ESPE Abstracts

Background: Early genetic diagnosis in patients with disorders of sex development (DSDs) can facilitate clinical management, predict recurrence risks, and augment general knowledge. Novel techniques such as SNP microarrays, GWAS, and exome sequencing have identified mutations in the coding regions of genes linked to DSDs. In some instances, variants in non-coding regions have been associated with 46,XY gonadal dysgenesis, e.g. deletions upstream of SOX9 (PLoS One 2011; 6: e17793). Much less is known about chromosomal rearrangements affecting regulatory genome sequences and gene expression of other genes implicated in DSD.

Objective and hypotheses: To identify genomic copy number variants (CNVs) in non-coding regions that regulate gene expression associated with DSD.

Method: We utilized a whole genome array comparative hybridization (aCGH) to identify CNVs in patients with DSD. Fluorescence in situ hybridization (FISH) analysis and direct sequence analysis of the breakpoints were performed to characterize CNVs and their possible effects on the genomic regulatory landscape.

Results: Here, we present two patients with novel, de novo CNVs affecting the regulatory elements in the vicinity of the SOX8 and NR0B1 (DAX1) genes. Patient CHP-P46, a 46,XY phenotypic female who presented with skeletal anomalies and anemia, was found to have an 854 kb triplication involving evolutionary conserved enhancers upstream of SOX8. Genetic studies in CHP-P24, a 46,XX phenotypic male negative for SRY gene, detected an 80 kb deletion encompassing the NR0B1 gene as well as downstream enhancer and insulator sequences.

Conclusion: Genetic variants in non-coding sequences that disrupt long-distance transcriptional regulation of known DSD-causing genes were detected. The consequences of such genomic rearrangements on gene regulation need to be clarified. Analysis of such genomic alterations provides an invaluable opportunity to elucidate the role of sequence-conserved elements in gene regulation. Our findings reveal another level of complexity underlying the molecular mechanisms of DSD.