- PLoS One
- v.8(7); 2013
- PMC3700929
PLoS One. 2013; 8(7): e68473.
Published online 2013 July 3. doi: 10.1371/journal.pone.0068473
PMCID: PMC3700929
A Twin Study of Early-Childhood Asthma in Puerto Ricans
Supinda Bunyavanich,#1,2,3,4,5,* Judy L. Silberg,#6 Jessica Lasky-Su,4,5 Nathan A. Gillespie,7,8 Nancy E. Lange,4,5Glorisa Canino,9 and Juan C. Celedόn10,11,12
Andrew Dewan, Editor
Abstract
Background
The relative contributions of genetics and environment to asthma in Hispanics or to asthma in children younger than 3 years are not well understood.
Objective
To examine the relative contributions of genetics and environment to early-childhood asthma by performing a longitudinal twin study of asthma in Puerto Rican children ≤3 years old.
Methods
678 twin infants from the Puerto Rico Neo-Natal Twin Registry were assessed for asthma at age 1 year, with follow-up data obtained for 624 twins at age 3 years. Zygosity was determined by DNA microsatellite profiling. Structural equation modeling was performed for three phenotypes at ages 1 and 3 years: physician-diagnosed asthma, asthma medication use in the past year, and ≥1 hospitalization for asthma in the past year. Models were additionally adjusted for early-life environmental tobacco smoke exposure, sex, and age.
Results
The prevalences of physician-diagnosed asthma, asthma medication use, and hospitalization for asthma were 11.6%, 10.8%, 4.9% at age 1 year, and 34.1%, 40.1%, and 8.5% at 3 years, respectively. Shared environmental effects contributed to the majority of variance in susceptibility to physician-diagnosed asthma and asthma medication use in the first year of life (84%–86%), while genetic effects drove variance in all phenotypes (45%–65%) at age 3 years. Early-life environmental tobacco smoke, sex, and age contributed to variance in susceptibility.
Conclusion
Our longitudinal study in Puerto Rican twins demonstrates a changing contribution of shared environmental effects to liability for physician-diagnosed asthma and asthma medication use between ages 1 and 3 years. Early-life environmental tobacco smoke reduction could markedly reduce asthma morbidity in young Puerto Rican children.
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