Renal dysplasia in the neonate

Distinguishing Features of Childhood Renal Dysplasia

BACKGROUND

Renal dysplasia (RD) is a major cause of chronic kidney disease (CKD) in childhood. Herein, we present a single-center experience about distinctive features of different subtypes of dysplasia.

METHODS

All children with RD admitted between January 2018 and June 2019 were included in this cross-sectional study. Patients were classified as having unilateral RD, bilateral RD, posterior urethral valves (PUV), and multicystic-dysplastic kidneys (MCDK).

RESULTS

A total of 198 patients (108 unilateral RD, 31 bilateral RD, 16 PUV, and 43 MCDK) with a follow-up period of 80 (1.5-240) months were included. The overall consanguinity rate was 22%, whereas it was 56% in bilateral RD patients. Two-thirds had additional urogenital anomalies. Hypertension was detected in 16% of the patients, and 20% had median proteinuria of 16 (5.2-173) mg/m2/h, which was significantly higher in the PUV and bilateral RD groups. The overall rate of CKD was 23%, which was more frequent in bilateral RD and PUV groups. The median age at end-stage renal disease was 91.5 (0.5-208) months, including 12 renal transplant patients.

CONCLUSIONS

As different subtypes of RD have distinct clinical and prognostic features, the follow-up of RD patients should be individualized, and modifiable complications such as proteinuria and HT should be monitored closely.

Congenital Anomalies of the Kidneys and Urinary Tract

Congenital anomalies of the kidneys and urinary tract encompass the spectrum of disorders that include the kidneys, ureters, bladder, and urethra. These abnormalities often lead to altered renal size and location, dysplastic changes in the kidney parenchyma, and anomalies in the collecting system. Though the etiology of each of these conditions can be variable, it is known that the collection of these defects represent 40% to 50% of all pediatric end-stage renal disease worldwide. The multifaceted management of these conditions is aimed at preserving kidney function and ultimately delaying the need for transplantation. With the advancement of prenatal ultrasonographic techniques, these conditions are more likely to be diagnosed before birth, which often leads to rapid postnatal intervention and better outcomes.

Cystic Kidney Diseases in Children and Adults: Differences and Gaps in Clinical Management

Cystic kidney diseases, when broadly defined, have a wide differential diagnosis extending from recessive diseases with a prenatal or pediatric diagnosis, to the most common autosomal-dominant polycystic kidney disease primarily affecting adults, and several other genetic or acquired etiologies that can manifest with kidney cysts. The most likely diagnoses to consider when assessing a patient with cystic kidney disease differ depending on family history, age stratum, radiologic characteristics, and extrarenal features. Accurate identification of the underlying condition is crucial to estimate the prognosis and initiate the appropriate management, identification of extrarenal manifestations, and counseling on recurrence risk in future pregnancies. There are significant differences in the clinical approach to investigating and managing kidney cysts in children compared with adults. Next-generation sequencing has revolutionized the diagnosis of inherited disorders of the kidney, despite limitations in access and challenges in interpreting the data. Disease-modifying treatments are lacking in the majority of kidney cystic diseases. For adults with rapid progressive autosomal-dominant polycystic kidney disease, tolvaptan (V2-receptor antagonist) has been approved to slow the rate of decline in kidney function. In this article, we examine the differences in the differential diagnosis and clinical management of cystic kidney disease in children versus adults, and we highlight the progress in molecular diagnostics and therapeutics, as well as some of the gaps meriting further attention.

Genetic Etiologies, Diagnosis, and Management of Neonatal Cystic Kidney Disease

Fetal kidney development is a complex and carefully orchestrated process. The proper formation of kidney tissue involves many transcription factors and signaling pathways. Pathogenic variants in the genes that encodethese factors and proteins can result in neonatal cystic kidney disease. Advancements in genomic sequencing have allowed us to identify many of these variants and better understand the genetic underpinnings for an increasing number of presentations of childhood kidney disorders. This review discusses the genes essential in kidney development, particularly those involved in the structure and function of primary cilia, and implications of gene identification for prognostication and management of cystic kidney disorders.

Case Report: Candidate Genes Associated With Prenatal Ultrasound Anomalies in a Fetus With Prenatally Detected 1q23.3q31.2 Deletion

Background: Patients with deletions involving the long arm of chromosome 1 are rare, and the main aim of this study was to refine the genotype-phenotype correlation.

Case Report: In this report, a 28-year-old pregnant woman, gravida 2 para 1, at 25⁺⁴ weeks of gestation underwent ultrasound examination in our institute. The ultrasonographic findings of the fetus were as follows: (1) fetal growth restriction; (2) cleft lip and palate; (3) bilateral renal hypoplasia; (4) lateral ventriculomegaly; (5) single umbilical artery; (6) absent stomach; (7) coronary sinus dilatation with persistent left superior vena cava, ventricular septal defect and unroofed coronary sinus syndrome. Chromosomal microarray analysis of amniotic fluid from the fetus revealed a 28.025 Mb deletion in 1q23.3q31.2, spanning from position 164,559,675 to 192,584,768 (hg19).

Conclusion: Genotype-phenotype correlation might improve prenatal diagnosis of fetuses with chromosome 1q deletion. PBX1 could be a candidate gene for fetal growth restriction, renal hypoplasia and congenital heart disease. Fetal growth restriction was accompanied by decreased renal volume in the fetus. Combined with ultrasonic examination, the application of chromosomal microarray analysis will provide accurate prenatal diagnosis.

