The fC1INH LC-MS/MS assay from DBS was tested in 30 samples from patients (11 male and 19 female patients) with previously diagnosed recurrent angioedema due to C1INH deficiency and 100 samples (male/female ratio ∼50%/50%) from healthy subjects (Table I). The gene discussed is SERPING1; the disease is hyperinsulinemic hypoglycemia, familial, 4.