Decay‐accelerating factor (DAF), a GPI‐anchored regulator, is not expressed in the labyrinthine placenta until after ~10.5 dpc.13 Other C3 regulators of complement such as FH are present in maternal blood but they are unable to compensate for Crry deficiency. The gene discussed is C3; the disease is hyperinsulinemic hypoglycemia, familial, 4.