This invention relates to the diagnosis, treatment and methods for discovery of new therapeutics for atopic asthma and related disorders based on variants of Asthma Associated Factor 2. One embodiment of the invention is a variant of AAF2 wherein codon 173 is deleted resulting in the loss of glutamine 173 from the mature protein precursor. This single amino acid deletion results in a non-functional AAF2 protein and therefore the presence of this phenotype should be associated with less evidence of atopic asthma. Correspondingly, the lack of susceptibility to an asthmatic, atopic phenotype is characterized by the loss of glutamine at codon 171 The invention includes isolated DNA molecules which are variants of the wild type sequence as well as the proteins encoded by such DNA and the use of such DNA molecules and expressed protein in the diagnosis and treatment of atopic asthma.