Papillorenal Syndrome Research Articles

Family Planning in Genetic Optic Atrophies in Israel, a Case Series and a Discussion of Ethical Considerations.

Patients with genetic optic atrophies must navigate all stages of life with their visual impairment, including the important milestone of family planning. Advances in genetic testing now allows physicians and affected families to consider medical help with the aim of preventing blindness through preconception, preimplantation, and perinatal methods. This case series presents 4 patients with different genetic optic atrophies (Leber hereditary optic neuropathy [LHON], autosomal dominant optic atrophy, Wolfram syndrome, and papillorenal syndrome) who were followed by the Neuro-Ophthalmology Unit at a tertiary medical center between 2010 and 2023 and were of child-bearing age. The aim of this study was to increase understanding in family planning options for patients with optic atrophies, raise awareness of the solutions available, and provide guidance for clinicians to support their patients. Advances in medicine, genetics, and medical technology allow multidisciplinary teams to assist patients in fulfilling their desire for a genetically healthy offspring. Customized solutions can be designed to meet the specific challenges posed by each type of genetic optic atrophy. The solutions proposed in this series are based on genetic testing done in the parents, which then allows to plan medical and genetic intervention individually. The solutions opted for in this series range from the decision to not have another child until PGD (Preimplantation genetic diagnosis). We describe how genetic advancements have made it possible for patients with the 4 most common hereditary optic atrophies to fulfill their wish to have children without visually threatening genetic mutations. We also review the recent literature on the penetrance of optic atrophy in OA-mutation carriers and raise 2 significant ethical considerations: the reduction of a future life to a non-life-threatening impairment and that of public expenditure for non-life-threatening conditions.

Familial focal segmental glomerulosclerosis with Alport-like glomerular basement changes caused by paired box protein 2 gene variant

Paired box protein 2 (PAX2) gene variant causes renal coloboma syndrome (MIM#120330). Further, they are associated with focal segmental glomerulosclerosis and characterized by basement membrane changes similar to Alport syndrome.Herein, we report an 8-year-old boy who presented with proteinuria and decreased renal function. His paternal uncle has focal segmental glomerulosclerosis and renal failure, and his paternal grandmother has renal failure and is receiving peritoneal dialysis. Further, his father has stage 2 chronic kidney disease. At 3 years of age, his serum creatinine-estimated glomerular filtration rate was 40–50 mL/min/1.73 m2. At 8 years of age, his renal function further decreased and he had proteinuria (urinary protein/Cr 3.39 g/g Cr). Renal histopathology showed oligonephronia and focal segmental glomerulosclerosis. A partial basket-weave pattern, similar to Alport syndrome, was also observed on a transmission electron microscope, and low-vacuum scanning electron microscopy revealed coarse meshwork changes in the glomerular basement membrane. Genetic analysis revealed a PAX2 heterozygous variant (NM_003987.4:c.959C > G), a nonsense variant in which the serine at position 320 changes to a stop codon, in our patient and his father. PAX2 is a transcription factor that is important for the podocyte variant. However, podocytes with PAX2 gene variants may cause abnormal basement membrane production and repair, thereby resulting in Alport-like changes.

Papillorenal syndrome with extensive retinoschisis

Papillorenal syndrome with extensive retinoschisis

PAX2 Gene Mutation in Pediatric Renal Disorders-A Narrative Review.

The PAX2 gene is a transcription factor that is essential for the development of the urinary system among other transcription factors. The role of PAX2 is highlighted from the seventh week of gestation, when it is involved in development processes and the emergence of nephrons and collecting tubes. Being an important factor in renal development, mutations of this gene can produce severe alterations in the development of the urinary tract, namely congenital anomalies of the kidneys and urinary tract. The first reported cases described with the PAX2 mutation included both renal anomalies and the involvement of other organs, such as the eyes, producing renal coloboma syndrome. Over the years, numerous cases have been reported, including those with only renal and urinary tract anomalies. The aim of this review is to present a summary of pediatric patients described to have mutations in the PAX2 gene to contribute to a better understanding of the genetic mechanism causing anomalies of the kidneys and urinary tract. In this review, we have included only pediatric cases with renal and urinary tract disorders, without the involvement of other organs. From what we know so far from the literature, this is the first review gathering pediatric patients presenting the PAX2 mutation who have been diagnosed exclusively with renal and urinary tract disorders.

PAX 2 Mutation in an Indian Family with Renal Coloboma Syndrome

The transcription factor encoded by the PAX2 gene plays a significant role in the development of the urogenital tract, eyes, ears, and central nervous system. Heterozygous mutations in the PAX2 gene cause renal coloboma syndrome, a rare autosomal dominant disorder characterized by optic nerve coloboma and renal anomalies. In this study, two siblings with chronic kidney disease (CKD) receiving regular dialysis therapy were investigated. DNA sequencing was performed on blood samples from both patients, which revealed four novel heterozygous variations in the PAX2 gene in both patients. Sequencing analysis showed a C to G transversion at position c.352 of the PAX2 gene in a heterozygous state.

