No evidence for AT2R gene derangement in human urinary tract anomalies

Background. It has been recently found that mice, especially males, with a disrupted angiotensin type 2 receptor (AT2R) gene, which is located on the X-chromosome, often have a range of congenital anomalies of the kidney and urinary tract (CAKUT), including renal hypoplasia, and that Caucasian male patients with ureteropelvic junction stenosis (UPJ) and multicystic dysplastic kidneys frequently have A-G transition in intron 1 of the AT2R gene. We have previously found that renal hypoplasia is remarkably predominant in Japanese boys. Methods. We investigated sex ratios for the frequency of each CAKUT. The frequency of the A-G transition between the controls and 66 Japanese boys with CAKUT were compared. There was renal hypoplasia in 16, UPJ in 17, vesicoureteral in 20, and other anomalies in 13. We also investigated whether any mutations in A T2R genes were detectable in patients with renal hypoplasia. Results. In contrast to mice with a disruption of the AT2R gene, the male-to-female ratios in human patients proved to be considerably variable: 16 for renal hypoplasia, 2.1 for UPJ, 0.8 for vesicoureteral, and 1.2 for others. The frequency of the A-G transition was not different between the control population and the patients with CAKUT [31 of 102 (30%) vs. 23 of 66 (35%), respectively]. A sequencing study disclosed no mutations in nine boys with renal hypoplasia. Conclusions. These findings indicate that the AT2R gene may not play a major role in the development of renal hypoplasia and other CAKUT in humans, at least in the Japanese population.