Assessment of Triplet Fetal Growth by Using Cross-Sectional Analysis of the Birth Weight

Vignal, J; Daurès, Jean‐Pierre; Vergnes, C.; Giacalone, Pierre‐Ludovic; Boulot, P.

doi:10.1159/000020884

Cited by 2 publications

(1 citation statement)

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“…6 Few genetic studies incorporate such multiples, which also require additional zygosity information within the multiple sets. Furthermore, triplet and quadruplet sets are often reorganized as several separate twin pairs and analyzed accordingly, a practice that could violate the independence assumption across twin sets; this would result in biased estimates of genetic and environmental effects.…”

Section: Introductionmentioning

confidence: 99%

Genetic and environmental contributions to body mass index: comparative analysis of monozygotic twins, dizygotic twins and same-age unrelated siblings

et al. 2008

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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, age2, age3, height, height2, height3, 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.

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Section: Introductionmentioning

confidence: 99%