At that time, initial laboratory investigations revealed mild hypochromic microcytic anemia (Hb, 11.4 g/dL), marked eosinophilia (990/mm3), no evidence of inflammatory syndrome, normal coagulation profile, and elevated total IgE (104.3 IU/mL).Nasal eosinophils were absent, and polymerase chain reaction (PCR) tests for respiratory syncytial virus (RSV) and Mycoplasma pneumoniae were negative. The gene discussed is GSTM1; the disease is Increased total eosinophil count.