A rare case report: Renal coloboma syndrome

Renal coloboma syndrome (RCS), also called papillorenal syndrome, is a rare syndrome characterized by renal abnormalities and optic nerve dysplasia. We present a case of a neonate with renal and eye abnormalities. Along with the known diagnosis of multicystic dysplastic kidney, the neonate was diagnosed with coloboma of the right eye, making a probable diagnosis of RCS. Retinal detachment and decreased visual acuity are implications of the ocular malformations. Hypertension, proteinuria, and renal insufficiency, which frequently lead to end-stage kidney disease, are serious consequences of renal dysplasia.

PAX2 and CAKUT Phenotypes: Report on Two New Variants and a Review of Mutations from the Leiden Open Variation Database

PAX2 is a transcription factor expressed during embryogenesis in the eye, ear, CNS, and genitourinary tract, and is one of the major regulators of kidney development. Mutations in this gene are associated with papillorenal syndrome (PAPRS), a genetic condition characterized by optic nerve dysplasia and renal hypo/dysplasia. In the last 28 years, many cohort studies and case reports highlighted PAX2's involvement in a large spectrum of kidney malformations and diseases, with or without eye abnormalities, defining the phenotypes associated with PAX2 variants as "PAX2-related disorders". Here, we reported two new sequence variations and reviewed PAX2 mutations annotated on the Leiden Open Variation Database 3.0. DNA was extracted from the peripheral blood of 53 pediatric patients with congenital abnormalities of the kidney and urinary tract (CAKUT). PAX2 gene-coding exonic and flanking intronic regions were sequenced with Sanger technology. Two unrelated patients and two twins carrying one known and two unknown PAX2 variations were observed. The frequency of PAX2-related disorders in this cohort was 5.8%, considering all CAKUT phenotypes (16.7% in the PAPRS phenotype and 2.5% in non-syndromic CAKUT). Although PAX2 mutations have a higher frequency in patients with PAPRS or non-syndromic renal hypoplasia, from the review of variants reported to date in LOVD3, PAX2-related disorders are detected in pediatric patients with other CAKUT phenotypes. In our study, only one patient had a CAKUT without an ocular phenotype, but his twin had both renal and ocular involvement, confirming the extreme inter- and intrafamilial phenotypic variability.

Bim Expression Modulates Branching Morphogenesis of the Epithelium and Endothelium.

Branching morphogenesis is a key developmental process during organogenesis, such that its disruption frequently leads to long-term consequences. The kidney and eye share many etiologies, perhaps, due to similar use of developmental branching morphogenesis and signaling pathways including cell death. Tipping the apoptotic balance towards apoptosis imparts a ureteric bud and retinal vascular branching phenotype similar to one that occurs in papillorenal syndrome. Here, to compare ureteric bud and retinal vascular branching in the context of decreased apoptosis, we investigated the impact of Bim, Bcl-2’s rival force. In the metanephros, lack of Bim expression enhanced ureteric bud branching with increases in ureteric bud length, branch points, and branch end points. Unfortunately, enhanced ureteric bud branching also came with increased branching defects and other undesirable consequences. Although we did see increased nephron number and renal mass, we observed glomeruli collapse. Retinal vascular branching in the absence of Bim expression had similarities with the ureteric bud including increased vascular length, branching length, segment length, and branching interval. Thus, our studies emphasize the impact appropriate Bim expression has on the overall length and branching in both the ureteric bud and retinal vasculature.

De Novo PAX2 Mutation With Associated Papillorenal Syndrome: A Case Report and Literature Review of Penetrance and Expressivity

We report the ocular findings of a Caucasian female with papillorenal syndrome (PAPRS) from a de novo PAX2 mutation. She presented to our clinic with early-onset end-stage renal disease. Ophthalmologic exam revealed bilateral band keratopathy, abnormal optic disc configuration, and Elschnig spots, with preserved visual acuity. Genomic sequencing revealed a heterozygous nonsense PAX2 mutation (C > G p. (Tyr73*) at position 219 in exon 3) associated with PAPRS. Parents of the proband did not display phenotypic features of PAPRS and were confirmed to be without the PAX2 mutation.

Vitrectomy for Retinoschisis in Papillorenal Syndrome Related to PAX2 Mutation

A 36-year-old woman with a history of kidney transplantation presented with visual disturbance in the right eye. Optic disc excavation, absence of central retinal vessels, numerous cilioretinal vessels in both eyes, and macular thickening were noted in the right eye (Fig A and B). A PAX2 mutation was confirmed by genetic testing. OCT showed schisis of the outer plexiform and nerve fiber layers and foveal detachment with outer macular hole (Fig C). The patient underwent vitrectomy with gas tamponade.

