Pharmacogenomics is a branch of pharmacology concerned with using DNA and amino acid sequence data to inform drug development and testing. An important application of pharmacogenomics is correlating individual genetic variation with drug responses.

The global expression of immune response genes in infants after vaccination and their role in asthma and allergy is not clearly understood. Pharmacogenomics is ideally suited to study the involved cellular responses, since the expression of thousands of genes can be assessed simultaneously. Here, array technology was used to assess the expression kinetics of immune response genes with association to asthma and allergy in peripheral blood mononuclear cells (PBMC) of five healthy infants after vaccination with Infanrix-Polio+Hib. At 12h after in vitro re-stimulation of the PBMC with pertussis toxin (PT) antigen
14 immune response pathways, 33 allergy-related and 66 asthma-related genes were found activated.
Also
Cancer genes can be up-regulated and immunological disease genes.

http://www.ncbi.nlm.nih.gov/m/pubmed/18336961/