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Background: Primary vesicoureteral reflux (VUR) is a common congenital anomaly of the kidney and urinary tract (CAKUT) in childhood. The present study identified the possible genetic contributions to primary VUR in children. Methods: Patients with primary VUR were enrolled and analysed based on a national multi-center registration network (Chinese Children Genetic Kidney Disease Database, CCGKDD) that covered 23 different provinces/regions in China from 2014 to 2019. Genetic causes were sought using whole-exome sequencing (WES) or targeted-exome sequencing. Results: A total of 379 unrelated patients (male: female 219:160) with primary VUR were recruited. Sixty-four (16.9%) children had extrarenal manifestations, and 165 (43.5%) patients showed the coexistence of other CAKUT phenotypes. Eighty-eight patient (23.2%) exhibited impaired renal function at their last visit, and 18 of them (20.5%) developed ESRD at the median age of 7.0 (IQR 0.9–11.4) years. A monogenic cause was identified in 28 patients (7.39%). These genes included PAX2 (n = 4), TNXB (n = 3), GATA3 (n = 3), SLIT2 (n = 3), ROBO2 (n = 2), TBX18 (n = 2), and the other 11 genes (one gene for each patient). There was a significant difference in the rate of gene mutations between patients with or without extrarenal complications (14.1% vs. 6%, P = 0.035). The frequency of genetic abnormality was not statistically significant based on the coexistence of another CAKUT (9.6% vs. 5.6%, P = 0.139, Chi-square test) and the grade of reflux (9.4% vs. 6.7%, P = 0.429). Kaplan–Meier survival curve showed that the presence of genetic mutations did affect renal survival (Log-rank test, P = 0.01). PAX2 mutation carriers (HR 5.1, 95% CI 1.3–20.0; P = 0.02) and TNXB mutation carriers (HR 20.3, 95% CI 2.4–168.7; P = 0.01) were associated with increased risk of progression to ESRD. Conclusions: PAX2, TNXB, GATA3 and SLIT2 were the main underlying monogenic causes and accounted for up to 46.4% of monogenic VUR. Extrarenal complications and renal function were significantly related to the findings of genetic factors in children with primary VUR. Like other types of CAKUT, several genes may be responsible for isolated VUR. [ABSTRACT FROM AUTHOR]

Congenital anomalies of the kidney and urinary tract (CAKUT) have been attributed to genetic and environmental factors. However, monogenic and copy number variations cannot sufficiently explain the cause of the majority of CAKUT cases. Multiple genes through various modes of inheritance may lead to CAKUT pathogenesis. We previously showed that Robo2 and Gen1 coregulated the germination of ureteral buds (UB), significantly increasing CAKUT incidence. Furthermore, MAPK/ERK pathway activation is the central mechanism of these two genes. Thus, we explored the effect of the MAPK/ERK inhibitor U0126 in the CAKUT phenotype in Robo2 PB/+ Gen1 PB/+ mice. Intraperitoneal injection of U0126 during pregnancy prevented the development of the CAKUT phenotype in Robo2 PB/+ Gen1 PB/+ mice. Additionally, a single dose of 30 mg/kg U0126 on day 10.5 embryos (E10.5) was most effective for reducing CAKUT incidence and ectopic UB outgrowth in Robo2 PB/+ Gen1 PB/+ mice. Furthermore, embryonic kidney mesenchymal levels of p-ERK were significantly decreased on day E11.5 after U0126 treatment, along with decreased cell proliferation index PHH3 and ETV5 expression. Collectively, Gen1 and Robo2 exacerbated the CAKUT phenotype in Robo2 PB/+ Gen1 PB/+ mice through the MAPK/ERK pathway, increasing proliferation and ectopic UB outgrowth. • Urinary system congenital anomalies are genetically and environmentally complex. • ROBO2 and GEN1 coregulate ureteral bud germination and influence CAKUT incidence. • U0126 treatment reduces CAKUT incidence in mice with Robo2 and Gen1 mutations. • We conclude that ROBO2 and GEN1 influence MAPK/ERK signaling to contribute to CAKUT. [ABSTRACT FROM AUTHOR]