Neonate with Respiratory Distress, Bilateral Microtia, Hypocalcemia, and Lymphopenia.

Neonate with Respiratory Distress, Bilateral Microtia, Hypocalcemia, and Lymphopenia.

Phenotypic spectrum and genetics of PAX2-related disorder in the Chinese cohort

BackgroundPathogenic variants of PAX2 cause autosomal-dominant PAX2-related disorder, which includes variable phenotypes ranging from renal coloboma syndrome (RCS), congenital anomalies of the kidney and urinary tract (CAKUT) to nephrosis. Phenotypic variability makes it difficult to define the phenotypic spectrum associated with genotype.MethodsWe collected the phenotypes in patients enrolled in the China national multicenter registry who were diagnosed with pathogenic variant in PAX2 and reviewed all published cases with PAX2-related disorders. We conducted a phenotype-based cluster analysis by variant types and molecular modeling of the structural impact of missense variants.ResultsTwenty different PAX2 pathogenic variants were identified in 32 individuals (27 families) with a diagnosis of RCS (9), CAKUT (11) and nephrosis (12) from the Chinese cohort. Individuals with abnormal kidney structure (RCS or CAKUT group) tended to have likely/presumed gene disruptive (LGD) variants (Fisher test, p < 0.05). A system review of 234 reported cases to date indicated a clear association of RCS to heterozygous loss-of-function PAX2 variants (LGD variants). Furthermore, we identified a subset of PAX2 missense variants in DNA-binding domain predicted to affect the protein structure or protein-DNA interaction associated with the phenotype of RCS.ConclusionDefining the phenotypic spectrum combined with genotype in PAX2-related disorder allows us to predict the pathogenic variants associated with renal and ophthalmological development. It highlighted the approach of structure-based analysis can be applied to diagnostic strategy aiding precise and timely diagnosis.

Resolving severe oligohydramnios as an early prenatal presentation of renal coloboma syndrome—A report of two generations

This report suggests that self‐resolving oligohydramnios is an early sign of malfunctioning kidney in individuals with renal coloboma syndrome (RCS) and demonstrates how a genetic diagnosis can impact patient and fetal management as it outlines two generations of RCS.

Ultra-rare renal diseases diagnosed with whole-exome sequencing: Utility in diagnosis and management

BackgroundThis study aimed to use whole-exome sequencing (WES) to diagnose ultra-rare renal diseases and the clinical impact of such an approach on patient care.MethodsClinical, radiological, pathological, and genetic findings were reviewed in the patients and their family members.ResultsNine patients from nine unrelated Korean families were included in the study and evaluated. WES identified eight different conditions in these patients, i.e., autosomal dominant tubulointerstitial kidney disease associated with UMOD mutation; recurrent urinary stones associated with APRT deficiency; Ayme-Gripp syndrome associated with MAF mutation; short rib-thoracic dysplasia associated with IFT140 mutation; renal coloboma syndrome associated with PAX2 mutations; idiopathic infantile hypercalcemia associated with CYP24A1 mutation; and hypomagnesemia associated with TRPM mutation. Eleven different mutations, including seven novel mutations, were identified, i.e., four truncating mutations, six missense mutations, and one splice-acceptor variant. After genetic confirmation, strategies for the management of the following: medications, donor selection for renal transplantation, and surveillance for extra-renal manifestations were altered. In addition, genetic counseling was provided for the patients and their family members with respect to family member screening for affected but yet unidentified patients and future reproductive planning.ConclusionAs WES can effectively identify ultra-rare genetic renal diseases, facilitate the diagnosis process, and improve patient care, it is a good approach to enable a better understanding of ultra-rare conditions and for the establishment of appropriate counseling, surveillance, and management strategies.

Identification of candidate PAX2-regulated genes implicated in human kidney development

PAX2 is a transcription factor essential for kidney development and the main causative gene for renal coloboma syndrome (RCS). The mechanisms of PAX2 action during kidney development have been evaluated in mice but not in humans. This is a critical gap in knowledge since important differences have been reported in kidney development in the two species. In the present study, we hypothesized that key human PAX2-dependent kidney development genes are differentially expressed in nephron progenitor cells from induced pluripotent stem cells (iPSCs) in patients with RCS relative to healthy individuals. Cap analysis of gene expression revealed 189 candidate promoters and 71 candidate enhancers that were differentially activated by PAX2 in this system in three patients with RCS with PAX2 mutations. By comparing this list with the list of candidate Pax2-regulated mouse kidney development genes obtained from the Functional Annotation of the Mouse/Mammalian (FANTOM) database, we prioritized 17 genes. Furthermore, we ranked three genes—PBX1, POSTN, and ITGA9—as the top candidates based on closely aligned expression kinetics with PAX2 in the iPSC culture system and susceptibility to suppression by a Pax2 inhibitor in cultured mouse embryonic kidney explants. Identification of these genes may provide important information to clarify the pathogenesis of RCS, human kidney development, and kidney regeneration.

