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No evidence for AT2R gene derangement in human urinary tract anomalies
M Hiraoka1, T Taniguchi, H Nakai
1Department of Pediatrics, Fukui Medical University School of Medicine, Fukui, Japan. hiraoka@fmsrsa.fukui-med.ac.jp
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 AT2R 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.
Insights
The angiotensin type 2 receptor (AT2R) gene disruption in mice causes kidney anomalies. However, this study found no significant role for the AT2R gene in human congenital anomalies of the kidney and urinary tract (CAKUT), particularly in the Japanese population.
Area of Science:
- Genetics
- Pediatric Nephrology
- Developmental Biology
Background:
- Congenital anomalies of the kidney and urinary tract (CAKUT) show sex-based prevalence, with renal hypoplasia being more common in males.
- A specific genetic variant (A-G transition) in the angiotensin type 2 receptor (AT2R) gene has been associated with CAKUT in Caucasian males.
- Previous research indicated a higher incidence of renal hypoplasia in Japanese boys.
Purpose of the Study:
- To investigate the role of the angiotensin type 2 receptor (AT2R) gene in the development of CAKUT in humans.
- To examine sex ratios for different types of CAKUT in the Japanese population.
- To determine if the A-G transition in the AT2R gene is associated with CAKUT in Japanese boys.
Main Methods:
- Analysis of sex ratios for various CAKUT types (renal hypoplasia, ureteropelvic junction stenosis, vesicoureteral reflux).
- Comparison of the frequency of the A-G transition in the AT2R gene between Japanese CAKUT patients and a control group.
- Genetic sequencing to detect mutations in the AT2R gene in patients with renal hypoplasia.
Main Results:
- Sex ratios for CAKUT in humans were variable and did not consistently show male predominance, unlike in mice.
- The frequency of the A-G transition in the AT2R gene was similar in both CAKUT patients and controls.
- No mutations in the AT2R gene were identified in Japanese boys with renal hypoplasia.
Conclusions:
- The AT2R gene does not appear to be a major factor in the development of renal hypoplasia and other CAKUT in the studied Japanese population.
- Findings suggest that the genetic basis for CAKUT in humans may differ significantly from that observed in mouse models.
- Further research is needed to elucidate the complex genetic and environmental factors contributing to CAKUT in humans.
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