Factors that increase the risk or severity of hypersensitivity reactions in patients given iron infusions include a previous reaction to IV iron, fast iron infusion rate, history of other drug allergy or allergies, severe asthma or eczema, mastocytosis, severe respiratory or cardiac disease, old age, treatment with beta-blockers and/or ACE inhibitors, pregnancy (first trimester), and systemic inflammatory disease (e.g., rheumatoid arthritis and systemic lupus erythematosus) [3]. The gene discussed is ACE; the disease is allergic disease.