Monoallelic pathogenic ALG5 variants cause atypical polycystic kidney disease and interstitial fibrosis.

Disorders of the autosomal dominant polycystic kidney disease (ADPKD) spectrum are characterized by the development of kidney cysts and progressive kidney function decline. PKD1 and PKD2, encoding polycystin (PC)1 and 2, are the two major genes associated with ADPKD; other genes include IFT140, GANAB, DNAJB11, and ALG9. Genetic testing remains inconclusive in ∼7% of the families. We performed whole-exome sequencing in a large multiplex genetically unresolved (GUR) family affected by ADPKD-like symptoms and identified a monoallelic frameshift variant (c.703_704delCA) in ALG5. ALG5 encodes an endoplasmic-reticulum-resident enzyme required for addition of glucose molecules to the assembling N-glycan precursors. To identify additional families, we screened a cohort of 1,213 families with ADPKD-like and/or autosomal-dominant tubulointerstitial kidney diseases (ADTKD), GUR (n = 137) or naive to genetic testing (n = 1,076), by targeted massively parallel sequencing, and we accessed Genomics England 100,000 Genomes Project data. Four additional families with pathogenic variants in ALG5 were identified. Clinical presentation was consistent in the 23 affected members, with non-enlarged cystic kidneys and few or no liver cysts; 8 subjects reached end-stage kidney disease from 62 to 91 years of age. We demonstrate that ALG5 haploinsufficiency is sufficient to alter the synthesis of the N-glycan chain in renal epithelial cells. We also show that ALG5 is required for PC1 maturation and membrane and ciliary localization and that heterozygous loss of ALG5 affects PC1 maturation. Overall, our results indicate that monoallelic variants of ALG5 lead to a disorder of the ADPKD-spectrum characterized by multiple small kidney cysts, progressive interstitial fibrosis, and kidney function decline.

Association between daily haemodialysis, access to renal transplantation and patients' survival in France.

AIM: Daily haemodialysis improves patients' quality of life and blood purification, but its effect on survival remains controversial. The aim of this study was to analyze the association between daily haemodialysis and renal transplantation and survival in France. METHODS: This was an observational cohort study based on the French REIN registry. All incident patients ≥18 years old who started daily haemodialysis in France between 2003 and 2012 were included. Using a propensity score, 575 patients on daily haemodialysis were matched with 1696 patients receiving thrice-weekly haemodialysis. Survival analysis was performed using the Cox model. Access to the renal transplant waiting list and renal transplantation were analyzed using the Fine and Gray model. RESULTS: Daily haemodialysis was not independently associated with reduced access to transplant waiting list, whereas, major comorbidities remained associated with restricted waitlisting after multivariate analysis adjusted for confounding factors. After being waitlisted, the cumulative incidence of renal transplantation was lower for the daily haemodialysis than for the thrice-weekly haemodialysis group (SHR = 0.72, 95%CI: 0.56-0.91). The risk of death was significantly higher in the daily haemodialysis group (HRadjusted  = 1.58, 95%CI: 1.4-1.8). Major comorbidities were associated with higher risk of death and lower likelihood of receiving a renal transplant during the follow-up period. CONCLUSION: Our study showed that in France, the likelihood of undergoing renal transplantation after being waitlisted was lower for patients on daily haemodialysis than those on thrice-weekly haemodialysis. Moreover, daily haemodialysis was associated with higher risk of death, even after taking into account age and all major comorbidities.

Renal replacement therapy for rare diseases affecting the kidney: an analysis of the ERA-EDTA Registry.

BACKGROUND: In recent years, increased efforts have been undertaken to address the needs of patients with rare diseases by international initiatives and consortia devoted to rare disease research and management. However, information on the overall prevalence of rare diseases within the end-stage renal disease (ESRD) population is limited. The aims of this study were (i) to identify those rare diseases within the ERA-EDTA Registry for which renal replacement therapy (RRT) is being provided and (ii) to determine the prevalence and incidence of RRT for ESRD due to rare diseases, both overall and separately for children and adults. METHODS: The Orphanet classification of rare disease was searched for rare diseases potentially causing ESRD, and these diagnosis codes were mapped to the corresponding ERA-EDTA primary renal disease codes. Thirty-one diagnoses were defined as rare diseases causing ESRD. RESULTS: From 1 January 2007 to 31 December 2011, 7194 patients started RRT for a rare disease (10.6% children). While some diseases were exclusively found in adults (e.g. Fabry disease), primary oxalosis, cystinosis, congenital anomalies of the kidney and urinary tract (CAKUT) and medullary cystic kidney disease affected young patients in up to 46%. On 31 December 2011, 20 595 patients (12.4% of the total RRT population) were on RRT for ESRD caused by a rare disease. The point prevalence was 32.5 per million age-related population in children and 152.0 in adults. Only 5.8% of these patients were younger than 20 years; however, 57.7% of all children on RRT had a rare disease, compared with only 11.9% in adults. CAKUT and focal segmental glomerulosclerosis were the most prevalent rare disease entities among patients on RRT. CONCLUSIONS: More than half of all children and one of nine adults on RRT in the ERA-EDTA Registry suffer from kidney failure due to a rare disease, potentially with a large number of additional undiagnosed or miscoded cases. Comprehensive diagnostic assessment and the application of accurate disease classification systems are essential for improving the identification and management of patients with rare kidney diseases.

[Psychological impact of lockdown and the COVID-19 epidemic on haemodialysis patients and carers in France]. / Répercussions psychologiques du confinement et de l'épidémie à COVID-19 chez les patients et soignants en hémodialyse en France.

INTRODUCTION: The health crisis linked to the COVID-19 epidemic has required lockdown measures in France and changes in practices in dialysis centers. The objective was to assess the depressive and anxiety symptoms during lockdown in hemodialysis patients and their caregivers. METHODS: We sent, during lockdown period, between April and May 2020, self-questionnaires to voluntary subjects (patients and caregivers), treated by hemodialysis or who worked in hemodialysis in one of the 14 participating centers in France. We analyzed their perception of dialysis sessions (beneficial or worrying), their stress level (VAS rated from 0 to 10), their anxiety and depressive symptoms (Hospital anxiety and depression scale). Factors associated with stress, anxiety and depression were analyzed with multiple linear regression models. RESULTS: 669 patients and 325 caregivers agreed to participate. 70 % of participants found it beneficial to come to dialysis during confinement. The proportions of subjects with a stress level ≥ 6 linked to the epidemic, confinement, fear of contracting COVID-19 and fear of infecting a loved one were respectively 23.9%, 26.2%, 33.4% and 42%. 39.2% presented with certain (13.7%) or doubtful (19.2%) anxious symptoms. 21.2% presented a certain (7.9%) or doubtful (13.3%) depressive symptomatology. Age, gender, history of psychological disorders and perception of dialysis sessions were associated with levels of stress, anxiety and depression. CONCLUSION: During the lockdown period, in France, the majority of hemodialysis patients and caregivers found it beneficial to come to dialysis. One in three subjects had anxiety symptoms and one in five subjects had depressive symptoms.