Gestational diabetes mellitus (GDM) presents a substantial population health concern. Previous studies have revealed that GDM can ultimately influence nephron endowment. In this study, we established a GDM mouse model to investigate the embryological alterations and molecular mechanisms underlying the development of congenital anomalies of the kidney and urinary tract (CAKUT) affected by GDM. Our study highlights that GDM could contribute to the manifestation of CAKUT, with prevalent phenotypes characterized by isolated hydronephrosis and duplex kidney complicated with hydronephrosis in mice. Ectopic ureteric buds (UBs) and extended length of common nephric ducts (CNDs) were noted in the metanephric development stage. The expression of Ret and downstream p -ERK activity were enhanced in UBs, which indicated the alteration of RET/MAPK/ERK pathway may be one of the mechanisms contributing to the increased occurrence of CAKUT associated with GDM. • GDM could contribute to the manifestation of CAKUT in mice. • Ectopic UBs and extended length of CNDs were noted in the metanephric development stage under GDM. • GDM could alter the RET/MAPK/ERK pathway involved in metanephric development. [ABSTRACT FROM AUTHOR]

Congenital anomalies of the kidney and urinary tract (CAKUT) are a family of often-concurrent diseases with various anatomical spectra. Null-mutant Gen1 mice frequently develop multiple urinary phenotypes, most commonly duplex kidneys, and are ideal subjects for research on ectopic budding in CAKUT development. The upper and lower kidney poles of the Gen1 PB/PB mouse were examined by histology, immunofluorescence, and immunohistochemistry. The newborn Gen1 PB/PB mouse lower poles were significantly more hypoplastic than the corresponding upper poles, with significantly fewer glomeruli. On embryonic day 14.5, immediately before first urine formation, the upper pole kidney was already larger than the lower pole kidney. In vivo and in vitro, embryonic kidney upper poles had more ureteric buds than lower poles. Gen1 PB/PB embryos exhibited ectopic ureteric buds, usually near the original budding site, occasionally far away, or, rarely, derived from the primary budding site. Therefore, ectopia of the ureteric buds is the core of CAKUT formation. Further studies will be needed to investigate the regulatory roles of these genes in initial ureteric budding and subsequent ontogenesis during metanephros development. • Ectopia of the initial budding is central to the formation of CAKUT. • Three kinds of ectopic bud develop into three duplex kidneys in Gen1 PB/PB mice. • Upper pole kidney of newborn Gen1 PB/PB mice was more hypoplastic than that in lower. • At E14.5, the upper pole kidney was already larger than the lower pole kidney. • Ectopic budding alone results in kidney hypoplasia, not dysplasia in Gen1 mutation. [ABSTRACT FROM AUTHOR]

Intrauterine low-protein diet can affect kidney development and hence final nephron number. In this study, we reported that intrauterine low-protein diet can cause congenital anomalies of the kidney and urinary tract (CAKUT) phenotypes, which was dominated by the duplicated collecting system phenotype. At the same time, ectopic ureteric buds were increased under intrauterine low-protein diet and the number of UB branches was reduced in the serum-free culture. Intrauterine low-protein diet can change metanephric gene expression. Slit2/Robo2 and Spry1 expression levels were decreased, Ret expression was increased, and downstream p -Akt activity enhanced with apoptosis abnormal in ureteric bud tissue, which may be the mechanisms that intrauterine low-protein diet causes increased incidence of CAKUT in offspring. Thus, we showed correlation between intrauterine low-protein diet and CAKUT in offspring. • Intrauterine low-protein diet can cause CAKUT, which was dominated by the duplicated collecting system phenotype. • Ectopic ureteric buds were increased under intrauterine low-protein diet. • The number of UB branches was reduced in the serum-free culture. • Intrauterine low-protein diet can change metanephric gene expression. [ABSTRACT FROM AUTHOR]