ESPE Abstracts

Background: 46,XY DSD occurs as a result of testicular developmental disorders, defect in androgen synthesis or action. Nowadays, the diagnosis of DSD is quite costly and it takes a considerable amount of time due to lengthy hormonal and genetic analysis.

Objective and hypotheses: The use of targeted next-generation sequencing of all known genes associated with 46 XY DSD for a fast molecular genetic diagnosis in patients in whom underlying defect of DSD was not previously diagnosed.

Method: Twenty paediatric patients with 46,XY DSD were recruited from Ege University, School of Medicine, Department of Pediatric Endocrinology. Firstly, androgen receptor (AR) and 5-alpha reductase (SRD5A2) gene mutations which are the most common causes of 46,XY DSD were excluded. The 46 genes that have been shown to be related to 46,XYDSD were sequenced by Illumina MiSeq Next Generation Sequencing System and the Illumina TruSight Exome Kit.

Results: The parents of 14 (66.7%) cases were consanguineous. A total of 9 (45%) mutations in four different genes were identified in 20 patients. Six mutations were novel. Mutations in the HSD17B3 gene were observed in six patients (30%). Two unrelated patients of these six patients carried p.Y287X mutation homozygously. Three other HSD17B3 gene mutations, p.T54A, p.R175T, p.R80Q, were detected in three unrelated patients in homozygous situation. One patient were compound heterozygous for the mutations p.R80Q/p.E93K in the HSD17B3gene. A heterozygous p.P396R mutation in WT-1gene in one of the patients with a suspicion of gonadal dysgenesis and in another case a hemizygous p.Q178X mutation in SRY gene were detected. One patient with a suspicion of testosterone production defect had a homozygous p.A483D mutation in LHCGR gene. All mutations were predicted to be pathogenic in in-silico analysis.

Conclusion: Targeted next-generation sequencing is an efficient, rapid and cost-effective technique for the mutation detection in genetically heterogeneous diseases such as 46,XYDSD. HSD17B3 gene mutations may be one of the most common causes of 46,XY DSD in societies having high rate of consanguineous marriages.

Funding: Ege University Research Committee 2014-BAP-0131.