Optic Disc Anomalies with Anomalous Disc Size

Optic disc anomalies are etiologically divided into two categories: congenital and acquired. Congenital optic disc anomalies are usually diagnosed with the appearance of the optic disc and anomalies in the retina surrounding it. As a general rule, these anomalies are classified according to optic disc size, conformation, and the presence of abnormal tissue in the optic nerve head. In our study, optic nerve anomalies with abnormal disc size (congenital tilted disc syndrome, optic nerve hypoplasia, segmental optic nerve hypoplasia, homonymous hemioptic hypoplasia, optic disc dysplasia, papillorenal syndrome, and megalopapilla) are discussed. Visual acuity decrease or loss is often seen in these anomalies, increasing the clinical importance of the diseases. In addition, since congenital optic disc anomalies with abnormal disc size may be a part of an isolated or systemic malformation; early diagnosis and treatment gain importance to improve visual acuity if possible, if not, to optimize, and to evaluate other accompanying ocular and systemic disorders. A multidisciplinary approach is required for the diagnosis and follow-up of neurological, endocrinological, and renal anomalies in children with optic nerve anomalies. When deemed necessary, the clinician should not hesitate to cooperate with the relevant departments or direct the patient to centers where a more inclusive health service can be obtained.

Renal oligohydramnios and Potter sequence with cystic kidney disease

For the first time in 1946 E.L. Potter (1901–1993) described the characteristic appearance of stillborns and deceased newborns with bilateral renal agenesis. Due to the further observations Potter distinguished the syndrome (Q60.6) – a set of characteristic external signs that are formed due to the extreme degree of oligohydramnios and intrauterine compression of the fetus. Classical Potter syndrome is diagnosed by the disfunction of both kidneys in the fetus (for example, bilateral agenesis), which leads to death. The term «Potter sequence» or oligohydramnios sequence with diverse causes has received the wide clinical use. The term «renal oligohydramnios» (ROH) is used to describe oligohydramnios resulting from a decrease or absence of fetal kidney function. The authors state that renal oligohydramnios and Potter sequence often develop in the fetus with cystic kidney disease with the formation of cysts in the parenchyma of both kidneys (autosomal recessive polycystic kidney disease, autosomal dominant polycystic kidney disease, glomerulocystic kidney disease associated with HNF1ß/TCF2 gene mutations, renal-coloboma syndrome, cystic renal hypoplasia, cystic renal dysplasia with mutations of the CEP55 gene).

Bilateral Morning Glory Anomaly With Optic Nerve Multiple Cysts

We herein describe a pediatric case of bilateral morning glory anomaly whose retrobulbar cysts and renal disease were underdiagnosed, and finally, he was diagnosed with renal coloboma syndrome. We recommend patients with colobomatous optic nerve malformations undergo a complete workup to avoid missed diagnosis, which includes (i) general physical examination looking for heart defects, genitourinary, auricular, and midline facial defects among other abnormalities; (ii) simple nephrologic investigations such as routine urine test and/or renal ultrasound to check for renal hypoplasia; and (iii) neuroimaging check for cerebrovascular anomalies and midline cranial defects. Genetic testing can be a useful tool to guide the workup.

Renal coloboma syndrome with epilepsy.

Renal coloboma syndrome with epilepsy.

Analysis of prenatal phenotype and pathogenetic variant in a fetus with Papillorenal syndrome

To determine the carrier rate of deafness-related genetic variants among 53 873 newborns from Zhengzhou. Heel blood samples of the newborns were collected with informed consent from the parents, and 15 loci of 4 genes related to congenital deafness were detected by microarray. In total 2770 newborns were found to carry deafness-related variants, with a carrier rate of 5.142%. 1325 newborns (2.459%) were found to carry heterozygous variants of the GJB2 gene, 1071 (1.988%) were found with SLC26A4 gene variants, 205 were found with GJB3 gene variants (0.381%), and 120 were found with 12S rRNA variants (0.223%). Five newborns have carried homozygous GJB2 variants, two have carried homozygous SLC26A4 variants, five have carried compound heterozygous GJB2 variants, and four have carried compound heterozygous SLC26A4 variants. 33 neonates have carried heterozygous variants of two genes at the same time. The carrier rate of deafness-related variants in Zhengzhou, in a declining order, is for GJB2, SLC26A4, GJB3 and 12S rRNA. The common variants included GJB2 235delC and SLC26A4 IVS7-2A>G, which are similar to other regions in China. To carry out genetic screening of neonatal deafness can help to identify congenital, delayed and drug-induced deafness, and initiate treatment and follow-up as early as possible.