title: Clinical, genetic, and functional characterization of four patients carrying partial loss-of-function mutations in the steroidogenic acute regulatory protein (StAR).
abstract: BACKGROUND
  Nonclassic congenital lipoid adrenal hyperplasia (lipoid CAH) is a recently recognized disorder caused by mutations in the steroidogenic acute regulatory protein (StAR) that retain partial function. Affected individuals can present with a phenotype of late onset adrenal insufficiency with only mild or minimally disordered sexual development.
  
  
  OBJECTIVE
  The aim was to delineate the clinical spectrum of StAR mutations and correlate phenotype with StAR activity.
  
  
  METHODS
  Four patients had nonclassic/atypical lipoid CAH. Adrenal insufficiency was manifested at birth in two patients and at 11 months and 4 yr in the other two. Three were 46,XY with underdeveloped genitalia.
  
  
  METHODS
  The StAR gene was sequenced, mutations were recreated in expression vectors, and StAR activity was measured as pregnenolone production in COS-1 cells cotransfected with the cholesterol side-chain cleavage system. StAR mutants were expressed as N-62 StAR in bacteria, and purified proteins were tested for activity with isolated steroidogenic mitochondria and for cholesterol-binding capacity.
  
  
  RESULTS
  DNA sequencing identified mutations on all alleles. Missense mutations were R188C, G221D, L260P, and F267S; we also tested R192C described by others. The respective activities of R188C, R192C, G221D, L260P, and F267S were 8.0, 39.4, 2.4, 3.1, and 6.1% of wild-type in transfected cells, and 12.8, 54.8, 6.3, 1.8, and 9.5% with isolated mitochondria. Cholesterol binding capacities of R188C, R192C, G221D, L260P, and F267S were 6.7, 55.3, 10.2, 4.6, and 20.9%. These data are correlated to the three-dimensional structure of StAR.
  
  
  CONCLUSIONS
  There is a broad clinical spectrum of StAR mutations; StAR activities in vitro correlate well with clinical phenotypes.
authors.affiliation: Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, 10330 Bangkok, Thailand. [corrected].
authors.forename: Taninee
authors.initials: T
authors.lastname: Sahakitrungruang
authors.forename: Raymond E
authors.initials: RE
authors.lastname: Soccio
authors.forename: Mariarosaria
authors.initials: M
authors.lastname: Lang-Muritano
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Walker
authors.forename: John C
authors.initials: JC
authors.lastname: Achermann
authors.forename: Walter L
authors.initials: WL
authors.lastname: Miller
mesh_terms: D000293:Adolescent; D000312:Adrenal Hyperplasia, Congenital / Q000235:genetics* / Q000378:metabolism; D000309:Adrenal Insufficiency / Q000235:genetics / Q000378:metabolism; D000328:Adult; D002675:Child, Preschool; D002784:Cholesterol / Q000235:genetics / Q000378:metabolism; D005260:Female; D056726:Genetic Association Studies; D006801:Humans; D007223:Infant; D008297:Male; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D000098682:Steroidogenic Acute Regulatory Protein
chemical_list: D010750:Phosphoproteins; D000098682:Steroidogenic Acute Regulatory Protein; D002784:Cholesterol
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