There are several affecting factors for anaphylactic reaction by iodinated CM such as particularly allergy (arising from consuming sea foods or drugs), previous adverse reactions, history of asthma or bronchospasm, history of allergy, cardiac disease, dehydration, haematological and metabolic conditions (sickle cell anaemia, patients with thrombotic tendency), renal disease, neonates, old patients, anxiety and apprehension medications (β-blockers, interleukin-2 (IL-2), aspirin, NSAIDs) [33]. This evidence concerns the gene IL2 and sickle cell disease.