Mutations of SRY are the cause of complete pure gonadal dysgenesis (PGD) in 10-15% of patients. In the remaining individuals, it has been suggested that mutations in other genes involved in the testis-determining pathway could be causative. We describe the first report in which three cases of 46,XY complete PGD are attributed to mutations of the Desert hedgehog (DHH) gene. DHH was sequenced using genomic DNA from paraffin-embedded gonadal tissue from six patients with complete 46,XY PGD. Mutations were found in three patients: a homozygous mutation in exon 2, responsible for a L162P, and a homozygous 1086delG in exon 3. Mutated individuals displayed 46,XY complete PGD, differentiating from the only previously described patient with a homozygous DHH mutation, who exhibited a partial form of PGD with polyneuropathy, suggesting that localization of mutations influence phenotypic expression. This constitutes the first report where mutations of DHH are associated with the presence of 46,XY complete PGD, demonstrating that the genetic origin of this entity is heterogeneous and that disorders in other genes, different from SRY, involved in the testis-determining pathway are implicated in abnormal testicular differentiation in humans. These data extend previous reports demonstrating DHH is a key gene in gonadal differentiation.

Kallmann syndrome (KS) is characterized by the association of hypogonadotropic hypogonadism and anosmia or hyposmia. To date, 4 different genes have been identified as responsible for the presence of KS; however, in many cases no mutations have been found in any of these genes. Herein, we report the molecular findings regarding the analysis of fibroblast growth factor receptor 1 (FGFR1), prokineticin receptor 2 (PROKR2), and prokineticin (PROK2) in patients with KS. Twenty-four patients with KS were studied in whom mutations in KAL1 had been investigated previously. Polymerase chain reaction products from FGFR1, PROKR2, and PROK2 were sequenced and mutations were sought in the open reading frame of the 3 genes. Two patients presented a heterozygous T-to-G transversion in exon 2 (c.518T.G) of the PROKR2, which results in a leucine-to-arginine substitution at codon 173. Our results strengthen the hypothesis of possible digenic inheritance in some patients with KS. Likewise, our data extend previous reports demonstrating that PROKR2 plays a role in the etiology of this syndrome.

Aetiology of mixed gonadal dysgenesis (MGD) has not been completely elucidated. Molecular analyses have failed to demonstrate the presence of mutations in sex-determining region on Y chromosome (SRY); it has been suggested that these individuals may bear mutations in other genes involved in the testis-determining pathway. Desert hedgehog's (DHH) importance regarding male sex differentiation has been demonstrated in various studies we describe here, for the first time, two cases of MGD in which a monoallelic single base deletion in DHH is associated with the disorder. Genomic DNA was isolated from paraffin-embedded gonad tissue from 10 unrelated patients with MGD and three controls; in addition to, DNA from peripheral blood leukocytes in 100 controls. Coding sequence abnormalities in DHH were assessed by exon-specific PCR, single-stranded conformation polymorphism (SSCP) and direct sequencing. In two patients, a heterozygous 1086delG in exon 3 was found. Comparing previously described mutations in DHH to the one observed in this study, we can affirm that the phenotypic spectrum of patients with gonadal dysgenesis due to mutations in DHH is variable. This study continues to demonstrate the importance that DHH has in mammalian male sexual differentiation, providing extended evidence that DHH constitutes a key gene in gonadal differentiation.