ESPE Abstracts

Background: Disorders of sex development (DSDs) refer to congenital disorders where the chromosomal, gonadal or anatomical sex is atypical. Patients typically present neonatally with ambiguous genitalia preventing immediate gender assignment or during adolescence where atypical sexual development becomes apparent. Genetic testing is key in establishing a diagnosis, allowing for personalised patient management and may significantly reduce the period of uncertainty for families regarding the sex of rearing of their child. Cytogenetics may provide guidance on possible causes and where further investigation is indicated, however a definitive molecular diagnosis is only made in around 20% of cases. Current DSD molecular testing strategies are not ideal, as tests for only a few of the many associated genes are currently available and require sequential testing.

Objective and hypotheses: To develop a targeted next generation sequencing (NGS) approach for the investigation of DSDs, This allows for multiple genes to be investigated simultaneously at a reduced cost compared to the current sequencing strategies. In addition, the time to diagnosis in many cases would be reduced.

Method: A TruSeq custom amplicon panel has been designed covering 32 genes associated with 46,XX and 46,XY DSD’s and across the sex development and steroid biosynthesis pathways. Sequencing is performed using the Illumina MiSeq.

Results: Assay validation has correctly identified the mutation status in 27 individuals. In addition a previously undiagnosed pathogenic mutation in the AR gene has been identified in one family.

Conclusion: The development of a DSD gene panel has increased the number of genes available for analysis in a diagnostic setting. The simultaneous testing allows for a streamlined and cost effective testing strategy. This DSD gene panel is now available on a diagnostic basis.