title: Early diagnosis of 5alpha-reductase deficiency in newborns.
abstract: 5Alpha-reductase-2 deficiency is a rare autosomal recessive form of 46,XY disorders of sex differentiation (DSD), caused by mutations in the steroid 5alpha-reductase type 2 gene (SRD5A2), presenting at birth with variable degrees of undervirilization. We report on three Italian newborns with 46,XY DSD in whom the evaluation of testosterone, dihydrotestosterone, testosterone/dihydrotestosterone (T/DHT) ratio and molecular analysis of the 5alpha-reductase type 2 gene was made in their first month of life. Baseline T/DHT ratio suggested 5alpha-reductase-2 deficiency; the diagnosis was confirmed by molecular genetics (homozygous mutation in exon 4 [G196S], heterozygous mutation in exon 1 and 5 [W35X/Y235F], heterozygous mutation plus polymorphism in exon 1 [G34W/A49T]). Proper investigation permitted early reassignment to male sex in two babies, assigned to female sex just after birth. In infancy, the T/DHT ratio, assessed by suitable assay methods and evaluated by age-appropriate reference values, seems to be able to select newborns affected by 5alpha-reductase-2 deficiency. Molecular analysis of the SRD5A2 gene should be warranted in newborns with abnormal ratio before sex assignment.
authors.affiliation: Adolescent Medicine Unit, Division of Pediatrics, S. Chiara Hospital, University of Pisa, Pisa, Italy. s.bertelloni@med.unipi.it
authors.forename: S
authors.initials: S
authors.lastname: Bertelloni
authors.forename: R T
authors.initials: RT
authors.lastname: Scaramuzzo
authors.forename: D
authors.initials: D
authors.lastname: Parrini
authors.forename: F
authors.initials: F
authors.lastname: Baldinotti
authors.forename: S
authors.initials: S
authors.lastname: Tumini
authors.forename: P
authors.initials: P
authors.lastname: Ghirri
mesh_terms: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase / Q000172:deficiency*; D012734:Disorders of Sex Development / Q000175:diagnosis* / Q000201:enzymology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male
chemical_list: D013741:3-Oxo-5-alpha-Steroid 4-Dehydrogenase; C476567:steroid-5alpha-reductase type 2