Received June 21, 2007
Accepted on November 8, 2007

CLINICAL RESEARCH

ROBO2 Gene Variants Are Associated with Familial Vesicoureteral Reflux

Aida M. Bertoli-Avella ^*1, Maria Luisa Conte ^*, Francesca Punzo , Bianca M. de Graaf ^*, Giuliana Lama , Angela La Manna , Cesare Polito , Carolina Grassia , Bruno Nobili , Pier Francesco Rambaldi , Ben A. Oostra ^*, and Silverio Perrotta

*Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, Netherlands; and Department of Pediatrics, and Department of Radiological Sciences, Nuclear Medicine, Second University of Naples, Naples, Italy

¹ To whom correspondence should be addressed. E-mail: a.bertoliavella{at}erasmusmc.nl.

	Abstract

The SLIT2 receptor ROBO2 plays a key role in the formation of the ureteric bud, and its inactivation in mice leads to supernumerary ureteric bud development, lack of ureter remodeling, and improper insertion of the ureters into the bladder. Recently, two heterozygous ROBO2 missense mutations were identified in two families with primary vesicoureteral reflux occurring in combination with congenital anomalies of the kidney and urinary tract (VUR/CAKUT). This study investigated a possible causal role of ROBO2 gene variants in 95 unrelated patients with primary VUR (n = 78) or VUR/CAKUT. Eighty-two percent of all patients had a family history of genitourinary anomalies. Twenty-four ROBO2 gene variants were identified by direct sequencing of all 26 exons and the exon-intron boundaries. Of these, four led to amino acid substitutions: Gly328Ser, Asn515Ile, Asp766Gly, and Arg797Gln. When the families were examined, the missense variants co-segregated with VUR (three families) or VUR/CAKUT (one family). These variants were not found in 190 control subjects, and the affected amino acids have been conserved through evolution. In conclusion, a relatively high frequency of ROBO2 variants (5.1%) was found in familial cases; however, functional studies and validation in other cohorts are warranted.