Molecular Analysis Of Steroidogenic Factor-1 (sf-1, Ad4bp,nr5a1) In 46, Xy Female Sex Reversal

Background and Objective:sex reversal syndrome characterised by discrepancy in karyotype and Phenotype is a hermaphrodism due to abnormity of Sex Determination and differentiation. Sex reversal syndrome is divided into 46,XX male and 46,XY female. Currently understanding of the molecular mechanism and signaling pathways for gonadal differentiation, and the genetic regulation of sexual differentiation of human are more problems than answers. Genetic analysis of genes involved in embryonic gonadal development and differentiation in sex reversal is a relatively convenient access. SF-1, also named NR5A1, FTZ-F1, Ad4BP, is an orphan nuclear receptor that regulates the transcription of many genes involved in sexual developmental and reproduction. It is a key transcription regulation gene involved in the hypothalamic- pituitary-steroidogenic axis. SF-1 knock-out mouse models exhibit complete adrenal and gonadal agenesis. More recently, identification of novel SF-1 mutations responsible for isolated 46,XY gonadal dysgenesis or 46,XX primary ovarian insufficiency, underscores its central role in the control and maintenance of adrenal and reproductive functions. Thus experimental evidence from studies suggests that mutation of NR5A1 causes 46,XY disorders of sex development, with or without adrenal failure. Our aim was to test the hypothesis that mutations in SF-1 cause 46,XY sex reversal.Methods:Collect the whole blood and serum of 6 cases of 46,XY female sex reversal patient to our hospital from January 2007 to 2009 September. Detecting serum sex hormones and cortisol was carried out at the first time.Genomic DNA was then extracted from peripheral blood leukocytes and exons 2-7 of the gene encoding SF-1 (NR5A1) were PCR-amplified. And direct sequencing was carried out to detect the mutation.Plasmid transfection and PCR-restriction enzyme digestion was applied to detect the results of DNA sequencing.Novel mutation was screened in 110 normal individuals who is unrelated persons with normal phenotypes to exclude the possibility of polymorphism.Results:A novel mutation of p.V128A and a polymorphic mutation of p.G146A in Exon4 in patient 4 was identified. We also detected the polymorphic mutation of p.G146A in the patient 1.We did not observe the novel mutation in 110 normal individuals. p.G146A in normal individuals was detected in 37.3% mutation rate.All patients were without adrenal insufficiency except Patient 2 whose cortisol is lower than normal value.Conclusion:Thus, We identified a novel SF-1 mutation in 46,XY sex reversal.We showed the 25% prevalence of SF-1 mutations in 46,XY sex reversal with low serum testosterone concentration. So it imply SF-1 mutations is a relatively frequent cause of 46,XY DSD in humans.