Osteopontin deletion attenuates cyst growth but exacerbates fibrosis in mice with cystic kidney disease.

Osteopontin (OPN) is a multi-functional glycoprotein that coordinates the innate immune response, prevents nanocrystal formation in renal tubule fluid, and is a biomarker for kidney injury. OPN expression is markedly increased in cystic epithelial cells of polycystic kidney disease (PKD) kidneys; however, its role in PKD progression remains unclear. We investigated the in vitro effects of recombinant OPN on the proliferation of tubular epithelial cells from PKD and normal human kidneys and in vivo effects of OPN deletion on kidney cyst formation, fibrosis, and mineral metabolism in pcy/pcy mice, a non-orthologous model of autosomal-dominant PKD. In vitro studies revealed that OPN enhanced the proliferation of PKD cells but had no effect on normal kidney cells. Deletion of OPN in pcy/pcy mice significantly reduced kidney cyst burden; however, this was accompanied by increased fibrosis and no change in kidney function. The loss of OPN had no effect on kidney macrophage numbers, cyst epithelial cell proliferation, or apoptosis. Furthermore, there was no difference in kidney mineral deposition or mineral metabolism parameters between pcy/pcy mice with and without OPN expression. Global deletion of OPN reduced kidney cyst burden, while paradoxically exacerbating kidney fibrosis in mice with cystic kidney disease.

Deficiency of geranylgeranyl biphosphate synthase in kidney tubules causes cystic kidney disease.

Polycystic kidney disease (PKD) is a common hereditary kidney disease. Although PKD occurrence is associated with certain gene mutations, its onset regulatory mechanisms are still not well understood. Here, we first report that the key enzyme geranylgeranyl diphosphate synthase (GGPPS) is specifically expressed in renal tubular epithelial cells of mouse kidneys. We aimed to explore the role of GGPPS in PKD. In this study, we established a Ggppsfl/fl:Cdh16cre mouse model and compared its phenotype with that of wild-type mice. A Ggpps-downregulation HK2 cell model was also used to further determine the role of GGPPS. We found that GGPPS was specifically expressed in renal tubular epithelial cells of mouse kidneys. Its expression also increased with age. Low GGPPS expression was observed in human ADPKD tissues. In the Ggppsfl/fl:Cdh16cre mouse model, Ggpps deletion in renal tubular epithelial cells induced the occurrence and development of renal tubule cystic dilation and caused the death of mice after birth due to abnormal renal function. Enhanced proliferation of cyst-lining epithelial cells was also observed after the knockout of Ggpps. These processes were related to the increased rate of Rheb on membrane/cytoplasm and hyperactivation of mTORC1 signaling. In conclusion, the deficiency of GGPPS in kidney tubules induced the formation of renal cysts. It may play a critical role in PKD pathophysiology. A novel therapeutic strategy could be designed according to this work.

[Identification of TCTN1 gene variants in a fetus with Joubert syndrome 13].

OBJECTIVE: To explore the clinical characteristics and genetic basis for a fetus with Joubert syndrome. METHODS: A pregnant woman who had visited Suzhou Municipal Hospital on February 26, 2021 was selected as the study subject. The fetus and her parents were subjected to whole exome sequencing (WES), and candidate variants were verified by Sanger sequencing. cDNA analysis of her father and RNA sequencing of her sister were also carried out. RESULTS: The fetus was found to harbor compound heterozygous variants of the TCTN1 gene, namely c.624G>A and c.96dupA (p.Glu33Argfs*49), which were inherited from her father and mother, respectively. Her sister also carried the paternal c.624G>A variant, and mRNA transcripts with the c.624G>A variant of the TCTN1 gene were not detected by cDNA analysis of her father and RNA sequencing of her sister. Based on the guidelines from the American College of Medical Genetics and Genomics (ACMG), the c.624G>A and c.96dupA variants were both classified as likely pathogenic (PVS1+PM2_Supporting). CONCLUSION: The compound heterozygous variants of the TCTN1 gene probably underlay the pathogenesis in this fetus. Above finding has also expanded the mutational spectrum of the TCTN1 gene.

