title: 46,XY karyotype in a female phenotype fetus: a challenging diagnosis.
abstract: BACKGROUND
  The growing use of prenatal investigations allows an early detection of several inborn disorders, including disorders of sexual development. The management of these conditions is an arising problem.
  
  
  METHODS
  46,XY karyotype and female phenotype were detected in a fetus; 5α-reductase and androgen receptor gene analysis on chorionic villi revealed no relevant mutation. The newborn was assigned to female sex. The diagnosis of 17β-hydroxysteroid dehydrogenase-3 β-OL deficiency was reached at four months of age, by means of a low testosterone/Δ 4-androstenedione ratio after HCG test and HSD17B3 gene analysis.
  
  
  CONCLUSIONS
  A 46,XY fetus with female external genitalia suggests different conditions, some very rare. Specific genetic investigations should be performed prenatally when possible. A complete evaluation is mandatory after delivery to reach a correct diagnosis.
authors.affiliation: Department of Pediatrics, Endocrine Unit, Scientific Institute San Raffaele, Milan, Italy. russo.gianni26@gmail.com
authors.forename: Gianni
authors.initials: G
authors.lastname: Russo
authors.forename: Alessandra
authors.initials: A
authors.lastname: di Lascio
authors.forename: Matilde
authors.initials: M
authors.lastname: Ferrario
authors.forename: Silvia
authors.initials: S
authors.lastname: Meroni
authors.forename: Olaf
authors.initials: O
authors.lastname: Hiort
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Chiumello
mesh_terms: D015067:17-Hydroxysteroid Dehydrogenases / Q000172:deficiency*; D058490:Disorder of Sex Development, 46,XY / Q000175:diagnosis* / Q000201:enzymology; D005260:Female; D006801:Humans; D007223:Infant; D011247:Pregnancy; D011296:Prenatal Diagnosis
chemical_list: D015067:17-Hydroxysteroid Dehydrogenases; C476565:17beta-hydroxysteroid dehydrogenase type 3