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MAMLD1 (mastermind-like domain containing 1) is a recently discovered causative gene for 46,XY disorders of sex development (DSD), with hypospadias as the salient clinical phenotype. To date, microdeletions involving MAMLD1 have been identified in six patients, and definitive mutations (nonsense and frameshift mutations that are predicted to undergo nonsense mediated mRNA decay [NMD]) have been found in six patients. In addition, specific MAMLD1 cSNP(s) and haplotype may constitute a susceptibility factor for hypospadias. Furthermore, in vitro studies have revealed that (1) the mouse homolog is expressed in fetal Sertoli and Leydig cells around the critical period for sex development; (2) transient Mamld1 knockdown results in significantly reduced testosterone production primarily because of compromised 17α-hydroxylation and Cyp17a1 expression in Murine Leydig tumor cells; (3) MAMLD1 localizes to the nuclear bodies and transactivates the promoter activity of a non-canonical Notch target gene hairy/enhancer of split 3, without demonstrable DNA-binding capacity; and (4) MAMLD1 is regulated by steroidogenic factor 1 (SF1). These findings suggest that the MAMLD1 mutations cause 46,XY DSD primarily because of compromised testosterone production around the critical period for sex development. Further studies will provide useful information for the molecular network involved in fetal testosterone production., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Most of the patients with 5α-RD 2 deficiency are reared in the female social sex due to their severely undervirilized external genitalia but ~60% who have not been submitted to orchiectomy in childhood undergo male social sex change at puberty. In our cohort of 30 cases from 18 families, all subjects were registered in the female social sex except for two children-one who had an affected uncle and the other who was diagnosed before being registered. The majority of the patients were satisfied with the long-term results of their treatment and surprisingly, penile length was not associated with satisfactory or unsatisfactory sexual activity. Steroid 5α-RD2 deficiency should be included in the differential diagnosis of all newborns with 46,XY DSD with normal testosterone production before gender assignment or any surgical intervention because these patients should be considered males at birth., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)

Steroidogenic factor-1 (SF-1) (Ad4BP, NR5A1) is a nuclear receptor that plays a key role in adrenal and reproductive development and function. Deletion of the gene encoding Sf-1 (Nr5a1) in mice results in severe developmental defects of the adrenal gland and gonad. Consequently, initial work on the potential effects of SF-1 disruption in humans focused on individuals with primary adrenal failure, a 46,XY karyotype, complete gonadal dysgenesis, and Müllerian structures. This is a rare phenotype, but has been reported on two occasions, because of alterations that affect key DNA-binding domains of SF-1. Attention then turned to a potential wider role of SF-1 in human adrenal and reproductive disorders. Although changes in SF-1 only very rarely cause isolated adrenal failure, it is emerging that variations in SF-1 are a surprisingly frequent cause of reproductive dysfunction in humans. In 46,XY disorders of sex development, a spectrum of phenotypes has been reported including severe and partial forms of gonadal (testicular) dysgenesis, hypospadias, anorchia with microphallus, and even male factor infertility. In 46,XX females, alterations in SF-1 are associated with primary ovarian insufficiency. Thus, SF-1 seems be a more significant factor in human reproductive health than was first envisioned, with implications for adults as well as children., Competing Interests: The authors have no conflict of interest to declare., (Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.)