POR knockout mice are embryonic lethal,[11] probably due to lack of electron transport to extrahepatic P450 enzymes since liver-specific knockout of POR yields phenotypically and reproductively normal mice that accumulate hepatic lipids and have remarkably diminished capacity of hepatic drug metabolism.

In yeast, POR affects the ferrireductase activity, probably transferring electrons to the flavocytochrome ferric reductase.

[16] The index patient was a newborn 46,XX Japanese girl with craniosynostosis, hypertelorism, mid-face hypoplasia, radiohumeral synostosis, arachnodactyly and disordered steroidogenesis.

Some of the POR patients were born to mothers who became virilized during pregnancy, suggesting deficient placental aromatization of fetal androgens due to a lesion in microsomal aromatase resulting in low estrogen production, which was later confirmed by lower aromatase activities caused by POR mutations.

Cells with this genetic deletion show reduced transcription of POR, it seems, due to the loss of a cis-regulatory element that alters expression of this gene.

[30] Some persons with Williams syndrome show characteristics of POR deficiency, including radioulnar synostosis and other skeletal abnormalities.

[33] A similar increase in testosterone has been observed in a mouse model that has globally decreased POR expression.