Multicystic renal dysplasia, a histomorphological spectrum: Seven years experience from a tertiary care hospital.

OBJECTIVES: Multicystic dysplastic kidney (MCDK) is defined as the presence of multiple noncommunicating cysts of various sizes, detected sonographically, without evidence of functioning renal parenchyma on dimercaptosuccinic acid renal scan. It has an incidence of 1:4000 live births. They are more commonly diagnosed in boys, usually on the left side, but may also be bilateral. There is the presence of primitive ducts surrounded by fibromuscular connective tissue. These are because of the disturbed connection of the ureteric bud with renal blastema and abnormal division at the stage of metanephros, resulting in an abnormal metanephros differentiation. MATERIALS AND METHODS: Thirty cases of MCDK were included to study their histomorphology along with their clinical features. Cases were retrieved from the last seven years (2015-2021) from the Department of Pathology, Maulana Azad Medical College. RESULT: Age ranged from 10 days to 18 years. The cases were between 1 years and 5 years of age. Six out of 30 cases (20%) were infants with three of them being neonates. Twenty-one cases were males. All the cases had unilateral kidney involvement with the left kidney being involved in 20 out of 30 cases. Twenty-eight cases underwent nephrectomy in view of small contracted nonfunctional kidneys with one of them being horseshoe shaped. Five cases had associated hydronephrosis (two ipsilateral and three bilateral). One case had Hirshprung's disease, four had anorectal malformation, two had posterior urethral valves with vesicourethral reflux, one had duplex moiety, and one had undescended testes. On histopathological examination, all of them showed the presence of immature disorganized tubules surrounded by a collarette of immature mesenchymal stroma. One of the cases showed osteoid formation and four had areas of immature cartilage. Normal kidney parenchyma was seen at the periphery in four cases. CONCLUSION: This series has been presented to highlight the various histomorphological features of MCDK. MCDK can be managed conservatively in most of cases due to autoinvolution and, hence, needs to be differentiated from other close differentials like polycystic kidney disease, cystic nephroma, and cystic partially differentiated nephroblastoma in order to avoid unnecessary surgical intervention.

Differentiating pediatric cystic nephroma from common renal multicystic lesions: A case report.

Pediatric cystic nephroma is a rare, clinically benign, renal tumor. Pediatric renal cystic lesions are complex. Imaging findings and tumor appearance are often nonspecific, and careful pathological examination is necessary. We discuss diagnosis of pediatric cystic nephroma and how to differentiate it from multicystic dysplastic kidney and cystic partially differentiated nephroblastoma.

Cytogenomic aberrations in isolated multicystic dysplastic kidney in children.

BACKGROUND: Multicystic dysplastic kidney (MCDK) is a common form of congenital kidney anomaly. The cause of MCDK is unknown. We investigated whether MCDK in children is linked to cytogenomic aberrations. METHODS: We conducted array comparative genomic hybridization (aCGH) in ten unrelated children with MCDK. The pattern of inheritance was determined by real-time PCR in patients and their biological parents. RESULTS: Pathogenic aberrations were detected in three patients: a deletion at 7p14.3 with a size of 2.07 Mb housing 12 genes, including BBS9 (Bardet-Biedl syndrome 9) and BMPER (BMP binding endothelial regulator); a duplication at 16p13.11p12.3 with a size of 3.28 Mb that included >20 genes; and monosomy X for a female patient. The deletion at 7p14.3 was inherited from the patient's father, while the duplication at 16p13.11p12.3 was derived from the patient's mother. CONCLUSIONS: Up to 30% of patients with MCDK possess cytogenomic aberrations. BBS9 and BMPER variants have been reported to result in cystic kidney dysplasia, suggesting a possible pathogenic function for the deletion at 7p14.3 in children with MCDK. The duplication at 16p13.11p12.3 was not reported previously to associate with MCDK. Both variations were inherited from parents, indicating hereditary contributions in MCDK. Thus, aCGH is an informative tool to unravel the pathogenic mechanisms of MCDK. IMPACT: Cytogenomic aberrations are common in children with MCDK. Cytogenomic aberrations are inherited from parents, indicating hereditary contributions in MCDK. aCGH is a valuable tool to reveal pathogenic mechanisms of MCDK.

Presence of Cervical Vertebral Anomalies with Concomitant Non-Communicating Hydrocephalus and Multicystic Kidney in a Female Fetus: Where VACTERL-H Meets MURCS.

