Acquired FXI inhibitors in patients without congenital FXI deficiency have been associated with systemic lupus erythematosus (SLE) [8, 11], hematopoietic malignancies [5, 6, 9], solid cancer [7], inflammatory bowel disease [7], chlorpromazine-treatment [4], and pelvic surgery [10]. Here, F11 is linked to hyperinsulinemic hypoglycemia, familial, 4.