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New sequencing technologies are revolutionizing disease gene discovery and testing with tremendous benefits for the diagnosis of rare diseases. However, the more we sequence, the more we discover, and the challenge is to assess the numerous variants in the clinical and genetic context carefully to establish the correct diagnosis. Clinicians and geneticists must work together for this because failure to do so can result in incorrect advice with potentially serious consequences.

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.

Highlights • We found a high asymptomatic rate in vulnerable people with epilepsy. • Enhanced surveillance allows to quickly contain outbreaks. • We report a low rate of COVID-19 morbidity and mortality in a long-term care facility. • Preventative measures allow reducing resident-to-resident and -to-caregiver transmission. • Children and young adults appear to have lower infection rates., In this cohort study, we aim to compare outcomes from coronavirus disease 2019 (COVID-19) in people with severe epilepsy and other co-morbidities living in long-term care facilities which all implemented early preventative measures, but different levels of surveillance. During 25-week observation period (16 March–6 September 2020), we included 404 residents (118 children), and 1643 caregivers. We compare strategies for infection prevention, control, and containment, and related outcomes, across four UK long-term care facilities. Strategies included early on-site enhancement of preventative and infection control measures, early identification and isolation of symptomatic cases, contact tracing, mass surveillance of asymptomatic cases and contacts. We measured infection rate among vulnerable people living in the facilities and their caregivers, with asymptomatic and symptomatic cases, including fatality rate. We report 38 individuals (17 residents) who tested severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-positive, with outbreaks amongst residents in two facilities. At Chalfont Centre for Epilepsy (CCE), 10/98 residents tested positive: two symptomatic (one died), eight asymptomatic on weekly enhanced surveillance; 2/275 caregivers tested positive: one symptomatic, one asymptomatic. At St Elizabeth’s (STE), 7/146 residents tested positive: four symptomatic (one died), one positive during hospital admission for symptoms unrelated to COVID-19, two asymptomatic on one-off testing of all 146 residents; 106/601 symptomatic caregivers were tested, 13 positive. In addition, during two cycles of systematically testing all asymptomatic carers, four tested positive. At The Meath (TM), 8/80 residents were symptomatic but none tested; 26/250 caregivers were tested, two positive. At Young Epilepsy (YE), 8/80 children were tested, all negative; 22/517 caregivers were tested, one positive. Infection outbreaks in long-term care facilities for vulnerable people with epilepsy can be quickly contained, but only if asymptomatic individuals are identified through enhanced surveillance at resident and caregiver level. We observed a low rate of morbidity and mortality, which confirmed that preventative measures with isolation of suspected and confirmed COVID-19 residents can reduce resident-to-resident and resident-to-caregiver transmission. Children and young adults appear to have lower infection rates. Even in people with epilepsy and multiple co-morbidities, we observed a high percentage of asymptomatic people suggesting that epilepsy-related factors (anti-seizure medications and seizures) do not necessarily lead to poor outcomes.

Context Mutations in LAMB2, encoding the basement membrane protein, laminin β2, are associated with an autosomal recessive disorder characterized by congenital nephrotic syndrome, ocular abnormalities, and neurodevelopmental delay (Pierson syndrome). Case description This report describes a 12-year-old boy with short stature, visual impairment, and developmental delay who presented with macroscopic hematuria and albuminuria. He had isolated growth hormone deficiency, optic nerve hypoplasia, and a small anterior pituitary with corpus callosum dysgenesis on his cranial magnetic resonance imaging, thereby supporting a diagnosis of optic nerve hypoplasia syndrome. Renal histopathology revealed focal segmental glomerulosclerosis. Using next-generation sequencing on a targeted gene panel for steroid-resistant nephrotic syndrome, compound heterozygous missense mutations were identified in LAMB2 (c.737G>A p.Arg246Gln, c.3982G>C p.Gly1328Arg). Immunohistochemical analysis revealed reduced glomerular laminin β2 expression compared to control kidney and a thin basement membrane on electron microscopy. Laminin β2 is expressed during pituitary development and Lamb2–/– mice exhibit stunted growth, abnormal neural retinae, and here we show, abnormal parenchyma of the anterior pituitary gland. Conclusion We propose that patients with genetically undefined optic nerve hypoplasia syndrome should be screened for albuminuria and, if present, screened for mutations in LAMB2.