Developmental, Cognitive, Ocular Motor, and Neuroimaging Findings Related to SUFU Haploinsufficiency: Unraveling Subtle and Highly Variable Phenotypes.

BACKGROUND: Biallelic SUFU variants have originally been linked to Joubert syndrome, comprising cerebellar abnormalities, dysmorphism, and polydactyly. In contrast, heterozygous truncating variants have recently been associated with developmental delay and ocular motor apraxia, but only a limited number of patients have been reported. Here, we aim to delineate further the mild end of the phenotypic spectrum related to SUFU haploinsufficiency. METHODS: Nine individuals (from three unrelated families) harboring truncating SUFU variants were investigated, including two previously reported individuals (from one family). We provide results from a comprehensive assessment comprising neuroimaging, neuropsychology, video-oculography, and genetic testing. RESULTS: We identified three inherited or de novo truncating variants in SUFU (NM_016169.4): c.895C>T p.(Arg299∗), c.71dup p.(Ala25Glyfs∗23), and c.71del p.(Pro24Argfs∗72). The phenotypic expression showed high variability both between and within families. Clinical features include motor developmental delay (seven of nine), axial hypotonia (five of nine), ocular motor apraxia (three of nine), and cerebellar signs (three of nine). Four of the six reported children had macrocephaly. Neuropsychological and developmental assessments revealed mildly delayed language development in the youngest children, whereas general cognition was normal in all variant carriers. Subtle but characteristic SUFU-related neuroimaging abnormalities (including superior cerebellar dysplasia, abnormalities of the superior cerebellar peduncles, rostrally displaced fastigium, and vermis hypoplasia) were observed in seven of nine individuals. CONCLUSIONS: Our data shed further light on the mild but recognizable features of SUFU haploinsufficiency and underline its marked phenotypic variability, even within families. Notably, neurodevelopmental and behavioral abnormalities are mild compared with Joubert syndrome and seem to be well compensated over time.

Expanding the phenotypic spectrum of CC2D2A-related ciliopathies: a rare homozygous nonsense variant in a patient with suspected nephronophthisis.

Biallelic pathogenic variants in the gene CC2D2A cause a spectrum of ciliopathies, including Joubert and Meckel syndrome, which frequently involve the kidney; however, no cases of isolated renal disease (i.e., nephronophthisis) have yet been reported. In an adult with a clinical presentation consistent with nephronophthisis, next-generation sequencing identified a rare homozygous nonsense variant in CC2D2A (c.100 C > T; p.(Arg34*)). Tissue-specific expression data and promoter activity analysis demonstrates that this variant primarily affects a transcript isoform predominant in the kidneys but does not affect the transcript isoforms predominant in other tissues typically involved in CC2D2A-related ciliopathies (e.g., cerebellum, liver). Expression analysis of patient-specific cDNA in MDCK cells demonstrates partial translation re-initiation downstream of p.(Arg34*) as a possible escape mechanism from nonsense mediated decay. These data provide mechanistic insights in support of this novel genotype-phenotype association.

[The application value of whole exome sequencing technology in diagnosis of hereditary renal cysts].

The data of 57 renal cyst patients who visited the First Affiliated Hospital of Zhengzhou University from January 2023 to March 2024 were retrospectively analyzed. The age of patients ranged from three months to 60 years old, with 31 males and 26 females. The whole exome sequencing (WES) detected pathogenic or suspected pathogenic (P/LP) variants in 48 renal cystic probands, with a detection rate of 84.2% (48/57), including PKD1, PKD2, PKHD1, LRP5, COL4A4 and ALG8 gene variants as well as copy number variations (CNV). In addition, four PKD1 gene variants of uncertain significance (VUS) were detected. In five WES negative families, one PKD1 nonsense variation was detected through long-range PCR (LR-PCR)+Oxford nanopore technologies, and one heterozygous deletion in exon 22 of PKD1 gene was detected through multiplex ligation-dependent probe amplification (MLPA). In summary, WES can detect multiple types of variations, which is helpful for early diagnosis and prognosis prediction of renal cyst patients. However, there is still a risk of failing to detect PKD1 gene by WES, therefore, healthcare practitioners should beware of the negative results of WES.

