Assuntos
Córion/diagnóstico por imagem , Aconselhamento Genético/métodos , Testes Genéticos , Gêmeos Monozigóticos , Zigoto/diagnóstico por imagem , Feminino , Genótipo , Humanos , Recém-Nascido , Masculino , Pais , Acesso dos Pacientes aos Registros , Fenótipo , Valor Preditivo dos Testes , Gravidez , Relações entre Irmãos , UltrassonografiaRESUMO
BACKGROUND: Earlier studies have established that a substantial percentage of variance in obesity-related phenotypes is explained by genetic components. However, only one study has used both virtual twins (VTs) and biological twins and was able to simultaneously estimate additive genetic, non-additive genetic, shared environmental and unshared environmental components in body mass index (BMI). Our current goal was to re-estimate four components of variance in BMI, applying a more rigorous model to biological and virtual multiples with additional data. Virtual multiples share the same family environment, offering unique opportunities to estimate common environmental influence on phenotypes that cannot be separated from the non-additive genetic component using only biological multiples. METHODS: Data included 929 individuals from 164 monozygotic twin pairs, 156 dizygotic twin pairs, five triplet sets, one quadruplet set, 128 VT pairs, two virtual triplet sets and two virtual quadruplet sets. Virtual multiples consist of one biological child (or twins or triplets) plus one same-aged adoptee who are all raised together since infancy. We estimated the additive genetic, non-additive genetic, shared environmental and unshared random components in BMI using a linear mixed model. The analysis was adjusted for age, age(2), age(3), height, height(2), height(3), gender and race. RESULTS: Both non-additive genetic and common environmental contributions were significant in our model (P-values<0.0001). No significant additive genetic contribution was found. In all, 63.6% (95% confidence interval (CI) 51.8-75.3%) of the total variance of BMI was explained by a non-additive genetic component, 25.7% (95% CI 13.8-37.5%) by a common environmental component and the remaining 10.7% by an unshared component. CONCLUSION: Our results suggest that genetic components play an essential role in BMI and that common environmental factors such as diet or exercise also affect BMI. This conclusion is consistent with our earlier study using a smaller sample and shows the utility of virtual multiples for separating non-additive genetic variance from common environmental variance.
Assuntos
Índice de Massa Corporal , Simulação por Computador , Meio Ambiente , Modelos Genéticos , Gêmeos/genética , Envelhecimento/genética , Peso ao Nascer/genética , Tamanho Corporal/genética , Peso Corporal/genética , Criança , Dieta , Exercício Físico , Feminino , Humanos , Masculino , Grupo Associado , Quadrigêmeos/genética , Irmãos , Trigêmeos/genética , Gêmeos Dizigóticos/genética , Gêmeos Monozigóticos/genéticaRESUMO
OBJECTIVE: Application of a new investigative strategy to assess genetic and environmental influences on relative body weight. DESIGN: Covariance structure analysis of body mass index (BMI) using genetically informative samples. SUBJECTS: One-hundred and fourteen monozygotic (MZ) twin pairs (age 5.04-22.93 y), 81 dizygotic (DZ) twin pairs (age 6.05-16.52 y), and 98 virtual twin (VT) pairs, ie same-age unrelated siblings (3.68-54.75 y). MEASUREMENTS: Height, weight, BMI variously obtained by direct measurement and self-report. RESULTS: In contrast with most previous studies, significant common environmental influence on BMI was observed. CONCLUSION: Much past research may have underestimated common environmental effects on BMI because the designs lacked the power or ability to detect them.
Assuntos
Peso Corporal/genética , Meio Ambiente , Gêmeos , Adoção , Estatura , Índice de Massa Corporal , Humanos , Gêmeos Dizigóticos , Gêmeos MonozigóticosAssuntos
Transtornos da Comunicação/complicações , Transtornos da Comunicação/genética , Doenças em Gêmeos/genética , Esquizofrenia/complicações , Esquizofrenia/genética , Humanos , Estudos em Gêmeos como Assunto , Gêmeos Dizigóticos/genética , Gêmeos Dizigóticos/psicologia , Gêmeos Monozigóticos/genética , Gêmeos Monozigóticos/psicologiaRESUMO
OBJECTIVE: Our two previous reports showed that monozygotic (MZ) twins were significantly more concordant for both completed suicide and attempted suicide than dizygotic (DZ) twins. We wished to replicate the finding that MZ co-twins showed greater concordance for suicidal behavior. METHOD: We collected a new series of 28 twin pairs in which one twin had committed suicide. RESULTS: We found that 4 of the 13 MZ twin pairs were concordant for suicidal behavior compared with 0 of the 15 DZ twin pairs (P=0.035). CONCLUSIONS: These data confirm our previous reports that MZ co-twins show greater concordance for suicidal behavior than DZ co-twins, consistent with genetic influence.