Genetic or hereditary kidney disease stands as a pivotal cause of chronic kidney disease (CKD). The proliferation and widespread utilization of DNA testing in clinical settings have notably eased the diagnosis of genetic kidney diseases, which were once elusive but are now increasingly identified in cases previously deemed CKD of unknown etiology. However, despite these diagnostic strides, research into disease pathogenesis and novel drug development faces significant hurdles, chiefly due to the dearth of appropriate animal models and the challenges posed by limited patient cohorts in clinical studies. Conversely, the advent and utilization of human-induced pluripotent stem cells (hiPSCs) offer a promising avenue for genetic kidney disease research. Particularly, the development of hiPSC-derived kidney organoid systems presents a novel platform for investigating various forms of genetic kidney diseases. Moreover, the integration of the CRISPR/Cas9 technique into this system holds immense potential for efficient research on genetic kidney diseases. This review aims to explore the applications of in vitro kidney organoids generated from hiPSCs in the study of diverse genetic kidney diseases. Additionally, it will delve into the limitations of this research platform and outline future perspectives for advancing research in this crucial area.

Vascular calcification is prevalent in chronic kidney disease (CKD). Genetic causes of CKD account for 10-20% of adult-onset disease. Vascular calcification is thought to be one of the most important risk factors for increased cardiovascular morbidity and mortality in CKD patients and is detectable in 80% of patients with end stage kidney disease (ESKD). Despite the high prevalence of vascular calcification in CKD, no single gene cause has been described. We hypothesized that variants in vascular calcification genes may contribute to disease pathogenesis in CKD, particularly in families who exhibit a predominant vascular calcification phenotype. We developed a list of eight genes that are hypothesized to play a role in vascular calcification due to their involvement in the ectopic calcification pathway: ABCC6, ALPL, ANK1, ENPP1, NT5E, SLC29A1, SLC20A2, and S100A12. With this, we assessed exome data from 77 CKD patients, who remained unsolved following evaluation for all known monogenic causes of CKD. We also analyzed an independent cohort (Ontario Neurodegenerative Disease Research Initiative (ONDRI), n = 520) who were screened for variants in ABCC6 and compared this to a control cohort of healthy adults (n = 52). We identified two CKD families with heterozygous pathogenic variants (R1141X and A667fs) in ABCC6. We identified 10 participants from the ONDRI cohort with heterozygous pathogenic or likely pathogenic variant in ABCC6. Replication in a healthy control cohort did not reveal any variants. Our study provides preliminary data supporting the hypothesis that ABCC6 may play a role in vascular calcification in CKD. By screening CKD patients for genetic causes early in the diagnostic pathway, patients with genetic causes associated with vascular calcification can potentially be preventatively treated with new therapeutics with aims to decrease mortality.

Genome editing technologies, clustered regularly interspaced short palindromic repeats (CRISPR)-Cas in particular, have revolutionized the field of genetic engineering, providing promising avenues for treating various genetic diseases. Chronic kidney disease (CKD), a significant health concern affecting millions of individuals worldwide, can arise from either monogenic or polygenic mutations. With recent advancements in genomic sequencing, valuable insights into disease-causing mutations can be obtained, allowing for the development of new treatments for these genetic disorders. CRISPR-based treatments have emerged as potential therapies, especially for monogenic diseases, offering the ability to correct mutations and eliminate disease phenotypes. Innovations in genome editing have led to enhanced efficiency, specificity and ease of use, surpassing earlier editing tools such as zinc-finger nucleases and transcription activator-like effector nucleases (TALENs). Two prominent advancements in CRISPR-based gene editing are prime editing and base editing. Prime editing allows precise and efficient genome modifications without inducing double-stranded DNA breaks (DSBs), while base editing enables targeted changes to individual nucleotides in both RNA and DNA, promising disease correction in the absence of DSBs. These technologies have the potential to treat genetic kidney diseases through specific correction of disease-causing mutations, such as somatic mutations in PKD1 and PKD2 for polycystic kidney disease; NPHS1, NPHS2 and TRPC6 for focal segmental glomerulosclerosis; COL4A3, COL4A4 and COL4A5 for Alport syndrome; SLC3A1 and SLC7A9 for cystinuria and even VHL for renal cell carcinoma. Apart from editing the DNA sequence, CRISPR-mediated epigenome editing offers a cost-effective method for targeted treatment providing new avenues for therapeutic development, given that epigenetic modifications are associated with the development of various kidney disorders. However, there are challenges to overcome, including developing efficient delivery methods, improving safety and reducing off-target effects. Efforts to improve CRISPR-Cas technologies involve optimizing delivery vectors, employing viral and non-viral approaches and minimizing immunogenicity. With research in animal models providing promising results in rescuing the expression of wild-type podocin in mouse models of nephrotic syndrome and successful clinical trials in the early stages of various disorders, including cancer immunotherapy, there is hope for successful translation of genome editing to kidney diseases.