Case report of a child with nephronophthisis from South Africa.

BACKGROUND: Nephronophthisis (NPHP) is an autosomal recessive disorder with a subset of patients presenting with extrarenal manifestations such as retinal degeneration, cerebella ataxia, liver fibrosis, skeletal abnormalities, cardiac malformations, and lung bronchiectasis. However, the involvement of other organ systems has also been documented. Extrarenal manifestations occur in approximately 10-20% of patients. In developed countries, it has been reported as one of the most common causes of monogenic chronic kidney failure (CKF) during the first three decades of life, with more than 25 genes associated with this condition. The current treatment options for managing NPHP include supportive care, management of complications, and kidney replacement therapy when necessary. The index patient is a 10-year-old Caucasian female who presented with recurrent attacks of abdominal pain. Her elder sister, TN, who was 17 years old, was diagnosed with CKF and noted to have persistently elevated liver enzymes (gamma-glutamyl transferase, alanine, and aspartate transaminases). Following genetic testing, her elder sister was shown to have Nephronophthisis Type 3, and a liver biopsy showed early fibrotic changes. Subsequent genetic testing confirmed the index patient as having NPHP Type 3. A kidney biopsy showed focal sclerosed glomeruli with patchy areas of tubular atrophy and related tubulointerstitial changes in keeping with NPHP. We present the first confirmatory case of NPHP from South Africa based on histopathology and genetic testing in a 10-year-old Caucasian female who presented with recurrent attacks of abdominal pain, whose elder sister also presented with CKF and early liver fibrosis, confirmed on biopsy and genetic testing. CONCLUSION: In low-middle-income countries, genetic testing should be undertaken whenever possible to confirm the diagnosis of NPHP, especially in those with a suggestive biopsy or if there is CKF of unknown aetiology with or without extra-renal manifestations.

Expanding the Phenotypic Spectrum of Pathogenic KIAA0586 Variants: From Joubert Syndrome to Hydrolethalus Syndrome.

KIAA0586 variants have been associated with a wide range of ciliopathies, mainly Joubert syndrome (JS, OMIM #616490) and short-rib thoracic dysplasia syndrome (SRTD, OMIM #616546). However, the hypothesis that this gene is involved with hydrolethalus syndrome (HSL, OMIM #614120) and orofaciodigital syndrome IV (OMIM #258860) has already been raised. Ciliopathies' clinical features are often overlapped despite differing in phenotype severity. Besides KIAA0586, HYLS1 and KIF7 are also known for being causative of ciliopathies, indicating that all three genes may have similar or converging genomic pathways. Overall, the genotypic and phenotypic spectrum of ciliopathies becomes wider and conflicting while more and more new variants are added to this group of disorders' molecular pot. In this case report we discuss the first Brazilian individual clinically diagnosed with hydrolethalus syndrome and molecular findings that demonstrate the role of KIAA0586 as a causative gene of a group of genetic disorders. Also, recent reports on individuals with intronic and exonic variants combined leading to ciliopathies support our patient's molecular diagnosis. At the same time, we discuss variable expressivity and overlapping features in ciliopathies.

Primary cilia formation requires the Leigh syndrome-associated mitochondrial protein NDUFAF2.