BACKGROUND: Congenital multisystemic lesions with co-occurrence of non-random malformations, such as VACTERL-H or MURCS association, often pose serious threads to the newborn and still constitute an antenatal diagnostic dilemma. CASE REPORT: A malformed fetus with VACTERL-H association at 20 gestational weeks had a skin-covered neural tube defect (NTD) of the lower cervical spine, concomitant hydrocephalus, as well as unilateral multicystic dysplastic kidney and the suspicion of mullerian duct anomaly as potentially assigned to MURCS association. DISCUSSION/CONCLUSION: We were able to demonstrate how well-defined, standardized volumetric reconstruction of diagnostic views displaying fetal pathology in utero might aid early and precise diagnosis of multi-organ malformations. Application of modern diagnostic imaging tools is helpful in delineation of the most likely diagnoses (VACTERL-H vs. MURCS) as further specified during detailed pathologic work-up and might consequently facilitate individually tailored interdisciplinary counseling, as in the case presented here.

TP63-mutation as a cause of prenatal lethal multicystic dysplastic kidneys.

BACKGROUND: Ectrodactyly-ectodermal dysplasia-clefting syndrome 3 (EEC) is one of the six overlapping syndromes caused by mutations in the tumor protein p63 gene (TP63). EEC is suspected when patients have cleft hands or feet, polydactyly, and syndactyly, abnormal development of the ectodermally derived structures, and orofacial clefting. Genitourinary (GU) anomalies have been identified in patients with EEC, yet these are often under-recognized and under-reported. The available literature on sonographic prenatal findings is sparse, especially when considering GU anomalies. METHODS: We present the case of a male stillborn fetus, who was found antenatally to have multicystic dysplastic kidneys and anhydramnios. Following the termination of pregnancy, examination and autopsy further revealed unilateral polydactyly and bilateral syndactyly which had not been previously identified on antenatal ultrasound. RESULTS: Whole-exome sequencing (WES) revealed a de novo heterozygous pathogenic variant in exon 5 of the TP63 gene: p.His247Arg: c.740A>G (NM_003722.4) which has been reported in the literature. The His247Arg variant has been published as a pathogenic variant in association with EEC, both with and without orofacial clefting. CONCLUSION: Our prenatal case expands the phenotypic spectrum of TP63-related disorders in general. In addition, it adds to the phenotype associated with the His247Arg pathogenic variant responsible for EEC. Further, we highlight the importance of WES as a postnatal tool to help clarify unexpected findings, and as a way to add to the spectrum of existing phenotypes of known single-gene disorders.

High Activation of the AKT Pathway in Human Multicystic Renal Dysplasia.

Multicystic renal dysplasia is a congenital cystic anomaly of the kidney caused by abnormal metanephric differentiation with immature tubules. It is surrounded by mesenchymal collars and islands of immature mesenchyma present between the cysts. The PI3K-AKT-mTOR signaling pathway is a key regulator involved in cell growth, proliferation, motility, survival, and apoptosis. Activation of the PI3K-AKT-mTOR pathway results in the survival and proliferation of tumor cells in many cancers. The aim of this study is to analyze the topographic expression of phospho-AKT, phospho-mTOR, and phospho-70S6K in renal development and in the multicystic dysplastic kidney (MCDK). A total of 17 fetal kidneys of development age from the first to the third trimester and 13 cases of pathological kidneys with MCDK were analyzed by immunohistochemistry in order to evaluate the expression of phospho-AKT (S473), phospho-mTOR, and phospho-70S6K. Phospho-AKT and phospho-mTOR were expressed early in renal development and in an identical manner for every structure derived from the ureteric bud, such as collecting ducts and urothelium. Phospho-p70S6K was expressed early in the urothelium and in glomerular mesangial cells. Later, their expressions differed according to the needs of cell proliferation and differentiation over time by becoming more selective. In MCDK, phospho-AKT, phospho-mTOR, and phospho-70S6K have the same profile: a high cytoplasmic expression in cystic epithelium, loose mesenchyma, and primitive tubes. This study demonstrates the essential and specific role of the PI3K-AKT-mTOR pathway in the formation of cysts in multicystic renal dysplasia.

Ligase IV syndrome can present with microcephaly and radial ray anomalies similar to Fanconi anaemia plus fatal kidney malformations.

