Copy number variants suggest different molecular pathways for the pathogenesis of bladder exstrophy

Bladder exstrophy is a rare congenital malformation leaving the urinary bladder open in the midline of the abdomen at birth. There is a clear genetic background with chromosome aberrations, but so far, no consistent findings apart from 22q11-duplications detected in about 2%-3% of all patients. Some genes are implicated like the LZTR1, ISL1, CELSR3, and the WNT3 genes, but most are not explained molecularly. We have performed chromosomal microarray analysis on a cohort of 140 persons born with bladder exstrophy to look for submicroscopic chromosomal deletions and duplications. Pathogenic or possibly pathogenic microdeletions or duplications were found in 16 patients (11.4%) and further 9 with unknown significance. Two findings were in regions linked to known syndromes, two findings involved the same gene (MCC), and all other findings were unique. A closer analysis suggests a few gene networks that are involved in the pathogenesis of bladder exstrophy; the WNT-signaling pathway, the chromosome 22q11 region, the RIT2 and POU families, and involvement of the Golgi apparatus. Bladder exstrophy is a rare malformation and is reported to be associated with several chromosome aberrations. Our data suggest involvement of some specific molecular pathways.