Mitochondria-related neurodegenerative diseases have been implicated in the disruption of primary cilia function. Mutation in an intrinsic mitochondrial complex I component NDUFAF2 has been identified in Leigh syndrome, a severe inherited mitochondriopathy. Mutations in ARMC9, which encodes a basal body protein, cause Joubert syndrome, a ciliopathy with defects in the brain, kidney, and eye. Here, we report a mechanistic link between mitochondria metabolism and primary cilia signaling. We discovered that loss of NDUFAF2 caused both mitochondrial and ciliary defects in vitro and in vivo and identified NDUFAF2 as a binding partner for ARMC9. We also found that NDUFAF2 was both necessary and sufficient for cilia formation and that exogenous expression of NDUFAF2 rescued the ciliary and mitochondrial defects observed in cells from patients with known ARMC9 deficiency. NAD+ supplementation restored mitochondrial and ciliary dysfunction in ARMC9-deficient cells and zebrafish and ameliorated the ocular motility and motor deficits of a patient with ARMC9 deficiency. The present results provide a compelling mechanistic link, supported by evidence from human studies, between primary cilia and mitochondrial signaling. Importantly, our findings have significant implications for the development of therapeutic approaches targeting ciliopathies.

Genetic and radiological aspects of pediatric renal cystic disease: A case series / Aspectos genéticos e imagenológicos de la enfermedad quística renal en pediatría: serie de casos

Renal cystic diseases are common conditions whose etiology can be highly heterogeneous. They require a correct approach for adequate diagnosis and management. We aimed to illustrate part of the spectrum of renal cystic diseases through some clinical cases managed in our service. We describe 11 clinical cases including clinical entities such as renal multicystic dysplasia, and autosomal dominant and autosomal recessive polycystic renal disease, among other pathologies. Renal cystic diseases are heterogeneous in their clinical presentation, natural history, radiological findings, and genetic and pathophysiological basis. An integral clinical approach is needed to get a clear etiological diagnosis and offer adequate individualized care and follow-up for patients.

Las enfermedades quísticas renales son condiciones frecuentes cuya etiología puede ser muy heterogénea, por lo que se requiere un adecuado abordaje para su diagnóstico y manejo. El objetivo de este trabajo fue ilustrar parte del espectro de la enfermedad renal quística por medio de casos clínicos manejados en la Fundación Valle del Lili. Se describen 11 casos clínicos que incluyen enfermedades como displasia multiquística renal, enfermedad poliquística renal autosómica dominante y autosómica recesiva, entre otras. Las enfermedades quísticas renales varían en su presentación clínica, historia natural, hallazgos imagenológicos, bases genéticas y fisiopatológicas, por consiguiente, el enfoque diagnóstico y el manejo integral se debe realizar de forma individualizada y con un abordaje multidisciplinario.

Identification of a Novel Deletion Variant (c.2999_3005delTGTGTGT/p.Asn1000SerfsTer4) in NPHP4 Associated With Nephronophthisis-4.

BACKGROUND: Nephronophthisis-4 (NPHP4) is an inherited renal ciliopathy described by renal fibrosis and progressive impairment of kidney function. This study aimed to investigate the genetic basis and clinical manifestations of NPHP4 in two Iranian siblings. METHODS: The proband was a 27-year-old male with features of end-stage renal disease, including anemia, uremia, polyuria, and polydipsia. It is worth mentioning that he has a 22-year-old sister with a similar presentation. Clinical diagnosis procedures, such as renal biopsy, brain imaging, blood and urine tests, cardiac evaluation, ophthalmic inspection, and auditory function assessment, were carried out to evaluate organ involvement and potential comorbidities. Whole-exome sequencing (WES) and segregation analysis were performed to identify and confirm genetic variants associated with the condition. Computational variant analysis was conducted to evaluate the pathogenicity of the candidate variant. Furthermore, the SWISS-MODEL server was utilized for protein modeling. RESULTS: The brain, cardiac, ocular, and auditory functions were normal. Renal biopsy of the proband showed chronic interstitial inflammation and fibrosis. We found a novel homozygous 7-base pair deletion (c.2999_3005delTGTGTGT/ p.Asn1000SerfsTer4) in exon 21 of NPHP4 by WES. Segregation analysis confirmed homozygosity for the NPHP4 variant in affected individuals and heterozygous carrier status in parents, supporting autosomal recessive inheritance. 3D protein modeling indicated significant structural changes due to the variant. CONCLUSION: This study expands the genetic causes and phenotypic spectrum of nephronophthisis-4 and reveals the importance of genetic analysis in diagnosing and managing rare inherited kidney disorders, particularly those involving consanguinity.

