In contrast, Z α1-antitrypsin bound to mAb4B12 retained almost two thirds of its inhibitory activity against neutrophil elastase in vitro, supporting the use of mAb4B12 (as whole antibody or intrabody) as a research tool in α1-antitrypsin deficiency. The gene discussed is ELANE; the disease is hyperinsulinemic hypoglycemia, familial, 4.