SEMA3D and asthma: McGeachie et al. performed a GWAS in three cohorts of patients ranging from paediatric to adult age and identified two regulatory SNPs within cathenin alpha 3 gene (CTNNA3) and semaphorin 3D gene (SEMA3D) that are associated with asthma exacerbations, defined as the need of a 5-day course of oral corticosteroid treatment.