UNASSIGNED: In pregnancy-related atypical hemolytic uremic syndrome (p-aHUS), transferring recommendations for treatment decisions from nonpregnant cohorts with thrombotic microangiopathy (TMA) is difficult. Although potential causes of p-aHUS may be unrelated to inherent complement defects, peripartal complications such as postpartum hemorrhage (PPH) or (pre)eclampsia or Hemolysis, Elevated Liver enzymes and Low Platelets (HELLP) syndrome may be unrecognized drivers of complement activation.
UNASSIGNED: To evaluate diagnostic and therapeutic decisions in the practical real-life setting, we conducted an analysis of a cohort of 40 patients from 3 German academic hospitals with a diagnosis of p-aHUS, stratified by the presence (n = 25) or absence (n = 15) of PPH.
UNASSIGNED: Histological signs of TMA were observed in 84.2% of all patients (100% vs. 72.7% in patients without or with PPH, respectively). Patients without PPH had a higher likelihood (20% vs. 0%) of pathogenic genetic abnormalities in the complement system although notably less than in other published cohorts. Four of 5 patients with observed renal cortical necrosis (RCN) after PPH received complement inhibition and experienced partially recovered kidney function. Patients on complement inhibition with or without PPH had an increased need for kidney replacement therapy (KRT) and plasma exchange (PEX). Because renal recovery was comparable among all patients treated with complement inhibition, a potential beneficial effect in this group of pregnancy-associated TMAs and p-aHUS is presumed.
UNASSIGNED: Based on our findings, we suggest a pragmatic approach toward limited and short-term anticomplement therapy for patients with a clinical diagnosis of p-aHUS, which should be stopped once causes of TMA other than genetic complement abnormalities emerge.

UNASSIGNED: Autosomal dominant polycystic kidney disease (ADPKD) affects health-related quality of life (HRQoL) including pain, discomfort, fatigue, emotional distress, and impaired mobility. Stakeholders prioritized kidney cyst-related pain as an important core outcome domain in clinical trials, leading to the development of disease-specific assessment tools.
UNASSIGNED: The ADPKD Registry is hosted online with multiple disease-specific patient-reported outcomes modules to characterize the patient experience in the United States.
UNASSIGNED: The ADPKD Registry allows consented participants access to a Core Questionnaire that includes demographics, comorbid conditions, current symptoms, and kidney function. Participants complete subsequent modules on a 3-month schedule, including 2 validated HRQoL tools, the ADPKD-Pain and Discomfort Scale (ADPKD-PDS), the ADPKD Impact Scale (ADPKD-IS) and a Healthcare Access and Utilization module.
UNASSIGNED: Patient-reported latest estimated glomerular filtration rate or creatinine used to calculate stage of chronic kidney disease.
UNASSIGNED: Health-related quality of life, measured using validated ADPKD-specific tools; access to polycystic kidney disease-specific health care.
UNASSIGNED: For the 2 HRQoL tools, scores were calculated for physical, emotional, and fatigue domains; pain severity; and pain interference (based on the licensed user manuals). Associations to health care access were also assessed.
UNASSIGNED: By July 2022, 1,086 individuals with ADPKD completed at least 1 of the HRQoL modules, and 319 completed 4 over a year. Participants were an average age of 53. In total, 71% were women, and 91% were White, with all chronic kidney disease (CKD) stages represented. In total, 2.5% reported being treated with dialysis, and 23% had a kidney transplant. CKD stage 4/5 participants reported the most dull kidney pain, whereas sharp kidney pain was evenly distributed across early CKD stages. Dull kidney pain had an impact on sleep regardless of CKD stage. There was a strong positive correlation between the ADPKD-PDS and ADPKD-IS. Patients with a neutral or positive HRQoL were less likely to have been denied access to imaging or other care.
UNASSIGNED: Currently, all the information collected is patient reported without health record validation of clinical variables.
UNASSIGNED: Use of the HRQoL tools in the ADPKD Registry provided a broad cross-sectional assessment in the United States and provided granular information on the burden of pain across the CKD spectrum in ADPKD. The ADPKD Registry allowed assessment of ADPKD impact in a community that experiences decline in health and kidney function over decades.
The Autosomal Dominant Polycystic Kidney Disease Registry is a longitudinal, patient-powered research tool created with the goal to better understand the impacts of ADPKD on affected individuals in the United States. Here, we analyze pain and other health-related quality of life outcomes in 1,086 individuals using validated tools and comment on the utility of these tools for future use in clinical trials and observational studies. We found that sharp pain, dull pain, fullness discomfort, and other related impacts affected individuals across the disease spectrum, although some participants reported more dull pain in later stages (CKD stages 4 and 5). Future analysis of these trends over time will be valuable in understanding how to assess and address the burden of pain in autosomal dominant polycystic kidney disease.

