Margaritte-Jeannin P, Budu-Aggrey A, Ege M, et al. - This study sought to distinguish genetic variants specifically associated with the co-morbidity of asthma-plus-eczema. Researchers performed a meta-analysis of four GWAS (genome-Wide Association Study) of the combined asthma-plus-eczema phenotype (total of 8,807 European-ancestry subjects of whom 1,208 subjects had both asthma and eczema). They also performed a meta-analysis of the homogeneity test of association according to disease status (“asthma-plus-eczema” versus the presence of only one disease “asthma only or eczema only”) to evaluate if the relationship with SNP(s) was specific to the co-morbidity. They applied a joint test by combining the two test statistics from the co-morbidity-SNP association and the phenotypic heterogeneity of SNP effect meta-analyses. The research demonstrates the importance of studying sub-phenotypes as co-morbidities to detect new susceptibility genes.