ESPN 51th Annual Meeting

ESPN 2018


 
Mutations in BNC2 Lead to Autosomal-Dominant Lower Urinary Tract Obstruction (LUTO)
CAROLINE M. KOLVENBACH 2 SANDRA K. FRESE 3 GABRIEL C. DWORSCHAK 1 ANNA JAPP 4 JOHANNA M. SCHMIDT 2 Marcin Zaniew 5 William Newman 6 Glenda Beaman 6 Helen Stuart 6 Adrian S. Woolf 6 Raimondo Cervellione 6 Wolfgang Rösch 7 Stefanie Weber 8 Waldtraut Merz 9 Friedhelm Hildebrandt 10 Markus Feldkötter 1 Bernd Hoppe 1 Holger Thiele 11 Janine Altmüller 12 Christoph Berg 9 Michael Ludwig 13 Philipp Grote 14 Heiko Reutter 15 Benjamin Odermatt 2 Alina C. Hilger 1

1- DEPARTMENT OF PEDIATRICS, DIVISION OF PEDIATRIC NEPHROLOGY, UNIVERSITY HOSPITAL BONN, BONN, GERMANY
2- INSTITUTE OF ANATOMY, UNIVERSITY OF BONN, BONN, GERMANY
3- INSTITUTE OF HUMAN GENETICS, UNIVERSITY OF BONN, BONN, GERMANY
4- INSTITUTE OF NEUROPATHOLOGY, UNIVERSITY OF BONN MEDICAL CENTER, BONN, GERMANY
5- CHILDRENS HOSPITAL, POZNAń, POLAND
6- INSTITUTE OF HUMAN DEVELOPMENT, FACULTY OF MEDICAL AND HUMAN SCIENCES, UNIVERSITY OF MANCHESTER, MANCHESTER ACADEMIC HEALTH SCIENCE CENTRE AND THE ROYAL MANCHESTER CHILDRENS AND ST MARYS HOSPITALS, MANCHESTER, UNITED KINGDOM
7- PEDIATRIC UROLOGY, UNIVERSITY MEDICAL CENTER REGENSBURG, REGENSBURG, GERMANY
8- DEPARTMENT OF PEDIATRICS, UNIVERSITY HOSPITAL MARBURG, MARBURG, GERMANY
9- DEPARTMENT OF OBSTETRICS AND PRENATAL MEDICINE, UNIVERSITY OF BONN, BONN, GERMANY
10- DIVISION OF NEPHROLOGY, DEPARTMENT OF MEDICINE, BOSTON CHILDRENS HOSPITAL, HARVARD MEDICAL SCHOOL, BOSTON, MA, UNITED STATES
11- COLOGNE CENTER FOR GENOMICS, UNIVERSITY OF COLOGNE, COLOGNE, GERMANY
12- CENTER FOR MOLECULAR MEDICINE COLOGNE, UNIVERSITY OF COLOGNE, COLOGNE, GERMANY
13- DEPARTMENT OF CLINICAL CHEMISTRY AND CLINICAL PHARMACOLOGY, UNIVERSITY OF BONN, BONN, GERMANY
14- INSTITUTE OF CARDIOVASCULAR REGENERATION, CENTER FOR MOLECULAR MEDICINE, GOETHE UNIVERSITY, FRANKFURT AM MAIN, GERMANY
15- DEPARTMENT OF NEONATOLOGY AND PEDIATRIC INTENSIVE CARE, CHILDRENS HOSPITAL, UNIVERSITY OF BONN, BONN, GERMANY
 
Introduction:

Congenital “lower urinary tract obstruction” (LUTO) is defined by a decrease in the free passage of urine through the urethra. About three out of 10,000 pregnancies are affected, the etiology is so far unknown.

Material and methods:

Whole exome sequencing (WES) in a family with 4 affected from 3 generations was performed. 258 LUTO patients were screened for further variants in the identified candidate gene BNC2 using Sanger sequencing. Functional studies comprised in situ hybridization (ISH) studies in mouse embryos, translational knock-down (KD) in developing zebrafish larvae (zfl) using Morpholino oligonucleotides (MO) and co-injection of human BNC2 mRNA with the Bnc2-MO in zfl as well as overexpression of BNC2 mRNA in zfl.

Results:

Filtering of WES Data revealed a nonsense mutation (c.2554C>T; p.Arg852*) in BNC2 (basonuclin 2). Out of 258 LUTO patients one additional family (affected father and son) carrying a novel missense mutation (c.2663A>G, p.H888R) in BNC2 could be identified. Functional characterization of BNC2 using ISH showed expression at E13.5 in developing mouse urethra. KD of bnc2 by injection MO in zfl caused cloacal obstruction with formation of a vesicle at the distal end of pronephric duct in 10% of zfl and zystic dilated deformed glomeruli and dilated pronephric ducts in 50%. Co-injection of human BNC2 mRNA with Bnc2-MO in zfl showed no rescue of the phenotype which is expected since already slight overexpression of human BNC2 mRNA in zfl lead to the same phenotype as KD confirming the specificity of the Bnc2-MO suggesting that the observed phenotypes in fish and human are the result of gene dosage disbalance of BNC2.

Conclusions:

Human genetic and developmental biology models suggest BNC2 as the first monogenic cause of LUTO.