Lessons from a rare disease: IgG subclass and disease severity in alloimmune antenatal membranous nephropathy.

Fetomaternal alloimmunization against neutral endopeptidase (NEP) is a rare cause of antenatal membranous nephropathy, yet lessons from such cases continue to elucidate important pathophysiologic points. Vivarelli and colleagues describe two recent cases of this disease and demonstrate that despite a common genetic cause, differences in maternal anti-NEP IgG subclass modulate disease severity through such mechanisms as complement activation and enzyme inhibition.