Genetic Ancestry and Asthma and Rhinitis Occurrence in Hispanic Children: Findings from the Southern California Children's Health Study.
BACKGROUND
Asthma and rhinitis are common childhood health conditions. Being an understudied and rapidly growing population in the US, Hispanic children have a varying risk for these conditions that may result from sociocultural (including acculturative factors), exposure and genetic diversities. Hispanic populations have varying contributions from European, Amerindian and African ancestries. While previous literature separately reported associations between genetic ancestry and acculturation factors with asthma, whether Amerindian ancestry and acculturative factors have independent associations with development of early-life asthma and rhinitis in Hispanic children remains unknown. We hypothesized that genetic ancestry is an important determinant of early-life asthma and rhinitis occurrence in Hispanic children independent of sociodemographic, acculturation and environmental factors.


METHODS
Subjects were Hispanic children (5-7 years) who participated in the southern California Children's Health Study. Data from birth certificates and questionnaire provided information on acculturation, sociodemographic and environmental factors. Genetic ancestries (Amerindian, European, African and Asian) were estimated based on 233 ancestry informative markers. Asthma was defined by parental report of doctor-diagnosed asthma. Rhinitis was defined by parental report of a history of chronic sneezing or runny or blocked nose without a cold or flu. Sample sizes were 1,719 and 1,788 for investigating the role of genetic ancestry on asthma and rhinitis, respectively.


RESULTS
Children had major contributions from Amerindian and European ancestries. After accounting for potential confounders, per 25% increase in Amerindian ancestry was associated with 17.6% (95% confidence interval [CI]: 0.74-0.99) and 13.6% (95% CI: 0.79-0.98) lower odds of asthma and rhinitis, respectively. Acculturation was not associated with either outcome.


CONCLUSIONS
Earlier work documented that Hispanic children with significant contribution from African ancestry are at increased asthma risk; however, in Hispanic children who have little contribution from African ancestry, Amerindian ancestry was independently associated with lower odds for development of early-childhood asthma and rhinitis.
Department of Preventive Medicine, University of Southern California, Keck School of-Medicine, Los Angeles, California, United States of America; Department of Psychiatry, Kern Medical Center, Bakersfield, California, United States of America.
Muhammad T
MT
Salam
US Department of Veterans Affairs, Center for Health Care Evaluation, Palo Alto, California, United States of America.
Tigran
T
Avoundjian
Los Angeles County Department of Public Health, Acute Communicable Disease Control Program, Los Angeles, California, United States of America.
Wendy M
WM
Knight
Department of Preventive Medicine, University of Southern California, Keck School of-Medicine, Los Angeles, California, United States of America.
Frank D
FD
Gilliland
D001249:Asthma / Q000453:epidemiology* / Q000235:genetics*; D002140:California / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D006630:Hispanic or Latino; D006801:Humans; D008297:Male; D062486:Public Health Surveillance; D012220:Rhinitis / Q000453:epidemiology* / Q000235:genetics*; D012307:Risk Factors