We used Electrophoretic Mobility Shift Assay (EMSA) to investigate a potential functional role of both genotypes and methylation status in the regulatory region of NPSR1. We used two well characterized cohorts that offer unique opportunities to investigate genetics and epigenetics in relation to asthma phenotypes and environmental exposures; the BIOAIR study of severe asthma in adults [22] and the Swedish birth cohort BAMSE [23]. This evidence concerns the gene NPSR1 and asthma.