While 85% of asthmatic patients have rhinitis, only 20-30% with rhinitis have asthma. Together with atopic dermatitis (AD), rhinitis and asthma form a triad that tend to co-exist in patients (multimorbidity). This co-existence raises the possibility of genetic mechanism. Authors reported the first analysis of multimorbidity molecular signatures. Authors used RNA sequencing and transcriptomics, which studies the complete RNA transcripts set coded by the genome. A total of 1233 participants were included. Authors compared asthma, AD and rhinitis as single or combined diseases with no disease. A new 32 genes were differentially expressed in allergic diseases. Additionally, in patients with multimorbidity, eight genes were over-expressed. Patients with rhinitis, as a single disease, showed an over-expression of 27 genes. This was in contrast to AD and asthma, where no specific genes were identified. Moreover, IL5/JAK/STAT and IL33/ST2/IRAK/TRAF were identified as key signalling pathways in patients with multimorbidity. The new genetic signature of asthma, rhinitis and AD, alone and in combination, can pave the way for new diagnostic and therapeutic interventions. This paper contributes to our knowledge of allergic diseases. It also highlights the importance of genetics in our future management of allergy.