Unraveling shared genetics across asthma subtypes and 81 asthma-related traits.

Vernet, Raphaël; Linhard, Christophe; Estermann, Anja; Suzuki, Yuka; Demenais, Florence; Aschard, Hugues; Julienne, Hanna; Bouzigon, Emmanuelle · J Allergy Clin Immunol · 2025

basic_science · Level V

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Abstract

Asthma presents clinical and biological heterogeneity. We sought to better understand asthma heterogeneity by investigating the shared genetics between various asthma subtypes and a large number of biological and physiologic traits involved in asthma pathophysiology. We built a harmonized comprehensive database of 254 full genome-wide association study summary statistics datasets on asthma, asthma subtypes and 81 asthma-related traits (blood cells and molecular, anthropometric, and lung function traits). We enriched this database by performing meta-analyses for asthma-related traits reported in ≥2 studies. Then we identified shared genome-wide significant loci and estimated genetic overlaps and correlations (r<sub>g</sub>) between asthma subtypes and asthma-related traits by MiXeR software and linkage disequilibrium score regression. Overall, asthma-associated loci were more pleiotropic than non-asthma-associated loci (median of shared traits, 4 vs 1, P = 1.3 × 10<sup>-36</sup>). Childhood-onset and moderate-to-severe asthma had higher SNP heritability (h<sup>2</sup><sub>SNP</sub> ± standard error [SE], 0.27 ± 0.004 and 0.16 ± 0.02, respectively) than adult-onset asthma (0.08 ± 0.002) and asthma ever (0.06 ± 0.001). All asthma subtypes showed significant r<sub>g</sub> with eosinophils and IgE levels (0.24 ≤ r<sub>g</sub> ≤ 0.40, 5.1 × 10<sup>-14</sup> ≤ P ≤ .04), with childhood-onset asthma sharing 94% of "causal" variants with IgE, whereas other asthma subtypes shared <60%. Adult-onset asthma showed significant r<sub>g</sub> and shared a substantial amount of causal variants with adult body mass index (r<sub>g</sub> = 0.26, P < .007; shared variants, 84%) and forced expiratory volume in 1 second (r<sub>g</sub> = -0.36, P < 7.7 × 10<sup>-10</sup>; shared variants, 95%). Finally, moderate-to-severe asthma was characterized by a significant r<sub>g</sub> with hepatocyte growth factor levels (r<sub>g</sub> = 0.38, P = 6 × 10<sup>-4</sup>), a potential biomarker of lung injury. Common and specific genetic architectures underlie different asthma subtypes and can help us understand the pathophysiologic mechanisms underlying asthma heterogeneity.

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