Several studies reported that deletions in the GSTT1 (GSTT1 −/−) and GSTM1 (GSTM1 −/−), also called null genotypes, are linked with the loss of enzyme activity of the GST gene, increasing the risk for oxidative stress associated with multifactorial diseases including cardiovascular and respiratory diseases [13]. This evidence concerns the gene GSTM1 and respiratory system disorder.