ESPU Congress 2018 - Abstract Book

35 11–14 APRIL, 2018, HELSINKI, FINLAND S3: BASIC RESEARCH 2 Moderators: Magdalena Fossum (Sweden), Berk Burgu (Turkey) ESPU Meeting on Wednesday 11, April 2018, 15:35–17:05 15:35–15:38 S3-1 (PP) ★ FUNCTIONAL ANALYSIS OF TWO NEW VARIANTS IN BMP7 PRODOMAIN IN TWO PAIRS OF MONOZYGOTIC CONCORDANT TWINS WITH HYPOSPADIAS Aurore BOUTY  1 , Kelly WALTON  2 , Nurin LISTYASARI  3 , Gorjana ROBEVSKA  4 , Jocelyn VAN DEN BERGEN  4 , Sultana FARADZ  3 , Craig HARRISON  2 , Katie AYERS  4 and Andrew SINCLAIR  4 1) Royal Children's Hospital, *Urology, Parkville, AUSTRALIA - 2) Monash University, Growth Factor Therapeutics Laboratory, Department of Physiology, Clayton, AUSTRALIA - 3) Centre for Biomedical Research, Semarang, INDONESIA - 4) Murdoch Children's research institute, Molecular Development, Parkville, AUSTRALIA PURPOSE Variants in Bone Morphogenetic Protein 7 (BMP7) have been reported in patients with hypospadias. Here we analyse two variants in the BMP7 prodomain identified in twins with hypospadias. MATERIAL AND METHODS Patients with hypospadias were prospectively recruited. After informed consent DNA was extracted from blood. The coding regions of 1034 genes (including 64 known diagnostic genes for DSD, and 970 candidate genes) were sequenced using a targeted capture approach (Haloplex, Agilent), com- bined with massively parallel sequencing (MPS). The resulting variants were filtered for rarity in the general population (<1 %), and in our cohort. Quality, depth of the reads and predicted pathogenicity were also considered. Expression, localisation and activity of the variants were analysed in cell culture using immunofluorescence, western blots and luciferase reporter assays. RESULTS We have currently analysed sequencing from 46 patients with hypospadias. Two variants in BMP7 were identified in two pairs of monozygotic concordant twins exhibiting proximal hypospadias. Both variants are heterozygous, non-synonymous and affect highly conserved amino-acids in the prodo- main of BMP7, a region known to be important for the excretion of the protein into the extracellular matrix. Functional analyses demonstrated that both variants disrupt BMP7 synthesis or secretion. CONCLUSIONS Using our targeted DSD panel we have identified two new variants in the prodomain of BMP7 in hypospadias. By decreasing BMP7 secretion, these variants are likely to disrupt its role in the closure of the urethral plate. Further analysis of patients with hypospadias may uncover additional novel variants that cause this DSD.