Gene dosage imbalances in patients with 46,XY gonadal DSD detected by an in‐house‐designed synthetic probe set for multiplex ligation‐dependent probe amplification analysis

Abstract

The development of a testis requires the proper spatiotemporal expression of the SRY gene and other genes that act in a dosage-sensitive manner. Mutations in the SRY gene account for only 10-15% of patients with 46,XY gonadal disorder of sex development (DSD). To enable the diagnostics of deletions and duplications of genes known to be involved in different forms of DSD, we developed a synthetic probe set for multiplex ligation-dependent probe amplification (MLPA) analysis. Here, we report the results from the analysis of 22 patients with 46,XY gonadal DSD. The analysis with the DSD probe set has led to the identification of two copy number variations, an 800-kb NR0B1 (DAX1) locus duplication on Xp21 in a patient with isolated partial gonadal dysgenesis and a duplication of the SRD5A2 gene that represents a rare normal variant. The described MLPA kit represents an optimal complement to DNA sequence analysis in patients with DSD, enabling screening for deletions and duplications of several genes simultaneously. Furthermore, the second identification of an NR0B1 locus duplication in a patient with isolated gonadal dysgenesis, without dysmorphic features and/or mental retardation, highlights the importance of evaluating NR0B1 duplication in patients with gonadal dysgenesis.

Case Report Molecular characterisation of a der(Y)t(Xp;Yp) with Xp functional disomy and sex reversal

“…region of the NR0B1 gene resulting in incomplete DSS (Barbaro et al, 2008). In contrast, the patient reported here has a breakpoint that is further centromeric, containing the entire NR0B1 gene and control elements and therefore exhibiting complete DSS.…”

“…Sex reversal due to Xp21 disomy is rare and has been observed as a result of an interstitial duplication of Xp21, an X;A translocation or an X;Y translocation (Sanlaville et al, 2004;Barbaro et al, 2007Barbaro et al, , 2008Tzschach et al, 2008). The patient reported here is one of a small number of reported cases resulting from an X;Y translocation (Table 3), and the only one that has been resolved at the level of oligonucleotide-based CMA.…”

“…Duplication of this region, which would otherwise be subject to X-inactivation, is associated with isolated gonadal dysgenesis together with a range of extragonadal abnormalities (Barbaro et al, 2008). We report here a 46,X,+mar female carrying a rare unbalanced t(Xp;Yp) rearrangement, together with a high-resolution analysis of the X-chromosome breakpoint.…”

Pubertal androgenization and gonadal histology in two 46,XY adolescents with NR5A1 mutations and predominantly female phenotype at birth

“…Trace data were analyzed using the Gene Mapper v3.7 software and exported to an Excel spreadsheet (Microsoft). Analysis, using peak heights, was performed as described previously (20).…”

Prevalence of SRY and DAX-1 gene deletion in patients with Cryptorchidism and Hypospadias – A Pilot study in North Indian Children

“…Because XY individuals deleted for DSS develop as males it can be proposed that DAX1 is required for ovarian but not testicular development and that its action should be turned off in XY genital ridge to avoid interference with testis development. 25 A study done in Italy by Barbaro M, et al in 2008 had shown in 46 XY gonadal dysgenesis identified two copy number variations, duplication of DAX1 gene, indicaing that DAX 1 is not required for the development of testis. But recent studies done in mice model suggest that DAX1 is required for the development of testis.…”