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Sibling similarity in development of covariation among physical traits in early childhood
Insights
Sibling similarity reveals distinct genetic factors influencing infant growth. Early development (0-2 months) and later childhood stages show separate patterns in body weight, length, and head circumference.
Area of Science:
- Human genetics
- Developmental biology
- Anthropometry
Background:
- Sibling similarity studies are crucial for understanding genetic and environmental influences on human development.
- Body size traits like weight, length, and head circumference are key indicators of infant growth.
- Previous research has explored various factors affecting anthropometric measurements, but patterns of covariation over time require further elucidation.
Purpose of the Study:
- To investigate sibling similarity in the developmental covariation of body weight, body length, and head circumference in infants.
- To examine the influence of parental and familial factors on these anthropometric traits.
- To identify underlying genetic subsystems influencing early and later stages of human ontogeny.
Main Methods:
- Sibling similarity analysis was used to estimate phenotypic and genetic correlations.
- Multiple regression with dummy variables assessed the impact of parental and familial factors.
- Principal component analysis was applied to age-specific anthropometric data matrices (birth to 2 years).
Main Results:
- Parental geographic origin, profession, age, residence, and family size did not significantly affect anthropometric traits.
- Both phenotypic and genetic correlation analyses revealed similar patterns over age groups.
- One primary factor correlated with early growth (0-3 months), while three other factors correlated with later growth stages for all traits.
Conclusions:
- Human growth exhibits distinct developmental trajectories influenced by separate genetic subsystems.
- The first genetic subsystem appears to govern early postnatal development (0-3 months).
- A second genetic subsystem likely influences later phases of child development, impacting body size traits.
Abstract:
We studied the sibling similarity in development of covariation among body size characters (body weight (W), body length (S) and head circumference (HC) in Tel Aviv infants from birth up to 2 years of age. We investigated the effects of parental geographic origin, profession, age, current residence, and of family size. Multiple regression analysis with "dummy" procedure established that none of these variables had any significant effect on the aforementioned anthropometric traits. The matrices of phenotypic and genetic correlations, based on sibling similarity data, among age-specific W, S, and HC (measured for 12 different ages) were subjected to principal component analysis in order to elucidate patterns over the age groups. The patterns of both analyses, phenotypic and genetic, were quite similar: one factor in each (first genetic and second phenotypic) had a high positive correlation with early, first 2-3 months of life, W, S, and HC. Three other extracted factors correlated strongly, each with late W, S, and HC, respectively. The results of additional principal component analyses of age-specific W, S, and HC matrices separately, indicate the possibility of existence of two genetic subsystems, the first determining early postnatal stages of human ontogeny, and the second, later phases of child development.