Ligase IV (LIG4) syndrome is a rare disorder of DNA damage repair caused by biallelic, pathogenic variants in LIG4. This is a phenotypically heterogeneous condition with clinical presentation varying from lymphoreticular malignancies in developmentally normal individuals to significant microcephaly, primordial dwarfism, radiation hypersensitivity, severe combined immunodeficiency and early mortality. Renal defects have only rarely been described as part of the ligase IV disease spectrum. We identified a consanguineous family where three siblings presenting with antenatal growth retardation, microcephaly, severe renal anomalies and skeletal abnormalities, including radial ray defects. Autozygosity mapping and exome sequencing identified a novel homozygous frameshift variant in LIG4, c.597_600delTCAG, p.(Gln200LysfsTer33), which segregated in the family. LIG4 is encoded by a single exon and so this frameshift variant is predicted to result in a protein truncated by 678 amino acids. This is the shortest predicted LIG4 protein product reported and correlates with the most severe clinical phenotype described to date. We note the clinical overlap with Fanconi anemia and suggest that LIG4 syndrome is considered in the differential diagnosis of this severe developmental disorder.

Renal dysplasia masquerading as a renal mass in a child on hemodialysis.

Pathological renal mass is uncommon in children. It is important to differentiate this from a benign mass or mass-like lesion (pseudomass) for proper management. Renal dysplasia is a common finding in patients with end stage renal disease and can mimic a renal mass. Here, we report a 16-year-old girl on hemodialysis who was found to have a nodular right renal mass in the sonogram. Magnetic resonance imaging confirmed the nodular mass. She underwent right nephrectomy and the histopathology revealed features of renal dysplasia and end stage kidney disease without any evidence of malignancy. No further treatments were necessary. This case demonstrates that a nodular renal mass in dialysis patients does not always mean malignancy and could be a pseudomass from severe renal dysplasia. Since a sonogram may not be able to clearly define the etiology of solid mass in these patients, further evaluations including a renal histology and/or other imaging modalities are often necessary.

Immunohistochemistry and morphometric analysis of pelviureteric junction complexes in children with hydronephrosis.

AIM: The study aimed to analyze the musculature and innervations of pelviureteric junction (PUJ) complex and upper ureter by morphometry and immunohistochemistry in surgically resected specimens of PUJ obstruction and compares the findings with normal controls. MATERIALS AND METHODS: Specimens of the PUJ were obtained from twenty patients with hydronephrosis due to PUJ obstruction undergoing surgical treatment in this unit from 2013 to 2015. In the control group, seven PUJ complexes were taken from patients who had nephrectomy due to trauma and Wilms tumor. The sections were stained with H and E stain and elastic von Gieson stain. For immunohistochemistry, the tissue sections were immunostained by an indirect immunoperoxidase method for S-100 and neuron-specific enolase. RESULTS: Histopathologically, the predominant arrangement of muscle fibers was layered, i.e., a thick circular layer surrounded by two longitudinal layers on either side in PUJ of obstruction patients. S-100 immunoreactivity in the muscle layer showed dense neural innervation in PUJ complex of obstructed patients. CONCLUSIONS: Circular enhanced musculature may cause a sphincter-like activity with holding up of urine. The higher density of neuronal expression in PUJ might be responsible for causing constant contraction and intrinsic obstruction.

Neuronal defects an etiological factor in congenital pelviureteric junction obstruction?

