Various degrees of GBA deficiency was observed among cell population: mean GBA residual activity in GD patients monocytes was of 28% compared to controls (19% and 30% in ERT treated and untreated patients, respectively) and of 39% in HSPCs (36% and 41% in ERT treated and untreated patients, respectively). The gene discussed is GBA1; the disease is hyperinsulinemic hypoglycemia, familial, 4.