Keeping in mind reports on a group of patients in the Polish population who are genetically predisposed to symptomatic hypercalcemia (carrying CYP24A1 or SLC34A1 gene mutations, resulting in decreased catabolism or excessive formation of an active form of vitamin D, respectively) (26), the Expert Panel suggests to consider a directed medical history investigation, anteceding vitamin D supplementation with vitamin D doses higher than recommended for the general population, in order to minimize the risk of adverse events in a individuals with vitamin D hypersensitivity. The gene discussed is SLC34A1; the disease is Hypercalcemia.