INTRODUCTION: Congenital pelviureteric junction obstruction (PUJO) is one of the most frequent causes of neonatal hydronephrosis. Obstruction at the PUJ has potential severe adverse outcomes, such as renal damage. While pyeloplasty has been established as the definitive treatment, the exact pathophysiology of congenital PUJO remains unknown. Recent research has proposed neuronal innervation defects as an etiological factor in congenital PUJO. We aim to study the expression of various neuronal markers in PUJO specimens compared with controls, and evaluate whether severity of renal disease or dysfunction pre-operatively is related to expression of neuronal markers in resected PUJO specimens. MATERIALS AND METHODS: All consecutive patients who underwent dismembered pyeloplasty at KK Women's and Children's Hospital, Singapore, for intrinsic PUJO from 2008 to 2012 were included. Patients with other co-occurring renal pathologies were excluded. Controls were obtained from nephrectomy patients with Wilm's tumor or other benign renal conditions during the same period. Specimens were stained immunohistochemically with neuronal markers protein gene product 9.5 (PGP9.5), synaptophysin, and S-100, and with CD-117, a marker for interstitial cells of Cajal (Table). Levels of expression of the markers were assessed semiquantitatively (decreased, increased or no change) in comparison with controls by two independent observers. Pre-operative data of patients' renal anatomical (ultrasonography measurements of renal pelvis size) and functional parameters (differential renal function measured using MAG-3 renal scans) were obtained. DISCUSSION: Thirty-eight PUJO specimens (38 renal units) and 20 controls were studied. Mean patient age at pyeloplasty was 25.3 months (2.9-167.6 months). Median pre-operative pelvic size was 25.0 mm (17.0-50.0 mm). Both PUJO specimens and controls showed great heterogeneity in distribution of innervation. All four immunohistochemical markers were not predictive of significant pre-operative renal pelvis dilation or pre-operative diminished renal function of the operated kidney. CONCLUSIONS: There exists marked variability in expression of neuronal markers synaptophysin, PGP9.5, and S-100, and CD-117 in PUJO specimens compared with controls. Our results show no clinical significance of the expression of neuronal markers in predicting degree of pre-operative renal pelvis dilation or differential renal function. The heterogeneity of expression of neuronal markers in PUJO specimens and controls in our population is at variance with prior studies. The etiology of PUJO is likely to be complex and multifactorial.

[Upper urinary tract tumor and hydronephrosis to pelviureteric junction obstruction: a rare association]. / Tumeur de la voie excrétrice supérieure et hydronéphrose due à un syndrome de la jonction pyélo-urétérale: une association rare.

The association between tumor of the urinary tract and hydronephrosis caused by a syndrome of the pyelo-ureteral junction is rare. Indeed, tumors of the upper urinary tract and hydronephrosis have generally a cause-effect relationship. This last is due, more often, to an obstruction caused by a tumor of the ureter or of the pyelo-ureteral junction. We report the case of a 66-year old patient with a history of smoking and right pyelonephritis, presenting with right lumbar pain intermittently evolving over several months without haematuria. Ultrasound showed a dilation of the pyelocaliceal cavities with major reduction of the corticomedullary index of the right kidney. Uroscan was in favor of cystic dysplasia of the right kidney as well as of right hydronephrosis associated with syndrome of pyelo-ureteral junction with budding intrarenal images leading to the suspicion of pyelic tumor. The assessment was completed by urinary cytology which was positive. Right laparoscopic nephroureterectomy was performed and pathologic examination confirmed the diagnosis of urothelial carcinoma of the upper urinary tract.

Cyst-to-kidney volume ratio in the sonographic diagnosis of unilateral multicystic dysplastic kidney in children.

AIMS: To evaluate the usefulness of the cyst-to-kidney volume ratio determined by ultrasonography (US) in unilateral multicystic dysplastic kidney (MCDK) in children. MATERIAL AND METHODS: Our study group included 21 children (average age: 431 days) with unilateral MCDK and 22 children (average age: 440 days) with unilateral grade IV hydronephrosis due to ureteropelvic junction obstruction as the control group. All the children underwent transabdominal US. In children with MCDK, we calculated cyst-to-kidney volume ratios (volume of the largest cyst/volume of the MCDK) and in the control group the volume ratios of the renal pelvis and the largest calyx (volume of the pelvis or largest calyx/volume of the ipsilateral hydronephrotic kidney). Ellipsoid formula was used to calculate kidney and pelvis volumes. Sphere volume formula was used to calculate the largest cyst and calyx volumes. RESULTS: The mean cyst-to-kidney volume ratio (0.38±0.21) was significantly higher than the mean volume ratios of the renal pelvises (0.10±0.05) and the largest calyces (0.04±0.02) (p<0.05). There was no significant correlation between cyst-to-kidney volume ratio and the ages of the children (r=0.141, p=0.541). CONCLUSIONS:  With the aid of both the qualitative sonographic criteria and the newer data that we have proposed, US is a useful tool in the initial diagnosis of MCDK and for differentiation of MCDKs from grade IV hydronephrotic kidneys in children. The cyst-tokidney volume ratio is independent of age and thus, it can be helpful in the diagnosis of unilateral MCDK at any age.

