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While up to 50% of children requiring kidney replacement therapy have congenital anomalies of the kidney and urinary tract (CAKUT), they represent only a fraction of the total patient population with CAKUT. The extreme variability in clinical outcome underlines the fundamental need to devise personalized clinical management strategies for individuals with CAKUT. Better understanding of the pathophysiology of abnormal kidney and urinary tract development provides a framework for precise diagnoses and prognostication of patients, the identification of biomarkers and disease modifiers, and, thus, the development of personalized strategies for treatment. In this review, we provide a state-of-the-art overview of the currently known genetic causes, including rare variants in kidney and urinary tract development genes, genomic disorders, and common variants that have been attributed to CAKUT. Furthermore, we discuss the impact of environmental factors and their interactions with developmental genes in kidney and urinary tract malformations. Finally, we present multi-angle translational modalities to validate candidate genes and environmental factors and shed light on future strategies to better understand the molecular underpinnings of CAKUT. [ABSTRACT FROM AUTHOR]

Variants in the CNNM2 gene are causative for hypomagnesaemia, seizures and intellectual disability, although the phenotypes can be variable. This study aims to understand the genotype–phenotype relationship in affected individuals with CNNM2 variants by phenotypic, functional and structural analysis of new as well as previously reported variants. This results in the identification of seven variants that significantly affect CNNM2-mediated Mg2+ transport. Pathogenicity of these variants is further supported by structural modelling, which predicts CNNM2 structure to be affected by all of them. Strikingly, seizures and intellectual disability are absent in 4 out of 7 cases, indicating these phenotypes are caused either by specific CNNM2 variant only or by additional risk factors. Moreover, in line with sporadic observations from previous reports, CNNM2 variants might be associated with disturbances in parathyroid hormone and Ca2+ homeostasis. [ABSTRACT FROM AUTHOR]

Glomerular nephropathy resulting from the genetic defects in COL4A3/4/5 genes including the classical Alport syndrome (AS) is the second commonest hereditary kidney disease characterized by persistent haematuria progressing to the need of kidney replacement therapy, frequently associated with sensorineural deafness, and occasionally with ocular anomalies. Diagnosis and management of COL4A3/4/5 glomerulopathy is a great challenge due to its phenotypic heterogeneity, multiple modes of inheritance, variable expressivity, and disease penetrance of individual variants as well as imperfect prognostic and progression factors and scarce and limited clinical trials, especially in children. As a joint initiative of the European Rare Kidney disease reference Network (ERKNet), European Renal Association (ERA Genes&Kidney) and European Society for Paediatric Nephrology (ESPN) Working Group Hereditary Kidney Disorders, a team of experts including adult and paediatric nephrologists, kidney geneticists, audiologists, ophthalmologists and a kidney pathologist were selected to perform a systematic literature review on 21 clinically relevant PICO (Patient or Population covered, Intervention, Comparator, Outcome) questions. The experts formulated recommendations and formally graded them at a consensus meeting with input from patient representatives and a voting panel of nephrologists representing all regions of the world. Genetic diagnostics comprising joint analysis of COL4A3/4/5 genes is the key diagnostic test already during the initial evaluation of an individual presenting with persistent haematuria, proteinuria, kidney failure of unknown origin, focal segmental sclerosis of unknown origin and possibly cystic kidney disease. Early renin-angiotensin system blockade is the standard of care therapy; sodium-glucose cotransporter-2 inhibitors may be added in adults with proteinuria and chronic kidney disease. Relatives with heterozygous COL4A3/4/5 variants should only be considered as the last possible resource for living kidney donation. This guideline provides guidance for the diagnosis and management of individuals with pathogenic variants in COL4A3/4/5 genes., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

