Polygenic risk and the development and course of asthma: an analysis of data from a four-decade longitudinal study.

BACKGROUND

Genome-wide association studies (GWAS) have discovered genetic variants that predispose individuals to asthma. To integrate these new discoveries with emerging models of asthma pathobiology, we aimed to test how genetic discoveries relate to developmental and biological characteristics of asthma.

METHODS

In this prospective longitudinal study, we investigated a multilocus profile of genetic risk derived from published GWAS of asthma case status. We then tested associations between this genetic risk score and developmental and biological characteristics of asthma in participants enrolled in a population-based long-running birth cohort, the Dunedin Multidisciplinary Health and Development Study (n=1037). We used data on asthma onset, asthma persistence, atopy, airway hyper-responsiveness, incompletely reversible airflow obstruction, and asthma-related school and work absenteeism and hospital admissions obtained during nine prospective assessments spanning the ages of 9 to 38 years. Analyses included cohort members of European descent from whom genetic data had been obtained.

FINDINGS

Of the 880 cohort members included in our analysis, those at higher genetic risk developed asthma earlier in life than did those with lower genetic risk (hazard ratio [HR] 1·12, 95% CI 1·01-1·26). Of cohort members with childhood-onset asthma, those with higher genetic risk were more likely to develop life-course-persistent asthma than were those with a lower genetic risk (relative risk [RR] 1·36, 95% CI 1·14-1·63). Participants with asthma at higher genetic risk more often had atopy (RR 1·07, 1·01-1·14), airway hyper-responsiveness (RR 1·16, 1·03-1·32), and incompletely reversible airflow obstruction (RR 1·28, 1·04-1·57) than did those with a lower genetic risk. They were also more likely to miss school or work (incident rate ratio 1·38, 1·02-1·86) and be admitted to hospital (HR 1·38, 1·07-1·79) because of asthma. Genotypic information about asthma risk was independent of and additive to information derived from cohort members' family histories of asthma.

INTERPRETATION

Our findings confirm that GWAS discoveries for asthma are associated with a childhood-onset phenotype. Genetic risk assessments might be able to predict which childhood-onset asthma cases remit and which become life-course-persistent, who might develop impaired lung function, and the burden of asthma in terms of missed school and work and hospital admissions, although these predictions are not sufficiently sensitive or specific to support immediate clinical translation.

FUNDING

US National Institute on Aging and UK Medical Research Council.