Sarcoma sinovial renal primario: presentación de un caso con estudio molecular / Synovial sarcoma of the kidney: a case report with molecular analysis

El sarcoma sinovial (SS) renal fue descrito por primera vez por Argani et al. en el año 2000. Presentamos un caso de SS renal monofásico de grado intermedio. Se trata de un varón de 42 años que presentaba un tumor renal sólido-quístico de 6 cm bien delimitado, con un nódulo sólido de 1,5 cm. Se realizó nefrectomía parcial. El tumor se caracterizaba por células fusiformes monomorfas y quistes revestidos por células epiteliales en tachuela. Se observó infiltración focal de la grasa perirrenal que rodeaba el nódulo sólido. Las células fusocelulares expresaban CD99, BCL2, EMA y SMA, y eran negativas para S-100, CD34, receptores de estrógenos y progesterona, desmina y WT1. Las células en tachuela expresaban CD10, PAX8, PAX2, EMA, CKAE1-AE3, CK7 y CK19, confirmando que eran epitelio renal atrapado. Se realizó FISH que demostró la translocación t(X;18), específica del SS. El paciente ha recibido 4 ciclos de quimioterapia adyuvante y continúa libre de recurrencia o metástasis 9 meses tras la intervención (AU)

Synovial sarcoma (SS) of the kidney was first reported by Argani et al. in 2000. We report a case of a renal monophasic SS of intermediate grade in 42-year-old man with a solid-cystic, well-circumscribed, 6 cm renal mass containing a solid nodule of 1.5 cm. Partial nephrectomy was performed. The tumour was characterized by monomorphic spindle cells and cysts lined by trapped «hobnail» epithelial cells. Sections showed focal infiltration of perinephric fat surrounding the solid nodule. Spindle cells expressed CD99, BCL2, EMA and SMA and were negative for S-100, CD34, oestrogen and progesterone receptors, desmin and WT1. The 'hobnail epithelium' expressed CD10, PAX8, PAX2, EMA, CKAE1-AE3, CK7 and CK19, confirming its non-neoplastic and renal identity. FISH was performed and t(X;18) translocation, specific of SS, was demonstrated. The patient received 4 cycles of adjuvant chemotherapy and is alive without evidence of disease 9 months after surgery (AU)

Dermoid Cyst in a Multicystic Dysplastic Kidney: A Case Report and Literature Review.

Most multicystic dysplastic kidneys (MCDKs) are discovered prenatally. There is no consensus regarding initial workup and appropriate follow-up. We present a 9-year-old female who was fetally diagnosed with a MCDK and without follow-up returned with an 18-cm multicystic mass. The patient underwent laparoscopic nephrectomy. Final pathology revealed a dermoid cyst arising in a pediatric kidney, which to our knowledge has not been previously described. Patients with MCDK have hypertension as a possible sequela and possible reflux to their functioning kidney. Voiding cystourethrogram seems reasonable initially, and renal ultrasound is ideally noninvasive. Focused clinical awareness of the solitary kidney is important.

Conservative Management of Segmental Multicystic Dysplastic Kidney in Children.

OBJECTIVE: To assess the clinical characteristics and natural course of segmental multicystic dysplastic kidney (MCDK). METHODS: We retrospectively analyzed the medical records of 40 patients (43 renal units) diagnosed as having segmental MCDK between January 2002 and June 2014. Segmental MCDK was classified as typical when it was localized to the upper pole of a duplex collecting system, and otherwise as atypical. We investigated involution, associated anomalies requiring surgery, and complications of segmental MCDK. RESULTS: Of 43 renal units, 23 were typical and 20 were atypical. During 71.5 (interquartile range: 37.5-84.1) months of median follow-up period, complete and partial involution were observed in 48% and 26% of the typical group and 30% and 35% of the atypical group, respectively. In the typical group, involution was complete significantly earlier (P = .048) and ipsilateral anomalies were more frequently observed (P = .002). The initiation point of involution and contralateral anomalies were not different in the two groups. Hypertension developed in 1 case with contralateral MCDK and 1 case with contralateral renal agenesis. CONCLUSION: Segmental MCDK is not a rare disease entity, and conservative treatment appears to be sufficient with thorough follow-up, including regular monitoring of blood pressure and renal function, and with ultrasonography.

Determination of the severity of ureteropelvic junction obstruction using urinary epidermal growth factor and kidney injury molecule 1 levels.

