[MIM 201 750, 613 571]

Acronym for cytochrome P450 OxydoRreductase Deficiency

Rare. Autosomal recessive transmission of mutations of the POR gene (cytochrome P450 oxidoreductase) on7q11.2: this protein serves as the electron donor for several microsomal enzymes including CYP21A2 (21ß-hydroxylase), CYP17A1 (17α - hydroxylase and 17, 20-lyase), CYP19A1 (aromatase), and CYP51A1 (lanosterol 14α-demethylase). 

Depending on the mutation, different phenotypes can be produced:

-         in case of primarily skeletal abnormalities, one can observe the Antley-Bixler syndrome type 2 (see this topic): craniosynostosis with maxillary hypoplasia, arachnodactyly, conduction deafness, obstruction of the upper airway (choanal atresia), some joints contracture

-         in case of a dysfunction of the synthesis of cortisol, the picture is one of congenital adrenal hyperplasia (see this topic)

One can observe: 

• abnormalities of the genital organs:

-         boy: hypospadias, micropenis, delayed puberty, cryptorchidy

-        girl: hypertrophy of the clitoris, fusion of lips, delayed puberty, polycystic ovaries, urogenital sinus

• signs of maternal virilization during pregnancy if the fetus is a carrier of certain mutations

Anesthetic implications:

depending on the phenotype; even outside of the clinical picture of congenital adrenal hyperplasia, the functioning of the adrenal cortex may be altered: normal basal cortisol levels but reduced response to ACTH. To be kept in mind in case of unexplained hypotension.

References : 

-        Fukami M, Ogata T. 
Cytochrome P450 oxidoreductase deficiency: rare congenital disorder leading to skeletal malformations and steroidogenesis defects. 
Pediatrics International 2014 ; 56 : 805-8.

Updated: October 2018