric traitsPublication . Silventoinen, Karri; Maia, José; Li, Weilong; Sund, Reijo; Gouveia, Élvio R.; Antunes, António; Marques, Gonçalo; Thomis, Martine; Jelenkovic, Aline; Kaprio, Jaakko; Freitas, Duarte Luís deAnthropometric measures show high heritability, and genetic correlations have been found between obesity related traits. However, we lack a comprehensive analysis of the genetic background of human body morphology using detailed anthropometric measures. METHODS: Height, weight, 7 skinfold thicknesses, 7 body circumferences and 4 body diameters (skeletal breaths) were measured in 214 pairs of twin children aged 3–18 years (87 monozygotic pairs) in the Autonomous Region of Madeira, Portugal. Factor analysis (Varimax rotation) was used to analyze the underlying structure of body physique. Genetic twin modeling was used to estimate genetic and environmental contributions to the variation and co-variation of the anthropometric traits. RESULTS: Together, two factors explained 80% of the variation of all 22 anthropometric traits in boys and 73% in girls. Obesity measures (body mass index, skinfold thickness measures, as well as waist and hip circumferences) and limb circumferences loaded most strongly on the first factor, whereas height and body diameters loaded especially on the second factor. These factors as well as all anthropometric measures showed high heritability (80% or more for most of the traits), whereas the rest of the variation was explained by environmental factors not shared by co-twins. Obesity measures showed high genetic correlations (0.75–0.98). Height showed the highest genetic correlations with body diameter measures (0.58–0.76). Correlations between environmental factors not shared by co-twins were weaker than the genetic correlations but still substantial. The correlation patterns were roughly similar in boys and girls. CONCLUSIONS: Our results show high genetic correlations underlying the human body physique, suggesting that there are sets of genes widely affecting anthropometric traits. Better knowledge of these genetic variants can help to understand the development of obesity and other features of the human physique.
- The genetic background of metabolic trait clusters in children and adolescentsPublication . Silventoinen, Karri; Gouveia, Élvio; Jelenkovic, Aline; Maia, José; Antunes, António M.; Carvalho, Miguel Â. A. Pinheiro de; Brehm, António M.; Thomis, Martine; Lefevre, Johan; Kaprio, Jaakko; Freitas, DuarteBackground: It is well known that the metabolic risk factors of cardiovascular diseases are correlated, but the background of this clustering in children is more poorly known than in adults. Thus, we studied the contribution of genetic and environmental factors to the clustering of metabolic traits in childhood and adolescence. Methods: Nine metabolic traits were measured in 214 complete twin pairs aged 3 to 18 years in the Autonomous Region of Madeira, Portugal, in 2007 and 2008. The variation of and covariations between the traits were decomposed into genetic and environmental components by using classical genetic twin modeling. Results: A model including additive genetic and environmental factors unique for each twin individual explained the variation of the metabolic factors well. Under this model, the heritability estimates varied from 0.47 (systolic blood pressure in children under 12 years of age) to 0.91 (HDL cholesterol in adolescents 12 years of age or older). The most systematic correlations were found between adiposity (body mass index and waist circumference) and blood lipids (HDL cholesterol, LDL cholesterol and triglycerides), as well as blood pressure. These correlations were mainly explained by common genetic factors. Conclusions: Our results suggest that obesity, in particular, is behind the clustering of metabolic factors in children and adolescents. Both general and abdominal obesity partly share the same genetic background as blood lipids and blood pressure. Obesity prevention already in childhood is important in reducing the risk of metabolic diseases in adulthood.