AIM: This study aimed to assess the urinary concentrations of epidermal growth factor (EGF) and kidney injury molecule 1 (KIM-1) in patients with hydronephrosis. METHODS: Neonates with a history of prenatal hydronephrosis were enrolled in three groups. Group 1 included neonates with severe obstruction; group 2 included neonates with milder obstruction; and group 3 included neonates with normal findings on postnatal ultrasonography. RESULTS: 59 neonates were enrolled. The EGF: Cr and KIM-1: Cr ratios were significantly higher in group 1 than in group 2 (p = 0.016 and 0.015, respectively). The cut-off values were measured as 16.855 (sensitivity 71%, specificity 77%) and 0.4765 (sensitivity 81%, specificity 71%) for EGF:Cr and KIM-1:Cr ratios, respectively. The values were significantly higher in group 1 than in group 2. CONCLUSIONS: Evaluation of the urinary KIM-1:Cr ratio may help identify neonates with severe obstructive hydronephrosis.

Long-term follow-up results of laparoscopic pyeloplasty.

PURPOSE: To assess the long-term follow-up results of laparoscopic pyeloplasty for ureteropelvic junction obstruction. MATERIALS AND METHODS: Sixty-five patients (mean age, 43.8 years) who underwent standard laparoscopic pyeloplasty by transperitoneal approaches were enrolled in this study. The chief complaint was flank pain (n=57 patients); the remaining cases were detected incidentally. Twenty-three patients had undergone previous abdominal surgeries, including open pyeloplasty and endopyelotomy. Mean stricture length was 1.06 cm. Grade 3/4 and 4/4 hydronephrosis was detected in 36 and 14 patients, respectively. An obstructive pattern was present on the renal scan in 53 patients (81.5%). RESULTS: Fifty-seven patients were treated with dismembered Anderson-Hynes pyeloplasty and eight patients with Fenger pyeloplasty. During the operation, crossing vessels were found in 27 patients (41.5%). Mean operating time was 159.42 minutes. Although there were no cases of open conversion, two patients with colon and spleen injuries were detected postoperatively. The mean starting time of postoperative ambulation and diet was 1.54 days and 1.86 days, respectively. Mean hospital stay was 8.09 days. Mean follow-up period was 36.5 months. Follow-up intravenous pyelography and renal scan showed improvements in 59 patients, and the radiologic success rate was 90.8%. Eight patients showed failure on radiologic or symptomatic evaluation, and the overall success rate was 87.7%. In the comparative analysis between the success and failure groups, drained amount was the only risk factor related to failure (554.41 mL. vs. 947.70 mL, p=0.024). CONCLUSIONS: Long-term follow-up results support laparoscopic pyeloplasty as the standard treatment for ureteropelvic junction obstruction. Drained amount is a risk factor for failure of the operation.

PAX2 polymorphisms and congenital abnormalities of the kidney and urinary tract in a Brazilian pediatric population: evidence for a role in vesicoureteral reflux.

BACKGROUND AND OBJECTIVES: Congenital anomalies of the kidney and urinary tract (CAKUT) are common genetic malformations. Since the PAX2 gene has a role in kidney organogenesis, this study investigated the association of PAX2 gene polymorphisms with CAKUT in general and with specific phenotypes of CAKUT in a Brazilian pediatric population. METHODS: This study included 241 individuals with antenatal hydronephrosis and 259 healthy controls. For genotyping and allelic discrimination we used the probes to rs2077642, rs4244341, rs6421335, rs11190698, and rs11190693. RESULTS: No statistical differences in allele and genotype frequencies were observed for the single nucleotide polymorphism (SNP) rs11190693. At the SNPs rs4244341 and rs11190698, the frequencies of the ancestral alleles were significantly higher among CAKUT patients (rs4244341 allele G: 0.86 vs. 0.78; rs11190698 allele A: 0.85 vs. 0.79). At the SNP rs4244341, the genotype GG was increased in CAKUT group (0.72 vs. 0.61, P = 0.013), while the TT was higher in controls (0.01 vs. 0.05, P = 0.001). At the SNP rs11190698, the genotype CC was increased in controls (0.02 vs. 0.06, P = 0.01). The most frequent CAKUT phenotypes were vesicoureteral reflux (VUR), multicystic dysplastic kidney (MCDK), and ureteropelvic junction obstruction (UPJO). In patients with VUR, the frequencies of the monozygotic ancestral alleles decreased at the SNP rs11190693 (AA 0.13 vs. 0.26, P = 0.04) and increased at the SNP rs4244341 (GG 0.77 vs. 0.61, P = 0.03). No statistical differences were detected between controls and patients with UPJO and with MCDK for all SNPs. CONCLUSION: The PAX2 gene seems to be involved with the pathogenesis of VUR in our sample.