UNASSIGNED: Alport Syndrome (AS) is a progressive genetic condition characterized by chronic kidney disease (CKD), hearing loss, and eye abnormalities. It is caused by mutations in the genes COL4A3, COL4A4, and COL4A5. Heterozygous mutations in COL4A4 and COL4A3 cause autosomal dominant Alport Syndrome (ADAS), and a spectrum of phenotypes ranging from asymptomatic hematuria to CKD, with variable extra-renal features. In the past, heterozygous mutations in these genes were thought to be benign, however recent studies show that about 30% of patients can progress to CKD, and 15% can progress to end stage kidney disease (ESKD).
UNASSIGNED: We present a case of a woman who was noted to have microscopic hematuria pre-living kidney donation. Genetic testing revealed a heterozygous variant of uncertain significance (VUS) in the COL4A4 gene. VUSs are medically nonactionable findings and data show that VUSs can be detected in 41% of all patients who undergo clinical genetic testing. VUSs frustrate clinicians and patients alike. Although they cannot be used in medical decision-making, data suggest that reanalysis can result in the reclassification of a VUS over time.
UNASSIGNED: Post-donation, the index patient had a higher than anticipated rise in serum creatinine, raising a concern for possible intrinsic kidney disease. Kidney biopsy was deemed high risk in the setting of a unilateral kidney thereby limiting possible diagnostic intervention to determine the cause of disease.
UNASSIGNED: Re-evaluation of prior genetic testing results and reassessment of the previously identified VUS in COL4A4 was performed 5-years post-donation. These analyses, along with the addition of new phenotypic data and extended pedigree data, resulted in the reclassification of the previously identified VUS to a likely pathogenic variant.
UNASSIGNED: This case demonstrates the importance of structured, periodic re-evaluation of genetic testing results. With the ever-changing landscape of genetics in medicine, the interpretation of a VUS can be dynamic and therefore warrant caution in living kidney donor evaluations. Studies have shown that about 10% of VUSs can be upgraded to a pathogenic classification after an 18- to 36-month interval. Structured re-evaluation of genomic testing results has not yet been integrated into clinical practice and poses a unique challenge in living kidney donation.
UNASSIGNED: This case report highlights the variability of the ADAS phenotype caused by pathogenic heterozygous variants in the type 4 collagen genes. It supports the nomenclature change from a benign hematuria phenotype to ADAS, particularly when additional risk factors such as proteinuria, focal segmental glomerulosclerosis or glomerular basement membrane changes on kidney biopsy are present, or as in this case, evidence of disease in other family members.
UNASSIGNED: Le syndrome d’Alport (SA) est une maladie génétique progressive caractérisée par une insuffisance rénale chronique (IRC), une perte auditive et des anomalies oculaires. La maladie est causée par des mutations dans les gènes COL4A3, COL4A4 et COL4A5. Des mutations hétérozygotes dans les gènes COL4A4 et COL4A3 provoquent le syndrome d’Alport autosomique dominant (SAAD) et un specter de phénotypes allant de l’hématurie asymptomatique à l’IRC, avec des caractéristiques extrarénales variables. Dans le passé, les mutations hétérozygotes de ces gènes étaient considérées comme bénignes, mais des études récentes montrent qu’environ 30 % des patients peuvent progresser vers l’IRC et 15 % vers l’insuffisance rénale terminale (IRT).
UNASSIGNED: Nous présentons le cas d’une femme chez qui on avait observé une hématurie microscopique avant un don vivant de rein. Les tests génétiques ont révélé un variant hétérozygote de signification incertaine dans le gène COL4A4. Les variants de signification incertaine (VSI) sont des résultats qui ne peuvent être utilisés médicalement et les données montrent qu’ils peuvent être détectés chez 41 % des patients qui subissent des tests génétiques cliniques. Les VSI sont frustrants tant pour les cliniciens que pour les patients. Bien qu’ils ne puissent pas être utilisés dans la prise de décisions médicales, les données suggèrent que leur réanalyse pourrait entraîner leur reclassification au fil du temps.
UNASSIGNED: Après le don, ce cas index a présenté une élévation de la créatinine sérique plus importante que prévu, ce qui a soulevé une préoccupation quant à la présence d’une néphropathie intrinsèque. La biopsie rénale a été jugée à haut risque dans le contexte de rein unilatéral, ce qui a limité la possible intervention diagnostique pour déterminer la cause de la maladie.
UNASSIGNED: La réévaluation des résultats des tests génétiques antérieurs et du VSI précédemment identifié dans COL4A4 a été réalisée 5 ans après le don. Ces analyses, ainsi que l’ajout de nouvelles données phénotypiques et de données généalogiques étendues, ont abouti à la reclassification du VSI précédemment identifié en variant probablement pathogène.
UNASSIGNED: Ce cas illustre l’importance de réévaluer de façon structurée et périodique les résultats des tests génétiques. La génétique étant en constante évolution en médecine, l’interprétation d’un VSI peut être dynamique et, ainsi, justifier la prudence dans les évaluations des donneurs de reins vivants. Des études ont montré qu’environ 10 % des VSI peuvent être reclassés comme pathogènes après 18 à 36 mois. La réévaluation structurée des résultats des tests génomiques, qui n’a pas encore été intégrée dans la pratique clinique, pose un défi unique dans le contexte d’un don vivant de reins.
UNASSIGNED: Ce rapport de cas met en évidence la variabilité du phénotype du SAAD causé par des variants hétérozygotes pathogènes dans les gènes du collagène de type 4. Il soutient un changement de nomenclature du phénotype d’hématurie bénigne en SAAD, en particulier en présence de facteurs de risque supplémentaires tels que la protéinurie et la glomérulosclérose segmentaire et focale, de modifications de la membrane basale glomérulaire sur la biopsie rénale ou, comme dans ce cas, de preuves de la maladie chez d’autres membres de la famille.