CEP41, a ciliopathy-linked centrosomal protein, regulates microtubule assembly and cell proliferation.

Centrosomal proteins play pivotal roles in orchestrating microtubule dynamics, and their dysregulation leads to disorders, including cancer and ciliopathies. Understanding the multifaceted roles of centrosomal proteins is vital to comprehend their involvement in disease development. Here, we report novel cellular functions of CEP41, a centrosomal and ciliary protein implicated in Joubert syndrome. We show that CEP41 is an essential microtubule-associated protein with microtubule-stabilizing activity. Purified CEP41 binds to preformed microtubules, promotes microtubule nucleation and suppresses microtubule disassembly. When overexpressed in cultured cells, CEP41 localizes to microtubules and promotes microtubule bundling. Conversely, shRNA-mediated knockdown of CEP41 disrupts the interphase microtubule network and delays microtubule reassembly, emphasizing its role in microtubule organization. Further, we demonstrate that the association of CEP41 with microtubules relies on its conserved rhodanese homology domain (RHOD) and the N-terminal region. Interestingly, a disease-causing mutation in the RHOD domain impairs CEP41-microtubule interaction. Moreover, depletion of CEP41 inhibits cell proliferation and disrupts cell cycle progression, suggesting its potential involvement in cell cycle regulation. These insights into the cellular functions of CEP41 hold promise for unraveling the impact of its mutations in ciliopathies.

Acquired cystic disease associated renal cell carcinoma: A clinicopathologic and molecular study of 31 tumors.

Acquired cystic disease associated renal cell carcinomas (ACD-RCC) are rare and their molecular and histopathological characteristics are still being explored. We therefore investigated the clinicopathologic and molecular characteristics of 31 tumors. The patients were predominantly male (n = 30), with tumors mainly left-sided (n = 17), unifocal (n = 19), and unilateral (n = 29) and a mean tumor size of 25 mm (range, 3-65 mm). Microscopically, several histologic patterns were present, including pure classic sieve-like (n = 4), and varied proportions of mixed classic sieve-like with papillary (n = 23), tubulocystic (n = 9), compact tubular (n = 4) and solid (n = 1) patterns. Calcium-oxalate crystals were seen in all tumors. Molecular analysis of 9 tumors using next generation sequencing showed alterations in SMARCB1 in 3 tumors (1 with frameshift deletion and 2 with copy number loss in chromosome 22 involving SMARCB1 region), however, INI1 stain was retained in all. Nonrecurrent genetic alterations in SETD2, NF1, NOTCH4, BRCA2 and CANT1 genes were also seen. Additionally, MTOR p.Pro351Ser was identified in one tumor. Copy number analysis showed gains in chromosome 16 (n = 5), 17 (n = 2) and 8 (n = 2) as well as loss in chromosome 22 (n = 2). In summary, ACD-RCC is a recognized subtype of kidney tumors, with several histological architectural patterns. Our molecular data identifies genetic alterations in chromatin modifying genes (SMARCB1 and SETD2), which may suggest a role of such genes in ACD-RCC development.

Defects in diffusion barrier function of ciliary transition zone caused by ciliopathy variations of TMEM218.

