Factors associated with degree of atopy in Latino children in a nationwide pediatric sample: the Genes-environments and Admixture in Latino Asthmatics (GALA II) study

Abstract

Background: Atopy varies by ethnicity, even within Latino groups. This variation might be due to environmental, sociocultural, or genetic factors.

Objective: We sought to examine risk factors for atopy within a nationwide study of US Latino children with and without asthma.

Methods: Aeroallergen skin test responses were analyzed in 1830 US Latino subjects. Key determinants of atopy included country/region of origin, generation in the United States, acculturation, genetic ancestry, and site to which subjects migrated. Serial multivariate zero-inflated negative binomial regressions stratified by asthma status examined the association of each key determinant variable with the number of positive skin test responses. In addition, the independent effect of each key variable was determined by including all key variables in the final models.

Results: In baseline analyses African ancestry was associated with 3 times (95% CI, 1.62-5.57) as many positive skin test responses in asthmatic participants and 3.26 times (95% CI, 1.02-10.39) as many positive skin test responses in control participants. Generation and recruitment site were also associated with atopy in crude models. In final models adjusted for key variables, asthmatic patients of Puerto Rican (exp[β] [95% CI], 1.31 [1.02-1.69]) and mixed (exp[β] [95% CI], 1.27 [1.03-1.56]) ethnicity had a greater probability of positive skin test responses compared with Mexican asthmatic patients. Ancestry associations were abrogated by recruitment site but not region of origin.

Conclusions: Puerto Rican ethnicity and mixed origin were associated with degree of atopy within US Latino children with asthma. African ancestry was not associated with degree of atopy after adjusting for recruitment site. Local environment variation, represented by site, was associated with degree of sensitization.

Keywords: GALA II; Genes-environments and Admixture in Latino Asthmatics; Latino; OR; Odds ratio; SES; SNP; Single nucleotide polymorphism; Socioeconomic status; ZINB; Zero-inflated negative binomial; aeroallergen; atopy; genetic ancestry; immigration; region of origin; skin test.

Figure 1. Positive skin prick tests by region of origin

This figure represents the proportion of participants with a positive skin test to allergens tested by region of origin. The proportions are represented on a scale in increments of 0.1 ranging from 0 (white) to 1.0 (black).

Figure 2. Global ancestry proportions of GALA II Latinos by origin and recruitment site

Diameter of pie charts represents size of group recruited at each site. Blue, yellow, and orange wedges represent African, European, and Native American ancestry respectively. Global ancestry proportions for population sizes less than 20 are not displayed on this map.

Figure 3. Ancestral proportions and recruitment site and case/control status

Each plot on these graphs represents a recruitment site. The Y – axis represents global estimates of individual Native American ancestral proportion and the X axis represents global estimates of individual African ancestral proportion. Asthmatic subjects are represented by square symbols and non-asthmatics are represented by circular symbols