The overall mean (each patient’s mean calculated individually and then averaged over all patients) of BTD enzyme activity in the profound deficiency group was 0.21 nmol/min/mL (range 0–0.50), and in the partial deficiency group 1.81 nmol/min/mL (range 0.90–2.96) (Figures 1E and S1A). This evidence concerns the gene BTD and hyperinsulinemic hypoglycemia, familial, 4.