Comprehensive Metabolic Signature of Renal Dysplasia in Children. A Multiplatform Metabolomics Concept

Renal dysplasia is a severe congenital abnormality of the kidney parenchyma, which is an important cause of end-stage renal failure in childhood and early adulthood. The diagnosis of renal dysplasia relies on prenatal or postnatal ultrasounds as children show no specific clinical symptoms before chronic kidney disease develops. Prompt diagnosis is important in terms of early introduction of nephroprotection therapy and improved long-term prognosis. Metabolomics was applied to study children with renal dysplasia to provide insight into the changes in biochemical pathways underlying its pathology and in search of early indicators for facilitated diagnosis. The studied cohort consisted of 72 children, 39 with dysplastic kidneys and 33 healthy controls. All subjects underwent comprehensive urine metabolic profiling with the use of gas chromatography and liquid chromatography coupled to mass spectrometry, with two complementary separation modes of the latter. Univariate and multivariate statistical calculations identified a total of nineteen metabolites, differentiating the compared cohorts, independent of their estimated glomerular filtration rate. Seven acylcarnitines, xanthine, and glutamine were downregulated in the urine of renal dysplasia patients. Conversely, renal dysplasia was associated with higher urinary levels of dimethylguanosine, threonic acid or glyceric acid. This is the first metabolomic study of subjects with renal dysplasia. The authors define a characteristic urine metabolic signature in children with dysplastic kidneys, irrespective of renal function, linking the condition with altered fatty acid oxidation, amino acid and purine metabolisms.

Shaping of the nephron - a complex, vulnerable, and poorly explored backdrop for noxae impairing nephrogenesis in the fetal human kidney

Background

The impairment of nephrogenesis is caused by noxae, all of which are significantly different in molecular composition. These can cause an early termination of nephron development in preterm and low birth weight babies resulting in oligonephropathy. For the fetal human kidney, there was no negative effect reported on the early stages of nephron anlage such as the niche, pretubular aggregate, renal vesicle, or comma-shaped body. In contrast, pathological alterations were identified on subsequently developing S-shaped bodies and glomeruli. While the atypical glomeruli were closely analyzed, the S-shaped bodies and the pre-stages received little attention even though passing the process of nephron shaping. Since micrographs and an explanation about this substantial developmental period were missing, the shaping of the nephron in the fetal human kidney during the phase of late gestation was recorded from a microanatomical point of view.

Results

The nephron shaping starts with the primitive renal vesicle, which is still part of the pretubular aggregate at this point. Then, during extension of the renal vesicle, a complex separation is observed. The medial part of its distal pole is fixed on the collecting duct ampulla, while the lateral part remains connected with the pretubular aggregate via a progenitor cell strand. A final separation occurs, when the extended renal vesicle develops into the comma-shaped body. Henceforth, internal epithelial folding generates the tubule and glomerulus anlagen. Arising clefts at the medial and lateral aspect indicate an asymmetrical expansion of the S-shaped body. This leads to development of the glomerulus at the proximal pole, whereas in the center and at the distal pole, it results in elongation of the tubule segments.

Conclusions

The present investigation deals with the shaping of the nephron in the fetal human kidney. In this important developmental phase, the positioning, orientation, and folding of the nephron occur. The demonstration of previously unknown morphological details supports the search for traces left by the impairment of nephrogenesis, enables to refine the assessment in molecular pathology, and provides input for the design of therapeutic concepts prolonging nephrogenesis.

Renal transplant from infant and neonatal donors is a feasible option for the treatment of end-stage renal disease but is associated with increased early graft loss

Kidney transplants from young pediatric donors are uncommonly performed in the UK. Published literature of kidney transplant from donors weighing less than 5 kg is sparse. We present our initial experience of en bloc kidney transplantation (EKT) from donors weighing less than 20 kg, including neonatal donors. All recipients undergoing EKT from donors under 20 kg at our center from January 2005 to October 2016 were included. Donor and recipient details were recorded from a prospective database. Electronic patient records were examined for follow-up data. Of 30 EKTs included, 15 were from ≤5 kg donors and 15 from >5 kg donors (median weight 3.4 and 12.7 kg, respectively). One-year graft survival for ≤5 kg and >5 kg donors for EKT was 86.7% and 93.3% (P = 0.85), respectively. Progressive improvement in estimated GFR (eGFR) was noted in both donor categories through first-year posttransplant but in the ≤5 kg donor category significant improvement was seen at 12 months compared to 3 months after transplantation (median eGFR 37.3 vs 70.0 mL/min/1.73 m² , P = 0.03). Two early graft losses were attributable to early vascular complications and one graft loss due to primary nonfunction. Our data show that kidney transplantation from such donors is a feasible option at centers with experience of EKT, albeit with increased risk of early graft loss.

Pediatric kidney transplantation

Since first performed in 1954, kidney transplantation has evolved as the preferred long-term treatment of children with end stage renal disease (ESRD). The etiology of chronic kidney disease (CKD) and ESRD in children is broad and can be quite complicated, necessitating a multidisciplinary team to adequately care for these patients and their myriad needs. Precise surgical techniques and modern protocols for immunosuppression provide excellent long-term patient and graft survival. This article reviews the many etiologies of renal failure in the pediatric population focusing on those most commonly leading to the need for kidney transplantation. The processes of evaluation, kidney transplantation, short-term and long-term complications, as well as long-term outcomes are also reviewed.