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These recommendations were systematically developed on behalf of the Network for Early Onset Cystic Kidney Disease (NEOCYST) by an international group of experts in autosomal dominant polycystic kidney disease (ADPKD) from paediatric and adult nephrology, human genetics, paediatric radiology and ethics specialties together with patient representatives. They have been endorsed by the International Pediatric Nephrology Association (IPNA) and the European Society of Paediatric Nephrology (ESPN). For asymptomatic minors at risk of ADPKD, ongoing surveillance (repeated screening for treatable disease manifestations without diagnostic testing) or immediate diagnostic screening are equally valid clinical approaches. Ultrasonography is the current radiological method of choice for screening. Sonographic detection of one or more cysts in an at-risk child is highly suggestive of ADPKD, but a negative scan cannot rule out ADPKD in childhood. Genetic testing is recommended for infants with very-early-onset symptomatic disease and for children with a negative family history and progressive disease. Children with a positive family history and either confirmed or unknown disease status should be monitored for hypertension (preferably by ambulatory blood pressure monitoring) and albuminuria. Currently, vasopressin antagonists should not be offered routinely but off-label use can be considered in selected children. No consensus was reached on the use of statins, but mTOR inhibitors and somatostatin analogues are not recommended. Children with ADPKD should be strongly encouraged to achieve the low dietary salt intake that is recommended for all children.This Consensus Statement developed on behalf of the Network for Early Onset Cystic Kidney Disease provides guidance on counselling, diagnosing and monitoring children with autosomal dominant polycystic kidney disease based on current evidence and a multi-stakeholder discussion of ethical issues.

Inherited kidney diseases (IKDs) are among the leading causes of early-onset chronic kidney disease (CKD) and are responsible for at least 10–15% of cases of kidney replacement therapy (KRT) in adults. Paediatric nephrologists are very aware of the high prevalence of IKDs among their patients, but this is not the case for adult nephrologists. Recent publications have demonstrated that monogenic diseases account for a significant percentage of adult cases of CKD. A substantial number of these patients have received a non-specific/incorrect diagnosis or a diagnosis of CKD of unknown aetiology, which precludes correct treatment, follow-up and genetic counselling. There are a number of reasons why genetic kidney diseases are difficult to diagnose in adulthood: (i) adult nephrologists, in general, are not knowledgeable about IKDs; (ii) existence of atypical phenotypes; (iii) genetic testing is not universally available; (iv) family history is not always available or may be negative; (v) lack of knowledge of various genotype–phenotype relationships and (vi) conflicting interpretation of the pathogenicity of many sequence variants. Registries can contribute to visualize the burden of IKDs by regularly grouping all IKDs in their annual reports, as is done for glomerulonephritis or interstitial diseases, rather than reporting only cystic disease and hiding other IKDs under labels such as ‘miscellaneous’ or ‘other’. Any effort to reduce the percentage of patients needing KRT with a diagnosis of ‘nephropathy of unknown etiology’ or an unspecific/incorrect diagnosis should be encouraged as a step towards precision nephrology. Genetic testing may be of value in this context but should not be used indiscriminately, but rather on the basis of a deep knowledge of IKDs.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic systemic disorder causing the development of renal and hepatic cysts and decline in renal function. It affects around 1 in 1,000 live births. Early hypertension and progressive renal failure due to massive enlargement of cysts and fibrosis are hallmarks of the disease. This article reviews recent advances in ADPKD and focuses mainly on diagnosis, management, and prediction of the course of the disease.

Fabry disease is an X-linked lysosomal storage disorder that affects both sexes. Progressive cellular accumulation of glycolipids starts early in life and, if untreated, eventually leads to organ failure and premature death. The Fabry nephropathy is characterized by initial proteinuria in the second to third decades of life, and development of structural changes including glomerular sclerosis, tubular atrophy, and interstitial fibrosis. Progressive kidney failure develops at a comparable rate as in diabetic nephropathy. First signs of kidney damage may arise in childhood, prior to first signs of overt renal dysfunction underscoring the key importance of early recognition and diagnosis. Globotriaosylceramide (GL-3) deposition is probably the initiating factor of the disease pathology and, with enzyme replacement therapy (ERT), clearance can be achieved in several cell types. However, some late-stage effects are not reversible. As there is growing evidence that renal outcomes are more directly related to the degree of fibrosis and scarring, preventing the development of these irreversible changes by early initiation of ERT may have the greatest impact on renal outcomes. Proteinuria should be rigorously monitored and aggressively treated with antiproteinuric therapy. This review describes the renal clinical features and histological changes, and outline options for therapeutic intervention that offer the best hope for patients affected by this life-threatening disorder.

