title: Clinical, genetic, and enzymatic characterization of P450 oxidoreductase deficiency in four patients.
abstract: BACKGROUND
  P450 oxidoreductase (POR) deficiency causes disordered steroidogenesis; severe mutations cause genital ambiguity in both sexes plus the Antley-Bixler skeletal malformation syndrome, whereas mild mutations can cause adult infertility.
  
  
  OBJECTIVE
  We describe four patients with POR deficiency and identify and characterize the activities of their mutations. A 46,XY male with micropenis and two 46,XX female infants with genital ambiguity presented with skeletal malformations, and a 46,XX adolescent presented with primary amenorrhea, elevated 17alpha-hydroxyprogesterone, and low sex steroids.
  
  
  METHODS
  The coding regions of the POR gene were sequenced, and the identified mutations were recreated in human POR cDNA expression vectors lacking 27 N-terminal residues. POR and human P450c17 were expressed in bacteria. POR activity was measured by four assays: reduction of cytochrome c, oxidation of reduced nicotinamide adenine dinucleotide phosphate, and support of the 17alpha-hydroxylase and 17,20 lyase activities of P450c17.
  
  
  RESULTS
  All four patients were compound heterozygotes for POR mutations, including five novel mutations: L577R, N185K, delE217, and frameshift mutations 1363delC and 697-698insGAAC. N185K and delE217 lacked measurable activity in the assays based on P450c17 but retained partial activity in the assays based on cytochrome c. As assessed by V(max)/Km, L577R supported 46% of 17alpha-hydroxylase activity but only 27% of 17,20 lyase activity. Computational modeling of these novel mutants revealed the structural basis for their reduced or absent activities.
  
  
  CONCLUSIONS
  These patients illustrate the broad clinical spectrum of POR deficiency, including amenorrhea and infertility as the sole manifestation. POR assays based on P450c17 correlate well with hormonal and clinical phenotypes.
authors.affiliation: Department of Pediatrics, University of California San Francisco, San Francisco, California 94143, USA.
authors.forename: Taninee
authors.initials: T
authors.lastname: Sahakitrungruang
authors.forename: Ningwu
authors.initials: N
authors.lastname: Huang
authors.forename: Meng Kian
authors.initials: MK
authors.lastname: Tee
authors.forename: Vishal
authors.initials: V
authors.lastname: Agrawal
authors.forename: William E
authors.initials: WE
authors.lastname: Russell
authors.forename: Patricia
authors.initials: P
authors.lastname: Crock
authors.forename: Nuala
authors.initials: N
authors.lastname: Murphy
authors.forename: Claude J
authors.initials: CJ
authors.lastname: Migeon
authors.forename: Walter L
authors.initials: WL
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000328:Adult; D001842:Bone and Bones / Q000002:abnormalities; D002384:Catalysis; D045304:Cytochromes c / Q000235:genetics; D004247:DNA / Q000235:genetics; D012734:Disorders of Sex Development / Q000235:genetics / Q000473:pathology; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D005822:Genetic Vectors; D005835:Genitalia / Q000002:abnormalities; D006728:Hormones / Q000097:blood; D006801:Humans; D007231:Infant, Newborn; D007246:Infertility / Q000235:genetics; D008297:Male; D009154:Mutation; D009249:NADP / Q000378:metabolism; D009251:NADPH-Ferrihemoprotein Reductase / Q000172:deficiency* / Q000235:genetics*; D011247:Pregnancy; D013254:Steroid 17-alpha-Hydroxylase / Q000235:genetics; D013577:Syndrome
chemical_list: D006728:Hormones; D009249:NADP; D045304:Cytochromes c; D004247:DNA; D013254:Steroid 17-alpha-Hydroxylase; D009251:NADPH-Ferrihemoprotein Reductase