Background and Hypothesis: Chronic kidney disease (CKD) remains unexplained in at least 20% of patients. Massively parallel sequencing (MPS) can be a valuable diagnostic tool in patients with unexplained CKD, but prospective data from routine clinical practice are limited. We aimed to determine the diagnostic yield and relevance of MPS-based gene panel testing in patients with unexplained CKD in a real-world context. We additionally examined barriers to implementation of genetic testing., Methods: In this prospective cohort study, we recruited patients with unexplained CKD (eGFR <60mL/min/1.73 m2 without underlying clinical diagnosis) with onset <50 years who underwent MPS-based multi-gene panel testing from 11 academic and non-academic hospitals across the Netherlands. In patients with a (likely) pathogenic variant, we verified that the variant likely explained the clinical phenotype. A nationwide online survey was sent out to all Dutch nephrologists and residents to investigate potential barriers for gene panel testing., Results: A diagnostic variant was identified in 59/340 participants (17%). Most common diagnostic variants were in NPHP1 (13 patients), COL4A3 (12 patients), COL4A4 (5 patients), COL4A5 (6 patients), and PAX2 (5 patients). A genetic diagnosis led to at least one clinical consequence in 73% of patients. Main barriers reported by Dutch nephrologists (N=71) included genetic illiteracy (53%), difficulties with test selection (51%), and lack of time (43%)., Conclusion: MPS-based multi-gene panel testing yielded a genetic diagnosis in 17% of patients with unexplained CKD. Our findings support the relevance of MPS in the diagnostic workup of adults with unexplained CKD with onset <50 years. Additionally, our results underline the need to improve genetic education among nephrologists to better the implementation of MPS-based diagnostic testing in clinical practice., (© The Author(s) 2024. Published by Oxford University Press on behalf of the ERA.)

Four European Reference Networks (ERN-EYE, ERKNet, Endo-ERN, ERN-ITHACA) have teamed up to establish a consensus statement and recommendations for Bardet-Biedl syndrome (BBS). BBS is an autosomal recessive ciliopathy with at least 26 genes identified to date. The clinical manifestations are pleiotropic, can be observed in utero and will progress with age. Genetic testing has progressively improved in the last years prompting for a revision of the diagnostic criteria taking into account clinical Primary and Secondary features, as well as positive or negative molecular diagnosis. This consensus statement also emphasizes on initial diagnosis, monitoring and lifelong follow-up, and symptomatic care that can be provided to patients and family members according to the involved care professionals. For paediatricians, developmental anomalies can be at the forefront for diagnosis (such as polydactyly) but can require specific care, such as for associated neuro developmental disorders. For ophthalmology, the early onset retinal degeneration requires ad hoc functional and imaging technologies and specific care for severe visual impairment. For endocrinology, among other manifestations, early onset obesity and its complications has benefited from better evaluation of eating behaviour problems, improved lifestyle programs, and from novel pharmacological therapies. Kidney and urinary track involvements warrants lifespan attention, as chronic kidney failure can occur and early management might improve outcome. This consensus recommends revised diagnostic criteria for BBS that will ensure certainty of diagnosis, giving robust grounds for genetic counselling as well as in the perspective of future trials for innovative therapies., Competing Interests: Competing interests The development of this work was made without external financial support from industries involved in the manufacturing of therapies for BBS. Competing interests of members of the guideline development group have been recorded in writing and addressed. HD has consulted for Novartis, Rhythm Pharmaceuticals, Jansen Pharmaceutical, GenSight Biologics and Sparing Vision. JK, DL, AG, MMVH and JM have consulted for Rhythm Pharmaceuticals. EVDA’s institute was the recipient of a research grant from Rhythm Pharmaceuticals. MC is a principal investigator for the RM-IMC-901 study (a Registry of Patients with Biallelic Proopiomelanocortin (POMC), Proprotein Convertase Subtilisin/Kexin Type 1 (PCSK1), or Leptin Receptor (LEPR) Deficiency Obesity, or Bardet-Biedl Syndrome (BBS), Treated with Setmelanotide) and received payments for lectures, expert testimony and consulting fees and study support from Rhythm Pharmaceuticals; MC also received payments for lectures from Canon Medical Systems. CB is the medical and managing director of Medizinische Genetik Mainz and Limbach Genetics. BPL has consulted for Novartis, Jansen Pharmaceutical, GenSight Biologics and Sparing Vision. CP has consulted for Rhythm Pharmaceuticals and Novo Nordisk. SR has consulted for Rhythm Pharmaceuticals, Sandoz and Novo Nordisk. MRL, PM, AV, GMB, MGP, FT, MFS, FS, AG, MZ, HM, AMVE, DM, AS, DV, have no competing interests to declare., (© 2024. The Author(s).)