Primary cilia are antenna-like structures protruding from the surface of various eukaryotic cells, and have distinct protein compositions in their membranes. This distinct protein composition is maintained by the presence of the transition zone (TZ) at the ciliary base, which acts as a diffusion barrier between the ciliary and plasma membranes. Defects in cilia and the TZ are known to cause a group of disorders collectively called the ciliopathies, which demonstrate a broad spectrum of clinical features, such as perinatally lethal Meckel syndrome (MKS), relatively mild Joubert syndrome (JBTS), and nonsyndromic nephronophthisis (NPHP). Proteins constituting the TZ can be grouped into the MKS and NPHP modules. The MKS module is composed of several transmembrane proteins and three soluble proteins. TMEM218 was recently reported to be mutated in individuals diagnosed as MKS and JBTS. However, little is known about how TMEM218 mutations found in MKS and JBTS affect the functions of cilia. In this study, we found that ciliary membrane proteins were not localized to cilia in TMEM218-knockout cells, indicating impaired barrier function of the TZ. Furthermore, the exogenous expression of JBTS-associated TMEM218 variants but not MKS-associated variants in TMEM218-knockout cells restored the localization of ciliary membrane proteins. In particular, when expressed in TMEM218-knockout cells, the TMEM218(R115H) variant found in JBTS was able to restore the barrier function of cells, whereas the MKS variant TMEM218(R115C) could not. Thus, the severity of symptoms of MKS and JBTS individuals appears to correlate with the degree of their ciliary defects at the cellular level.

Carbonic Anhydrase 2 Deletion Delays the Growth of Kidney Cysts Whereas Foxi1 Deletion Completely Abrogates Cystogenesis in TSC.

Tuberous sclerosis complex (TSC) presents with renal cysts and benign tumors, which eventually lead to kidney failure. The factors promoting kidney cyst formation in TSC are poorly understood. Inactivation of carbonic anhydrase 2 (Car2) significantly reduced, whereas, deletion of Foxi1 completely abrogated the cyst burden in Tsc1 KO mice. In these studies, we contrasted the ontogeny of cyst burden in Tsc1/Car2 dKO mice vs. Tsc1/Foxi1 dKO mice. Compared to Tsc1 KO, the Tsc1/Car2 dKO mice showed few small cysts at 47 days of age. However, by 110 days, the kidneys showed frequent and large cysts with overwhelming numbers of A-intercalated cells in their linings. The magnitude of cyst burden in Tsc1/Car2 dKO mice correlated with the expression levels of Foxi1 and was proportional to mTORC1 activation. This is in stark contrast to Tsc1/Foxi1 dKO mice, which showed a remarkable absence of kidney cysts at both 47 and 110 days of age. RNA-seq data pointed to profound upregulation of Foxi1 and kidney-collecting duct-specific H+-ATPase subunits in 110-day-old Tsc1/Car2 dKO mice. We conclude that Car2 inactivation temporarily decreases the kidney cyst burden in Tsc1 KO mice but the cysts increase with advancing age, along with enhanced Foxi1 expression.

Variable phenotype and genotype of pediatric patients with HNF1B nephropathy.

