 A unique feature of this disease is the maternal inheritance effect, when a fetus inherits a mutated copy of the RBP4 gene from its mother, but not from its father.The physiologic basis lies in pregnancy whereby the mutated gene product, retinol binding protein (RBP), has negative effects in transferring vitamin A from maternal liver storage sites to the placenta, and then again on the fetal circulation side when delivering vitamin A from the placenta to developing fetal tissues, most notably the developing eye.This 'double whammy' effect does not exist when the mutant RBP4 gene is inherited from the father.