Nephrolithiasis (NL) is a common condition worldwide. The incidence of NL and nephrocalcinosis (NC) has been increasing, along with their associated morbidity and economic burden. The etiology of NL and NC is multifactorial and includes both environmental components and genetic components, with multiple studies showing high heritability. Causative gene variants have been detected in up to 32% of children with NL and NC. Children with NL and NC are genotypically heterogenous, but often phenotypically relatively homogenous, and there are subsequently little data on the predictors of genetic childhood NL and NC. Most genetic diseases associated with NL and NC are secondary to hypercalciuria, including those secondary to hypercalcemia, renal phosphate wasting, renal magnesium wasting, distal renal tubular acidosis (RTA), proximal tubulopathies, mixed or variable tubulopathies, Bartter syndrome, hyperaldosteronism and pseudohyperaldosteronism, and hyperparathyroidism and hypoparathyroidism. The remaining minority of genetic diseases associated with NL and NC are secondary to hyperoxaluria, cystinuria, hyperuricosuria, xanthinuria, other metabolic disorders, and multifactorial etiologies. Genome-wide association studies (GWAS) in adults have identified multiple polygenic traits associated with NL and NC, often involving genes that are involved in calcium, phosphorus, magnesium, and vitamin D homeostasis. Compared to adults, there is a relative paucity of studies in children with NL and NC. This review aims to focus on the genetic component of NL and NC in children.

BACKGROUND: Chronic kidney disease affects 10% of the world population, and it is associated with progression to end-stage kidney disease and increased morbidity and mortality. The advent of multi-omics technologies has expanded our knowledge on the complexity of kidney diseases, revealing their frequent genetic etiology, particularly in children and young subjects. Genetic heterogeneity and drug screening require patient-derived disease models to establish a correct diagnosis and evaluate new potential treatments and outcomes.
CONCLUSIONS: Patient-derived renal progenitors can be isolated from urine to set up proper disease modeling. This strategy allows to make diagnosis of genetic kidney disease in patients carrying unknown significance variants or uncover variants missed from peripheral blood analysis. Furthermore, urinary-derived tubuloids obtained from renal progenitors of patients appear to be potentially valuable for modeling kidney diseases to test ex vivo treatment efficacy or to develop new therapeutic approaches. Finally, renal progenitors derived from urine can provide insights into acute kidney injury and predict kidney function recovery and outcome.
CONCLUSIONS: Renal progenitors derived from urine are a promising new noninvasive and easy-to-handle tool, which improves the rate of diagnosis and the therapeutic choice, paving the way toward a personalized healthcare.