International audience; Hereditary tubulopathies are rare diseases with unknown prevalence in adults. Often diagnosed in childhood, hereditary tubulopathies can nevertheless be evoked in adults. Precise diagnosis can be difficult or delayed due to insidious development of symptoms, comorbidities and polypharmacy. Here we evaluated the diagnostic value of a specific panel of known genes implicated in tubulopathies in adult patients and compared to our data obtained in children. To do this we analyzed 1033 non-related adult patients of which 744 had a clinical diagnosis of tubulopathy and 289 had a diagnosis of familial hypercalcemia with hypocalciuria recruited by three European reference centers. Three-quarters of our tubulopathies cohort included individuals with clinical suspicion of Gitelman syndrome, kidney hypophosphatemia and kidney tubular acidosis. We detected pathogenic variants in 26 different genes confirming a genetic diagnosis of tubulopathy in 29% of cases. In 16 cases (2.1%) the genetic testing changed the clinical diagnosis. The diagnosis of familial hypercalcemia with hypocalciuria was confirmed in 12% of cases. Thus, our work demonstrates the genetic origin of tubulopathies in one out of three adult patients, half of the rate observed in children. Hence, establishing a precise diagnosis is crucial for patients, in order to guide care, to survey and prevent chronic complications, and for genetic counselling. At the same time, this work enhances our understanding of complex phenotypes and enriches the database with the causal variants described.

Background and aims Gitelman syndrome (GS) is a rare renal channelopathy with an autosomal recessive type of inheritance, caused by homozygous or compound heterozygous mutations in SLC12A3 gene. The disorder causes metabolic abnormalities and may be overlapped with Barter type 3 syndrome. Methods A 7 year-old boy presented with a history of several episodes of carpopedal spasms and muscle aches in the last few months. The boy has been a relatively healthy child previously. His auxological parameters were within normal range for his sex and age. Diagnostic assessment was achieved by characteristic symptoms, imaging technics, biochemical, hormonal and molecular analyses. Results The biochemical analyses revealed hypokalemia (3.0–3.4 mmol/l), hypomagnesemia (0.64–0.66 mmol/l), hypocalciuria ( A pathogenic variants and also heterozygous for the SLC12A3 c.2944 A>T (p.Ile982Phe) likely pathogenic variant. His mother was a heterozygous for the c.2944 A>T (p.Ile982Phe) mutation, but his father was heterozygous for the other 2 variants (SLC12A3 c.1805_1806del and c.2660+1G>A). Conclusions Herein we present a first child from Macedonia with clinical manifestations and electrolyte imbalances typical for a GS. The results of the molecular analyses were consistent with the diagnosis of GS. The boy is on a high salt diet and oral potassium and magnesium supplements.

Background Inherited nephrogenic diabetes insipidus (NDI) is a rare disorder characterized by impaired urinary concentrating ability. Little clinical data on long-term outcome exists. Method This was a single-centre retrospective medical record review of patients with a diagnosis of NDI followed between 1985 and 2017. We collected available data on growth, weight, school performance, complications and comorbidities. Results We identified 36 patients with available data and a clinical diagnosis of NDI, which was genetically confirmed in 33 of them. Patients presented at a median age of 0.6 years and median length of follow-up was 9.5 years. Chief symptoms at presentation were faltering growth, vomiting/feeding concerns, polyuria/polydipsia, febrile illness and hypernatraemic dehydration. Median weight standard deviation scores (SDS) improved from −2.1 at presentation to 0.2 at last follow-up. In contrast, height SDS remained essentially unchanged at −1.1 at presentation and −0.9 at last follow-up. Most patients were treated with prostaglandin synthesis inhibitors and thiazides, yet weaned off during school age without an obvious change in urine output. Median estimated glomerular filtration rate at last follow-up was 81 mL/min/1.73 m2. Urological complications were noted in 15 patients, constipation in 11 and learning difficulties in 5. Median age at resolution of nocturnal enuresis was 11 years. Estimated median daily fluid intake at median age of 13 years was 3800 mL/m2. Conclusion The overall prognosis in inherited NDI is favourable with regular treatment. As expected, most complications were related to polyuria. There is an apparent loss of efficacy of medications during school age. Our data inform the prognosis and management of patients with NDI.

Gitelman syndrome is caused by inactivating mutations of the gene that encodes the renal sodium/chloride cotransporter (NCC; encoded by SLC12A3), resulting in hypokalemia, hypomagnesemia, hypocalciuria, and metabolic alkalosis. Renal salt wasting commonly provokes mild hypotension. The paucity of previous kidney transplants from donors with known tubulopathies suggests that such conditions may be considered contraindications to donation. A 76-year-old man received a live unrelated kidney transplant from a donor with known Gitelman syndrome secondary to a pathogenic mutation of SLC12A3. Immediate graft function preceded the emergence of the Gitelman syndrome biochemical phenotype and blood pressure subsequently improved. The recipient developed unexpected hyponatremia. Potential causes are discussed, including the possibility that it paralleled the physiologic changes seen in the high-volume state of thiazide-induced hyponatremia. Transplanted kidneys are subject to nephrotoxicity from the use of calcineurin inhibitors. Acquired Gitelman syndrome may confer a potential long-term advantage to the recipient through both improved blood pressure control and protection against the calcineurin inhibitor–induced side-effect profile caused by NCC overactivation. Both the donor and recipient remain well. In conclusion, Gitelman syndrome need not preclude kidney donation and transference of the phenotype may have benefits for the recipient.

