Aim: To carry out a genome-wide association study that takes into account not just lifetime asthma status but also the presence of hayfever.

Hypotheses: The power of asthma genome-wide association studies (GWAS) can be improved -- and so new susceptibility loci can be identified -- by defining cases and controls based on diagnostic criteria that are more refined than a simple doctor diagnosis of asthma. We hypothesise that the presence of hayfever in addition to asthma defines a subgroup of asthma patients that will help map new loci for allergic disease.

Independent variable: Individual genotyped or imputed SNPs located in the autosomes or X-chromosome, coded as allelic dosage.

Dependent variable: Binary phenotype (ie case-control status) with affected individuals defined as those individuals who reported in any of the available ALSPAC surveys (7.5 and 14 years) to have been diagnosed by a doctor with asthma *AND* reported in any of the available surveys (11 and 14 years) to have hayfever. So lifetime self-reported asthmatics with hayfever. Unaffected individuals are defined as those individuals who never reported in any survey to have asthma or hayfever.

Confounding variable: None.

Analysis plan: Perform association analysis of SNP dosage after applying standard QC filters (eg. MAFgreater than 1%, HW P-value greater than 10-6, call rate greater than 95%, imputation info/r2 greater than =0.3) and excluding samples of non-European ancestry. Analyse males and females separately and include SNPs on the autosomes and the X-chromosome.