OBJECTIVE: Alport syndrome (AS) is the most common genetic glomerular disease caused by mutations that affect type IV collagen. However, the clinical characteristics and significance of AS with kidney cysts are not well defined. This study investigated the prevalence and clinical significance of cystic kidney phenotype in AS.
METHODS: Retrospective cohort study.
METHODS: One hundred-eight patients with AS and a comparison cohort of 79 patients with IgA nephropathy (IgAN). Clinical, genetic, and imaging data were collected from medical records.
METHODS: Cystic kidney phenotype evaluated by ultrasonography and defined as the presence of≥3 cysts in each kidney; demographic characteristics and estimated glomerular filtration rate (eGFR) at disease onset.
RESULTS: Cystic kidney phenotype in the AS and IgAN cohorts; time to chronic kidney disease (CKD) stage 3b and longitudinal changes in eGFR in the AS cohort.
METHODS: Logistic regression analysis to test independent strengths of associations of clinical/demographic features with the binary outcome of cystic phenotype. Survival analysis for the outcome of reaching CKD stage 3b and linear mixed models for changes in eGFR over time in the AS cohort.
RESULTS: We studied 108 patients with AS; 76 (70%) had a genetic diagnosis. Autosomal dominant AS was prevalent, accounting for 68% of patients with a genetic diagnosis. Cystic kidney phenotype was observed in 38% of patients with AS and was associated with normal-sized kidneys in all but 3 patients, who showed increased total kidney volume, mimicking autosomal dominant polycystic kidney disease. The prevalence of cystic kidney phenotype was significantly higher in patients with AS when compared with the group of patients with IgAN (42% vs 19%; P=0.002). Patients with the cystic kidney phenotype were older and had more marked reduction in eGFR than patients without cystic changes. Among patients with AS, the cystic phenotype was associated with older age and a faster decline eGFR.
CONCLUSIONS: Retrospective, single-center study.
CONCLUSIONS: Cystic kidney phenotype is a common finding in AS. The cystic kidney phenotype is a common finding in AS, suggesting a possible role in cystogenesis for the genetic variants that cause this disease.
UNASSIGNED: Hematuria is the classic renal presentation of Alport syndrome (AS), a hereditary glomerulopathy caused by pathogenic variants of the COL4A3-5 genes. An atypical kidney cystic phenotype has been rarely reported in individuals with these variants. To determine the prevalence of kidney cysts, we performed abdominal ultrasonography in a large group of patients with AS and a comparison group of patients with another glomerular kidney disease, IgA nephropathy (IgAN). Multiple kidney cysts, usually with normal kidney volume, were found in 38% of patients with AS. A few patients\' kidney volumes were large enough to mimic a different hereditary cystic kidney disease, autosomal dominant polycystic kidney disease. The overall prevalence of kidney cysts in AS was more than double that observed in the well-matched comparison group with IgAN. These findings emphasize the high prevalence of cystic kidney phenotype in AS, suggesting a likely association between the genetic variants that cause this disease and the development of kidney cysts.

Despite increasing awareness of genetic kidney disease prevalence, there is limited population-level information about long term outcomes of people with genetic kidney disease receiving kidney replacement therapy. This analysis included people who commenced kidney replacement therapy between 1989 and 2020 as recorded in the Australian and New Zealand Dialysis and Transplant registry. Genetic kidney diseases were subclassified as majority and minority monogenic. Non-genetic kidney diseases were included as the comparator group. Primary outcome measures were 10-year mortality and 10-year graft failure. Cox proportional hazard regression were used to calculate unadjusted and adjusted hazard ratios (AHRs) for primary outcomes. There were 59,231 people in the dialysis subgroup and 21,860 people in the transplant subgroup. People on dialysis with genetic kidney diseases had reduced 10-year mortality risk (majority monogenic AHR: 0.70, 95% CI 0.66-0.76; minority monogenic AHR 0.86, 95% CI 0.80-0.92). This reduced 10-year mortality risk continued after kidney transplantation (majority monogenic AHR: 0.82, 95% CI 0.71-0.93; minority monogenic AHR 0.80, 95% CI 0.68-0.95). Majority monogenic genetic kidney diseases were associated with reduced 10-year graft failure compared to minority monogenic genetic kidney diseases and other kidney diseases (majority monogenic AHR 0.69, 95% CI 0.59-0.79). This binational registry analysis identified that people with genetic kidney disease have different mortality and graft failure risks compared to people with other kidney diseases.