Introduction: Family planning and reproductive care are essential but complex aspects of lifecycle management for individuals with autosomal dominant polycystic kidney disease (ADPKD), given the potential genetic transmission and pregnancy-related complications. In this qualitative study, we studied the experiences and perspectives of patients with ADPKD and clinicians to identify areas for potential improvement in reproductive lifecycle care., Methods: Focus group discussions (FGDs) were conducted in the Netherlands with patients with ADPKD, both men and women, who had children through varied reproductive choices; and clinicians, including (pediatric) nephrologists, obstetric gynecologists and geneticists. Thematic analysis, utilizing a grounded theory approach, was performed on verbatim transcriptions of recordings, followed by consensus discussions to finalize themes., Results: Nine focus groups involving 31 participants (16 patients and 15 physicians) identified 6 key themes. These included the need for timely and comprehensive information dissemination from puberty on, understanding patient-specific decision-making factors, improving tailored psychosocial guidance and communication, the need for systematic efforts to take care of missed (minor) at-risk patients, addressing inequities in access to care, and improving multidisciplinary collaboration., Conclusions: This study represents the first qualitative study of patient and physician perspectives on reproductive lifecycle care for ADPKD. We present valuable insights into factors influencing patients' reproductive decision-making, a comprehensive comparison between the perspectives of patients and clinicians on family planning and follow-up care of minors at risk for ADPKD, and recommendations for enhancing overall care quality. Incorporating these insights into clinical care could enhance patient-centered care and foster interdisciplinary collaborations to further improve the quality of reproductive health care services for individuals with ADPKD., (© 2024 International Society of Nephrology. Published by Elsevier Inc.)

Introduction: Genetic testing can reveal monogenic causes of kidney diseases, offering diagnostic, therapeutic, and prognostic benefits. Although single nucleotide variants (SNVs) and copy number variants (CNVs) can result in kidney disease, CNV analysis is not always included in genetic testing., Methods: We investigated the diagnostic value of CNV analysis in 2432 patients with kidney disease genetically tested at the University Medical Centre Utrecht between 2014 and May 2022. We combined previous diagnostic testing results, encompassing SNVs and CNVs, with newly acquired results based on retrospective CNV analysis. The reported yield considers both the American College of Medical Genetics and Genomics (ACMG) classification and whether the genotype actually results in disease., Results: We report a diagnostic yield of at least 23% for our complete diagnostic cohort. The total diagnostic yield based solely on CNVs was 2.4%. The overall contribution of CNV analysis, defined as the proportion of positive genetic tests requiring CNV analysis, was 10.5% and varied among different disease subcategories, with the highest impact seen in congenital anomalies of the kidney and urinary tract (CAKUT) and chronic kidney disease at a young age. We highlight the efficiency of exome-based CNV calling, which reduces the need for additional diagnostic tests. Furthermore, a complex structural variant, likely a COL4A4 founder variant, was identified. Additional findings unrelated to kidney diseases were reported in a small percentage of cases., Conclusion: In summary, this study demonstrates the substantial diagnostic value of CNV analysis, providing insights into its contribution to the diagnostic yield and advocating for its routine inclusion in genetic testing of patients with kidney disease., (© 2024 International Society of Nephrology. Published by Elsevier Inc.)

