Bladder exstrophy is a congenital anomaly in which the bladder protrudes through the abdominal wall. To identify genetic risk factors for this disorder, Heiko Reutter and colleagues performed a genome-wide association study and meta-analysis comprising 208 bladder exstrophy cases and 1,703 unaffected controls (PLoS Genet. 11, e1005024, 2015). In their combined analysis, they identified a cluster of common variants at 5q11.1 that were associated with a twofold higher risk of developing classic bladder exstrophy. The top candidate gene in this region, ISL1, encodes a transcription factor expressed in a wide range of developing tissues, including a broad domain of expression in the cloacal region during urogenital development. Notably, conditional knockout studies in mice have shown that Isl1 is required for normal kidney and ureteric development, supporting the suggestion that altered expression of ISL1 could contribute to the etiology of human congenital anomalies of the kidney and urinary tract and could underlie the newly discovered association between variants in the 5q11.1 region and genetic predisposition to bladder exstrophy.