BackgroundFabry disease is a rare, multisystemic disorder caused by GLA gene variants that lead to alpha galactosidase A deficiency, resulting in accumulation of glycosphingolipids and cellular dysfunction. Fabry-associated clinical events (FACEs) cause significant morbidity and mortality, yet the long-term effect of Fabry therapies on FACE incidence remains unclear.MethodsThis posthoc analysis evaluated incidence of FACEs (as a composite outcome and separately for renal, cardiac and cerebrovascular events) in 97 enzyme replacement therapy (ERT)-naïve and ERT-experienced adults with Fabry disease and amenable GLA variants who were treated with migalastat for up to 8.6 years (median: 5 years) in Phase III clinical trials of migalastat. Associations between baseline characteristics and incidence of FACEs were also evaluated.ResultsDuring long-term migalastat treatment, 17 patients (17.5%) experienced 22 FACEs and there were no deaths. The incidence rate of FACEs was 48.3 events per 1000 patient-years overall. Numerically higher incidence rates were observed in men versus women, patients aged >40 years versus younger patients, ERT-naïve versus ERT-experienced patients and men with the classic phenotype versus men and women with all other phenotypes. There was no statistically significant difference in time to first FACE when analysed by patient sex, phenotype, prior treatment status or age. Lower baseline estimated glomerular filtration rate (eGFR) was associated with an increased risk of FACEs across patient populations.ConclusionsThe overall incidence of FACEs for patients during long-term treatment with migalastat compared favourably with historic reports involving ERT. Lower baseline eGFR was a significant predictor of FACEs.

Fabry disease is an X-linked lysosomal storage disorder that causes accumulation of glycosphingolipids in body tissues and fluids, leading to progressive organ damage and life-threatening complications. It can affect both males and females and can be classified into classic or later-onset phenotypes. The disease severity in females ranges from asymptomatic to the more severe, classic phenotype. Most females are hemizygous and the X-linked inheritance is associated with variable X-activation pattern and residual enzymatic activity. The heterogeneity of clinical presentation in females requires different approaches to diagnosis and management than males. A European group of 7 physicians, experienced in the management of Fabry disease, convened to discuss patient perspectives and published guidelines. The experts discussed the need to focus on psychological treatment in relation to individual coping styles when monitoring targets, and the lack of data supporting the use of plasma globotriaosylsphingosine over enzyme activity in the diagnosis of these patients. It was suggested that the high phenotypic variability in female patients may be related to the dynamic nature of the X-chromosome inactivation process and further understanding of this process could help predict the progression of Fabry disease in females and facilitate timely intervention. Due to the range of disease severity they exhibit, female patients with Fabry disease may require a more individualized treatment approach than males. Despite current recommendations, the experts agreed that early disease-specific treatment initiation in high-risk females could improve clinical outcome.

Alport syndrome inevitably leads to end-stage renal disease and there are no therapies known to improve outcome. Here we determined whether angiotensin-converting enzyme inhibitors can delay time to dialysis and improve life expectancy in three generations of Alport families. Patients were categorized by renal function at the initiation of therapy and included 33 with hematuria or microalbuminuria, 115 with proteinuria, 26 with impaired renal function, and 109 untreated relatives. Patients were followed for a period whose mean duration exceeded two decades. Untreated relatives started dialysis at a median age of 22 years. Treatment of those with impaired renal function significantly delayed dialysis to a median age of 25, while treatment of those with proteinuria delayed dialysis to a median age of 40. Significantly, no patient with hematuria or microalbuminuria advanced to renal failure so far. Sibling pairs confirmed these results, showing that earlier therapy in younger patients significantly delayed dialysis by 13 years compared to later or no therapy in older siblings. Therapy significantly improved life expectancy beyond the median age of 55 years of the no-treatment cohort. Thus, Alport syndrome is treatable with angiotensin-converting enzyme inhibition to delay renal failure and therapy improves life expectancy in a time-dependent manner. This supports the need for early diagnosis and early nephroprotective therapy in oligosymptomatic patients.