Introduction: Hepatocyte nuclear factor 1-beta ( HNF1B ) gene variants or the chromosome 17q12 deletion (17q12del) represent the most common monogenic cause of developmental kidney disease. Although neurodevelopmental disorders have been associated with the 17q12del, specific genotype-phenotype associations with respect to kidney function evolution have not yet been fully defined. Here, we aimed to determine whether 17q12del or specific HNF1B variants were associated with kidney survival in a large patient population with HNF1B disease., Methods: This was a retrospective observational study involving 521 patients with HNF1B disease from 14 countries using the European Reference Network for rare kidney diseases with detailed information on the HNF1B genotype ( HNF1B variants or the 17q12del). Median follow-up time was 11 years with 6 visits per patient. The primary end point was progression to chronic kidney disease (CKD) stage 3 (estimated glomerular filtration rate [eGFR] < 60 ml/min per 1.73 m 2 ). Secondary end points were the development of hypomagnesemia or extrarenal disorders, including hyperuricemia and hyperglycemia., Results: Progression toward CKD stage 3 was significantly delayed in patients with the 17q12del compared to patients with HNF1B variants (hazard ratio [HR]: 0.29, 95% confidence interval [CI]: 0.19-0.44, P  < 0.001). Progression toward CKD stage 3 was also significantly delayed when HNF1B variants involved the HNF1B Pit-1, Oct-1, and Unc-86 homeodomain (POU h ) DNA-binding and transactivation domains rather than the POU-specific domain (POU s ) DNA-binding domain (HR: 0.15 [95% CI: 0.06-0.37), P  < 0.001 and HR: 0.25 (95% CI: 0.11-0.57), P  = 0.001, respectively). Finally, the 17q12del was positively associated with hypomagnesemia and negatively associated with hyperuricemia, but not with hyperglycemia., Conclusion: Patients with the 17q12del display a significantly better kidney survival than patients with other HNF1B variants; and for the latter, variants in the POU s DNA-binding domain lead to the poorest kidney survival. These are clinically relevant HNF1B kidney genotype-phenotype correlations that inform genetic counseling., (© 2024 International Society of Nephrology. Published by Elsevier Inc.)

Individualized pre-pregnancy counseling and antenatal care for women with chronic kidney disease (CKD) require disease-specific data. Here, we investigated pregnancy outcomes and long-term kidney function in women with COL4A3-5 related disease (Alport Syndrome, (AS)) in a large multicenter cohort. The ALPART-network (mAternaL and fetal PregnAncy outcomes of women with AlpoRT syndrome), an international collaboration of 17 centers, retrospectively investigated COL4A3-5 related disease pregnancies after the 20th week. Outcomes were stratified per inheritance pattern (X-Linked AS (XLAS)), Autosomal Dominant AS (ADAS), or Autosomal Recessive AS (ARAS)). The influence of pregnancy on estimated glomerular filtration rate (eGFR)-slope was assessed in 192 pregnancies encompassing 116 women (121 with XLAS, 47 with ADAS, and 12 with ARAS). Median eGFR pre-pregnancy was over 90ml/min/1.73m 2 . Neonatal outcomes were favorable: 100% live births, median gestational age 39.0 weeks and mean birth weight 3135 grams. Gestational hypertension occurred during 23% of pregnancies (reference: 'general' CKD G1-G2 pregnancies incidence is 4-20%) and preeclampsia in 20%. The mean eGFR declined after pregnancy but remained within normal range (over 90ml/min/1.73m 2 ). Pregnancy did not significantly affect eGFR-slope (pre-pregnancy β=-1.030, post-pregnancy β=-1.349). ARAS-pregnancies demonstrated less favorable outcomes (early preterm birth incidence 3/11 (27%)). ARAS was a significant independent predictor for lower birth weight and shorter duration of pregnancy, next to the classic predictors (pre-pregnancy kidney function, proteinuria, and chronic hypertension) though missing proteinuria values and the small ARAS-sample hindered analysis. This is the largest study to date on AS and pregnancy with reassuring results for mild AS, though inheritance patterns could be considered in counseling next to classic risk factors. Thus, our findings support personalized reproductive care and highlight the importance of investigating kidney disease-specific pregnancy outcomes., (Copyright © 2024 International Society of Nephrology. All rights reserved.)