AIMS: Hepatocyte nuclear factor 1ß (HNF1B) mutations are the most common monogenic cause of congenital anomalies of the kidney and urinary tract (CAKUT). We aimed to investigate clinical and genetic characteristics of patients with HNF1B nephropathy to expand its phenotypic and genetic spectrum. MATERIALS AND METHODS: This retrospective cohort study included 16 unrelated pediatric patients (6 females, 10 males) from 13 families with genetically confirmed HNF1B-related nephropathy. RESULTS: Abnormal prenatal kidney abnormalities were present in 13 patients (81.3%). The most common antenatal kidney abnormality was kidney cysts, which were observed in 8 patients (61.5%). Urinary system abnormalities (vesicoureteral reflux (VUR) and ureteropelvic junction obstruction (UPJO)) were present in 4 patients (25%). HNF1B analysis uncovered missense variants in 4 families (30.8%) as the most common genetic abnormality. In addition, 4 novel pathological variations have been defined. During follow-up, hypomagnesemia and hyperuricemia were observed in 7 (43.8%) and 5 patients (31.3%), respectively. None of the patients with a missense variant had hypomagnesemia. However, 7 out of 12 patients (58.3%) with a non-missense variant had hypomagnesemia (p = 0.09). None of the patients had an HNF1B score below 8, and the mean score was 15.3 ± 4.4. The mean follow-up period was 7.4 ± 5.0 years. While 100% of patients (n = 4) with missense variants were in various stages of CKD (CKD2: 2 patients, CKD3: 2 patients), 25% of those with non-missense variants had CKD (CKD2, 3, and 5; 1 patient, respectively) (p = 0.026). CONCLUSION: Patients with HNF1B-associated disease have concomitant urinary system abnormalities such as VUR or UPJO. Missense variants seem to be the most common pathological variations in HNF1B gene and have higher risk of CKD.

Joubert syndrome presenting bilateral peroneal neuropathies: A case report.

RATIONALE: Joubert syndrome (JS) is a rare genetic disorder that presents with various neurological symptoms, primarily involving central nervous system dysfunction. Considering the etiology of JS, peripheral nervous system abnormalities cannot be excluded; however, cases of JS accompanied by peripheral nervous system abnormalities have not yet been reported. Distinct radiological findings on brain magnetic resonance imaging were considered essential for the diagnosis of JS. However, recently, cases of JS with normal or nearly normal brain morphology have been reported. To date, there is no consensus on the most appropriate diagnostic method for JS when imaging-based diagnostic approach is challenging. This report describes the case of an adult patient who exhibited bilateral peroneal neuropathies and was finally diagnosed with JS through genetic testing. PATIENT CONCERNS AND DIAGNOSIS: A 27-year-old man visited our outpatient clinic due to a gait disturbance that started at a very young age. The patient exhibited difficulty maintaining balance, especially when walking slowly. Oculomotor apraxia was observed on ophthalmic evaluation. During diagnostic workups, including brain imaging and direct DNA sequencing, no conclusive findings were detected. Only nerve conduction studies revealed profound bilateral peroneal neuropathies. We performed whole genome sequencing to obtain a proper diagnosis and identify the gene mutation responsible for JS. LESSONS: This case represents the first instance of peripheral nerve dysfunction in JS. Further research is needed to explore the association between JS and peripheral nervous system abnormalities. Detailed genetic testing may serve as a valuable tool for diagnosing JS when no prominent abnormalities are detected in brain imaging studies.

The Phenotypic Variability Associated with Hepatocyte Nuclear Factor 1B Genetic Defects Poses Challenges in Both Diagnosis and Therapy.

The evolving landscape of clinical genetics is becoming increasingly relevant in the field of nephrology. HNF1B-associated renal disease presents with a diverse array of renal and extrarenal manifestations, prominently featuring cystic kidney disease and diabetes mellitus. For the genetic analyses, whole exome sequencing (WES) and multiplex ligation-dependent probe amplification (MLPA) were performed. Bioinformatics analysis was performed with Ingenuity Clinical Insights software (Qiagen). The patient's electronic record was utilized after receiving informed consent. In this report, we present seven cases of HNF1B-associated kidney disease, each featuring distinct genetic abnormalities and displaying diverse extrarenal manifestations. Over 12 years, the mean decline in eGFR averaged -2.22 ± 0.7 mL/min/1.73 m2. Diabetes mellitus was present in five patients, kidney dysplastic lesions in six patients, pancreatic dysplasia, hypomagnesemia and abnormal liver function tests in three patients each. This case series emphasizes the phenotypic variability and the fast decline in kidney function associated with HNF-1B-related disease. Additionally, it underscores that complex clinical presentations may have a retrospectively straightforward explanation through the use of diverse genetic analytical tools.