A large-scale, consortium-based genomewide association study of asthma.

Area of Science:

• Genetics and Immunology
• Respiratory Medicine

Background:

• Asthma susceptibility is a complex interplay of genetic and environmental factors.
• Identifying genetic risk factors can aid in classifying asthma subtypes and understanding disease mechanisms.
• Investigating intermediate phenotypes like serum IgE levels may reveal causal links to asthma.

Purpose of the Study:

• To conduct a genomewide association study (GWAS) to identify genetic variants associated with asthma.
• To explore the association of genetic factors with different asthma subtypes, including childhood-onset, later-onset, severe, and occupational asthma.
• To determine the relationship between genetic loci, asthma, and total serum IgE levels.

Main Methods:

• A large-scale GWAS involving 10,365 asthma patients and 16,110 controls, matched for ancestry.
• Random-effects pooled analysis was employed to test for genetic associations.
• Subgroup analyses were performed for various asthma phenotypes.

Main Results:

• Significant genomewide associations were found for single-nucleotide polymorphisms (SNPs) implicating genes such as IL1RL1/IL18R1, HLA-DQ, IL33, SMAD3, and IL2RB.
• A specific association with the ORMDL3/GSDMB locus on chromosome 17q21 was observed exclusively in childhood-onset asthma.
• Only HLA-DR showed a significant association with total serum IgE concentration; loci strongly linked to IgE were not associated with asthma.

Conclusions:

• Asthma exhibits genetic heterogeneity, with common alleles contributing to disease risk across different ages.
• The identified genes suggest pathways involving epithelial damage signaling to the adaptive immune system and airway inflammation.
• Specific genetic variants at the ORMDL3/GSDMB locus are linked solely to childhood-onset asthma, and elevated total serum IgE levels play a minor role in asthma development.