Medullary sponge kidney (MSK) is a description of radiographic features. However, the pathogenesis of MSK remains unclear. MSK is supposed to be the cause of secondary distal renal tubular acidosis (dRTA), although there are case reports suggesting that MSK is a complication of primary dRTA. In addition to these reports, we report 3 patients with metabolic acidosis and MSK, in whom primary dRTA is confirmed by molecular genetic analyses of SLC4A1 and ATP6V1B1 genes. With a comprehensive genetics-first approach using the 100,000 Genomes Rare Diseases Project dataset, the association between MSK and primary dRTA is examined. We showed that many patients with MSK phenotypes are genetically tested with a gene panel which does not contain dRTA-associated genes, revealing opportunities for missed genetic diagnosis. Our cases highlight that the radiological description of MSK is not a straightforward disease or clinical phenotype. Therefore, when an MSK appearance is noted, a broader set of causes should be considered including genetic causes of primary dRTA as the underlying reason for medullary imaging abnormalities., (© 2024 The Author(s). Published by S. Karger AG, Basel.)

To discover rare disease-gene associations, we developed a gene burden analytical framework and applied it to rare, protein-coding variants from whole genome sequencing of 35,008 cases with rare diseases and their family members recruited to the 100,000 Genomes Project (100KGP). Following in silico triaging of the results, 88 novel associations were identified including 38 with existing experimental evidence. We have published the confirmation of one of these associations, hereditary ataxia with UCHL1 , and independent confirmatory evidence has recently been published for four more. We highlight a further seven compelling associations: hypertrophic cardiomyopathy with DYSF and SLC4A3 where both genes show high/specific heart expression and existing associations to skeletal dystrophies or short QT syndrome respectively; monogenic diabetes with UNC13A with a known role in the regulation of β cells and a mouse model with impaired glucose tolerance; epilepsy with KCNQ1 where a mouse model shows seizures and the existing long QT syndrome association may be linked; early onset Parkinson's disease with RYR1 with existing links to tremor pathophysiology and a mouse model with neurological phenotypes; anterior segment ocular abnormalities associated with POMK showing expression in corneal cells and with a zebrafish model with developmental ocular abnormalities; and cystic kidney disease with COL4A3 showing high renal expression and prior evidence for a digenic or modifying role in renal disease. Confirmation of all 88 associations would lead to potential diagnoses in 456 molecularly undiagnosed cases within the 100KGP, as well as other rare disease patients worldwide, highlighting the clinical impact of a large-scale statistical approach to rare disease gene discovery.

Genetic testing in patients with suspected hereditary kidney disease may not reveal the genetic cause for the disorder as potentially pathogenic variants can reside in genes that are not yet known to be involved in kidney disease. We have developed KidneyNetwork, that utilizes tissue-specific expression to inform candidate gene prioritization specifically for kidney diseases. KidneyNetwork is a novel method constructed by integrating a kidney RNA-sequencing co-expression network of 878 samples with a multi-tissue network of 31,499 samples. It uses expression patterns and established gene-phenotype associations to predict which genes could be related to what (disease) phenotypes in an unbiased manner. We applied KidneyNetwork to rare variants in exome sequencing data from 13 kidney disease patients without a genetic diagnosis to prioritize candidate genes. KidneyNetwork can accurately predict kidney-specific gene functions and (kidney disease) phenotypes for disease-associated genes. The intersection of prioritized genes with genes carrying rare variants in a patient with kidney and liver cysts identified ALG6 as plausible candidate gene. We strengthen this plausibility by identifying ALG6 variants in several cystic kidney and liver disease cases without alternative genetic explanation. We present KidneyNetwork, a publicly available kidney-specific co-expression network with optimized gene-phenotype predictions for kidney disease phenotypes. We designed an easy-to-use online interface that allows clinicians and researchers to use gene expression and co-regulation data and gene-phenotype connections to accelerate advances in hereditary kidney disease diagnosis and research. TRANSLATIONAL STATEMENT: Genetic testing in patients with suspected hereditary kidney disease may not reveal the genetic cause for the patient's disorder. Potentially pathogenic variants can reside in genes not yet known to be involved in kidney disease, making it difficult to interpret the relevance of these variants. This reveals a clear need for methods to predict the phenotypic consequences of genetic variation in an unbiased manner. Here we describe KidneyNetwork, a tool that utilizes tissue-specific expression to predict kidney-specific gene functions. Applying KidneyNetwork to a group of undiagnosed cases identified ALG6 as a candidate gene in cystic kidney and liver disease. In summary, KidneyNetwork can aid the interpretation of genetic variants and can therefore be of value in translational nephrogenetics and help improve the diagnostic yield in kidney disease patients., (© 2023. The Author(s).)

