Polymorphisms of CYP genes (CYP1A1, CYP1A2, CYP1B1, CYP2B6, CYP2C9, CYP3A4, CYP2D6 and CYP2C19) and the PON1 gene have been actively studied in connection with the development of a wide range of oncological, cardiovascular, and allergic diseases, and also in populations professionally exposed to pesticides [13,41,42,43,44,45]. This evidence concerns the gene CYP3A4 and allergic disease.