 Thirty subjects will be screened to identify 20 subjects with severe persistent asthma. The following data andor samples will then be obtained within three weeks of the clinical assessment: 1 the percentages of LDG will be quantified by flow cytometry; 2 a blood sample will be collected into a PAXgene Blood tube and stored until shipped to Genentech for gene profiling analysis; and 3 a serum sample will be collected for measurement of total immunoglobulin E IgE and for future confirmation of potential biomarkers identified in the gene profiling analyses. 