Approval of the vasopressin V2 receptor antagonist tolvaptan-based on the landmark TEMPO 3:4 trial-marked a transformation in the management of autosomal dominant polycystic kidney disease (ADPKD). This development has advanced patient care in ADPKD from general measures to prevent progression of chronic kidney disease to targeting disease-specific mechanisms. However, considering the long-term nature of this treatment, as well as potential side effects, evidence-based approaches to initiate treatment only in patients with rapidly progressing disease are crucial. In 2016, the position statement issued by the European Renal Association (ERA) was the first society-based recommendation on the use of tolvaptan and has served as a widely used decision-making tool for nephrologists. Since then, considerable practical experience regarding the use of tolvaptan in ADPKD has accumulated. More importantly, additional data from REPRISE, a second randomized clinical trial (RCT) examining the use of tolvaptan in later-stage disease, have added important evidence to the field, as have post hoc studies of these RCTs. To incorporate this new knowledge, we provide an updated algorithm to guide patient selection for treatment with tolvaptan and add practical advice for its use., (© The Author(s) 2021. Published by Oxford University Press on behalf of the ERA.)

Background: Often only chronic kidney disease (CKD) patients with high likelihood of genetic disease are offered genetic testing. Early genetic testing could obviate the need for kidney biopsies, allowing for adequate prognostication and treatment. To test the viability of a 'genetics-first' approach for CKD, we performed genetic testing in a group of kidney transplant recipients aged <50 years, irrespective of cause of transplant., Methods: From a cohort of 273 transplant patients, we selected 110 that were in care in the University Medical Center Utrecht, had DNA available and were without clear-cut non-genetic disease. Forty patients had been diagnosed with a genetic disease prior to enrollment; in 70 patients, we performed a whole-exome sequencing-based 379 gene panel analysis., Results: Genetic analysis yielded a diagnosis in 51%. Extrapolated to the 273 patient cohort, who did not all fit the inclusion criteria, the diagnostic yield was still 21%. Retrospectively, in 43% of biopsied patients, the kidney biopsy would not have had added diagnostic value if genetic testing had been performed as a first-tier diagnostic., Conclusions: The burden of monogenic disease in transplant patients with end-stage kidney disease (ESKD) of any cause prior to the age of 50 years is between 21% and 51%. Early genetic testing can provide a non-invasive diagnostic, impacting prognostication and treatment, and obviating the need for an invasive biopsy. We conclude that in patients who expect to develop ESKD prior to the age of 50 years, genetic testing should be considered as first mode of diagnostics., (© The Author(s) 2020. Published by Oxford University Press on behalf of the ERA.)

The recent Chandos House meeting of the Alport Variant Collaborative extended the indications for screening for pathogenic variants in the COL4A5, COL4A3 and COL4A4 genes beyond the classical Alport phenotype (haematuria, renal failure; family history of haematuria or renal failure) to include persistent proteinuria, steroid-resistant nephrotic syndrome, focal and segmental glomerulosclerosis (FSGS), familial IgA glomerulonephritis and end-stage kidney failure without an obvious cause. The meeting refined the ACMG criteria for variant assessment for the Alport genes (COL4A3-5). It identified 'mutational hotspots' (PM1) in the collagen IV α5, α3 and α4 chains including position 1 Glycine residues in the Gly-X-Y repeats in the intermediate collagenous domains; and Cysteine residues in the carboxy non-collagenous domain (PP3). It considered that 'well-established' functional assays (PS3, BS3) were still mainly research tools but sequencing and minigene assays were commonly used to confirm splicing variants. It was not possible to define the Minor Allele Frequency (MAF) threshold above which variants were considered Benign (BA1, BS1), because of the different modes of inheritances of Alport syndrome, and the occurrence of hypomorphic variants (often Glycine adjacent to a non-collagenous interruption) and local founder effects. Heterozygous COL4A3 and COL4A4 variants were common 'incidental' findings also present in normal reference databases. The recognition and interpretation of hypomorphic variants in the COL4A3-COL4A5 genes remains a challenge., (© 2021. The Author(s).)

