Pooled Sequencing of Candidate Genes Implicates Rare Variants in the Development of Asthma Following Severe RSV Bronchiolitis in Infancy.

Dara G Torgerson,Ryan D Hernandez,Jie Zheng,Kenneth B Schechtman,Tusar Giri,Leonard B Bacharier,Toni Schweiger,Huiqing Yin-Declue,Adrienne G Randolph,Scott Huntsman,Max A Seibold,Todd E Druley,Andrew L Young,Geneline D Sajol,Mario Castro

doi:10.1371/journal.pone.0142649

Abstract

Severe infection with respiratory syncytial virus (RSV) during infancy is strongly associated with the development of asthma. To identify genetic variation that contributes to asthma following severe RSV bronchiolitis during infancy, we sequenced the coding exons of 131 asthma candidate genes in 182 European and African American children with severe RSV bronchiolitis in infancy using anonymous pools for variant discovery, and then directly genotyped a set of 190 nonsynonymous variants. Association testing was performed for physician-diagnosed asthma before the 7th birthday (asthma) using genotypes from 6,500 individuals from the Exome Sequencing Project (ESP) as controls to gain statistical power. In addition, among patients with severe RSV bronchiolitis during infancy, we examined genetic associations with asthma, active asthma, persistent wheeze, and bronchial hyperreactivity (methacholine PC20) at age 6 years. We identified four rare nonsynonymous variants that were significantly associated with asthma following severe RSV bronchiolitis, including single variants in ADRB2, FLG and NCAM1 in European Americans (p = 4.6x10-4, 1.9x10-13 and 5.0x10-5, respectively), and NOS1 in African Americans (p = 2.3x10-11). One of the variants was a highly functional nonsynonymous variant in ADRB2 (rs1800888), which was also nominally associated with asthma (p = 0.027) and active asthma (p = 0.013) among European Americans with severe RSV bronchiolitis without including the ESP. Our results suggest that rare nonsynonymous variants contribute to the development of asthma following severe RSV bronchiolitis in infancy, notably in ADRB2. Additional studies are required to explore the role of rare variants in the etiology of asthma and asthma-related traits following severe RSV bronchiolitis.

Highlights

Asthma is a complex disease caused by both genetic and environmental factors, and the interactions between them.[1]
We identified four rare nonsynonymous variants that were significantly associated with asthma following severe respiratory syncytial virus (RSV) bronchiolitis, including single variants in ADRB2, FLG and NCAM1 in European Americans (p = 4.6x10-4, 1.9x10-13 and 5.0x10-5, respectively), and NOS1 in African Americans (p = 2.3x10-11)
We identified over 700 nonsynonymous variants by sequencing the coding exons of 131 asthma-associated genes in 182 individuals who experienced severe RSV bronchiolitis in infancy

Summary

Introduction

Asthma is a complex disease caused by both genetic and environmental factors, and the interactions between them.[1]. More than 100 genes have been associated with asthma and asthma-related traits, there is marked variability in replication attempts in independent studies.[9] This may in part be due to low statistical power from small samples, inadequate control for multiple comparisons, heterogeneity in environmental exposures and outcome measurement, and differences in study design. Genome-wide association (GWA) studies have focused on the search for common genetic risk variants (allele frequencies > 5%) that influence complex diseases.[10] the risk alleles identified through these studies have explained only a small proportion of the heritability of this complex disease.[11]

Methods

Results

Conclusion