Alport syndrome results from mutations in the COL4A5 (X-linked) or COL4A3/COL4A4 (recessive) genes. This study examined 754 previously- unpublished variants in these genes from individuals referred for genetic testing in 12 accredited diagnostic laboratories worldwide, in addition to all published COL4A5, COL4A3 and COL4A4 variants in the LOVD databases. It also determined genotype-phenotype correlations for variants where clinical data were available. Individuals were referred for genetic testing where Alport syndrome was suspected clinically or on biopsy (renal failure, hearing loss, retinopathy, lamellated glomerular basement membrane), variant pathogenicity was assessed using currently-accepted criteria, and variants were examined for gene location, and age at renal failure onset. Results were compared using Fisher's exact test (DNA Stata). Altogether 754 new DNA variants were identified, an increase of 25%, predominantly in people of European background. Of the 1168 COL4A5 variants, 504 (43%) were missense mutations, 273 (23%) splicing variants, 73 (6%) nonsense mutations, 169 (14%) short deletions and 76 (7%) complex or large deletions. Only 135 of the 432 Gly residues in the collagenous sequence were substituted (31%), which means that fewer than 10% of all possible variants have been identified. Both missense and nonsense mutations in COL4A5 were not randomly distributed but more common at the 70 CpG sequences (p<10-41 and p<0.001 respectively). Gly>Ala substitutions were underrepresented in all three genes (p< 0.0001) probably because of an association with a milder phenotype. The average age at end-stage renal failure was the same for all mutations in COL4A5 (24.4 ±7.8 years), COL4A3 (23.3 ± 9.3) and COL4A4 (25.4 ± 10.3) (COL4A5 and COL4A3, p = 0.45; COL4A5 and COL4A4, p = 0.55; COL4A3 and COL4A4, p = 0.41). For COL4A5, renal failure occurred sooner with non-missense than missense variants (p<0.01). For the COL4A3 and COL4A4 genes, age at renal failure occurred sooner with two non-missense variants (p = 0.08, and p = 0.01 respectively). Thus DNA variant characteristics that predict age at renal failure appeared to be the same for all three Alport genes. Founder mutations (with the pathogenic variant in at least 5 apparently- unrelated individuals) were not necessarily associated with a milder phenotype. This study illustrates the benefits when routine diagnostic laboratories share and analyse their data.

In 1927 Arthur Cecil Alport, a South African physician, described a British family with an inherited form of kidney disease that affected males more severely than females and was sometimes associated with hearing loss. In 1961, the eponymous name Alport syndrome was adopted. In the late twentieth century three genes responsible for the disease were discovered: COL4A3, COL4A4, and COL4A5 encoding for the α3, α4, α5 polypeptide chains of type IV collagen, respectively. These chains assemble to form heterotrimers of type IV collagen in the glomerular basement membrane. Scientists, clinicians, patient representatives and their families, and pharma companies attended the 2019 International Workshop on Alport Syndrome, held in Siena, Italy, from October 22 to 26, and the 2021 online Workshop from November 30 to December 4. The main topics included: disease re-naming, acknowledging the need to identify an appropriate term able to reflect considerable clinical variability; a strategy for increasing the molecular diagnostic rate; genotype-phenotype correlation from monogenic to digenic forms; new therapeutics and new therapeutic approaches; and gene therapy using gene editing. The exceptional collaborative climate that was established in the magical medieval setting of Siena continued in the online workshop of 2021. Conditions were established for collaborations between leading experts in the sector, including patients and drug companies, with the aim of identifying a cure for Alport syndrome.

We studied here the clinical course of heterozygous carriers of X-linked Alport syndrome and a subgroup of patients with thin basement membrane disease due to heterozygous autosomal recessive Alport mutations whose prognosis may be worse than formerly thought. We analyzed 234 Alport carriers, including 29 with autosomal recessive mutations. Using Kaplan–Meier estimates and log-rank tests, autosomal and X-linked carriers were found to have similar incidences of renal replacement therapy, proteinuria, and impaired creatinine clearance. Further, age at onset of renal replacement therapy did not differ between X-chromosomal and autosomal carriers. Both groups showed an impaired life expectancy when reaching renal replacement therapy. RAAS inhibition significantly delayed the onset of end-stage renal failure. Not only carriers of X-linked Alport mutations but also heterozygous carriers of autosomal recessive mutations were found to have an increased risk for worse renal function. The risk of end-stage renal disease in both groups affected life expectancy, and this should cause a greater alertness toward patients presenting with what has been wrongly termed ‘familial benign hematuria.’ Timely therapy can help to delay onset of end-stage renal failure. Thus, yearly follow-up by a nephrologist is advised for X-linked Alport carriers and patients with thin basement membrane nephropathy, microalbuminuria, proteinuria, or hypertension.