Monoallelic mutations of DNAJB11 were recently described in seven pedigrees with atypical clinical presentations of autosomal dominant polycystic kidney disease. DNAJB11 encodes one of the main cofactors of the endoplasmic reticulum chaperon BiP, a heat-shock protein required for efficient protein folding and trafficking. Here we conducted an international collaborative study to better characterize the DNAJB11-associated phenotype. Thirteen different loss-of-function variants were identified in 20 new pedigrees (54 affected individuals) by targeted next-generation sequencing, whole-exome sequencing or whole-genome sequencing. Amongst the 77 patients (27 pedigrees) now in total reported, 32 reached end stage kidney disease (range, 55-89 years, median age 75); without a significant difference between males and females. While a majority of patients presented with non-enlarged polycystic kidneys, renal cysts were inconsistently identified in patients under age 45. Vascular phenotypes, including intracranial aneurysms, dilatation of the thoracic aorta and dissection of a carotid artery were present in four pedigrees. We accessed Genomics England 100,000 genomes project data, and identified pathogenic variants of DNAJB11 in nine of 3934 probands with various kidney and urinary tract disorders. The clinical diagnosis was cystic kidney disease for eight probands and nephrocalcinosis for one proband. No additional pathogenic variants likely explaining the kidney disease were identified. Using the publicly available GnomAD database, DNAJB11 genetic prevalence was calculated at 0.85/10.000 individuals. Thus, establishing a precise diagnosis in atypical cystic or interstitial kidney disease is crucial, with important implications in terms of follow-up, genetic counseling, prognostic evaluation, therapeutic management, and for selection of living kidney donors., (Copyright © 2020 International Society of Nephrology. All rights reserved.)

Progressive familial intrahepatic cholestasis (PFIC) with normal circulating gamma-glutamyl transpeptidase levels can result from mutations in the ATP8B1 gene (encoding familial intrahepatic cholestasis 1 [FIC1] deficiency) or the ABCB11 gene (bile salt export protein [BSEP] deficiency). We investigated the outcomes of partial external biliary diversion, ileal exclusion, and liver transplantation in these two conditions. We conducted a retrospective multicenter study of 42 patients with FIC1 deficiency (FIC1 patients) and 60 patients with BSEP deficiency (BSEP patients) who had undergone one or more surgical procedures (57 diversions, 6 exclusions, and 57 transplants). For surgeries performed prior to transplantation, BSEP patients were divided into two groups, BSEP-common (bearing common missense mutations D482G or E297G, with likely residual function) and BSEP-other. We evaluated clinical and biochemical outcomes in these patients. Overall, diversion improved biochemical parameters, pruritus, and growth, with substantial variation in individual response. BSEP-common or FIC1 patients survived longer after diversion without developing cirrhosis, being listed for or undergoing liver transplantation, or dying, compared to BSEP-other patients. Transplantation resolved cholestasis in all groups. However, FIC1 patients commonly developed hepatic steatosis, diarrhea, and/or pancreatic disease after transplant accompanied by biochemical abnormalities and often had continued poor growth. In BSEP patients with impaired growth, this generally improved after transplantation. Conclusion: Diversion can improve clinical and biochemical status in FIC1 and BSEP deficiencies, but outcomes differ depending on genetic etiology. For many patients, particularly BSEP-other, diversion is not a permanent solution and transplantation is required. Although transplantation resolves cholestasis in patients with FIC1 and BSEP deficiencies, the overall outcome remains unsatisfactory in many FIC1 patients; this is mainly due to extrahepatic manifestations. ( Hepatology Communications 2018;2:515-528).