Background The 100,000 Genomes Project is a national programme to perform whole genome sequencing (WGS) in families with an undiagnosed rare disorder or cancer. Multiple specialties from GOSH have recruited patients to the pilot study. Here we report on the outcome of the first 111 pilot cases. Methodology Total lymphocyte DNA was extracted (Chemagic Star, Chemagen) and exported to Genomics England for WGS (HiSeqX, Illumina). Prioritised variants were discussed and classified by a multidisciplinary team (MDT) of Clinical Scientists, Consultant Clinical Geneticists and the recruiting clinicians. Variants deemed to be ‘pathogenic’ or ‘likely pathogenic’ were flagged for diagnostic confirmation and clinical reporting. Results Genomics England returned results for 111 cases (probands); 95 (86%) were analysed as trios (proband and both parents). Variant interpretation has been completed for 97 cases (87%). Thirty-six percent of cases (40/111) and a total of 76 variants were discussed at an MDT meeting. Fifty-three percent of variants discussed (40/76) were classified as pathogenic or likely pathogenic, 30% (23/76) were classified as variants of unknown significance and 17% (13/76) were classified as benign or likely benign. This equated to a genetic diagnosis in 27/111 cases (25%) of which 5/111 (5%) were felt to be a partial rather than full explanation of the phenotype. Of the 97 cases where primary analysis was complete, 66/97 (68%) had no primary findings. This included cases in which variants of unknown significance have been detected. Conclusion WGS is a useful tool for rare disease diagnosis especially in patients who have undergone a fruitless diagnostic odyssey. Analysis of GOSH pilot cases has enabled us to develop infrastructure locally to support the return of main programme results. One quarter of GOSH pilot patients should expect a genetic diagnosis from the primary analysis. It is unclear whether this will be an accurate reflection of the diagnostic rate achieved in the main programme due to ongoing refinement of the recruitment and analysis pipelines.

Background: Bartter and Gitelman syndromes are autosomal recessive disorders of renal tubular salt handling. Due to their rarity, limited long-term data are available to inform prognosis and management. / Methods: Long-term longitudinal data were analysed for 45 children with pathogenic variants in SLC12A1 (n = 8), KCNJ1 (n = 8), CLCNKB (n = 17), BSND (n = 2) and SLC12A3 (n = 10) seen at a single centre between 1984 and 2014. Median follow-up was 8.9 [interquartile range (IQR) 0.7–18.1] years. / Results: Polyhydramnios and prematurity were seen in children with SLC12A1 and KCNJ1 mutations. Patients with CLCNKB mutations had the lowest serum potassium and serum magnesium and the highest serum bicarbonate levels. Fractional excretion of chloride was >0.5% in all patients prior to supplementation. Nephrocalcinosis at presentation was present in the majority of patients with SLC12A1 and KCNJ1 mutations, while it was only present in one patient with CLCNKB and not in SLC12A3 or BSND mutations. Growth was impaired, but within the normal range (median height standard deviation score −1.2 at the last follow-up). Impaired estimated glomerular filtration rate (eGFR

Background Nephrotic syndrome (NS) presenting early in life is caused by heterogeneous glomerular diseases. We retrospectively evaluated whether histological diagnosis in children presenting with NS in the first year of life predicts remission or progression to end-stage kidney disease (ESKD). Methods This is a single centre retrospective review of all children diagnosed with NS before one year of age between 1990 and 2009. All subjects had a renal biopsy, which was independently blindly reviewed by a single renal pathologist for the purpose of this study. Results Forty-nine children (25 female) who presented at 0.1–11.6 (median 1.6) months were included with 31 presenting within the first three months of life. Histopathological review diagnostic categories were; 13 Mesangial proliferative glomerulopathy (MesGN), 12 Focal and segmental glomerulosclerosis (FSGS), 11 Finnish type changes, eight Diffuse Mesangial Sclerosis (DMS), three Minimal change disease (MCD) and one each of Dense Deposit Disease (DDD) and Membranous nephropathy. Two children died from haemorrhagic complications of the biopsy. Eight children achieved remission (four MesGN, one Finnish type changes, one FSGS, one MCD and one membranous) with patient and renal survival of 73 % and 43 %, respectively, at follow-up duration of 5–222 (median 73) months (with five lost to follow-up). All children with Finnish-type histopathological changes presented within five months of age. Due to the historical nature of the cohort, genetic testing was only available for 14 children, nine of whom had an identifiable genetic basis (seven NPHS1, one PLCE1 and one ITGA3) with none of these nine children achieving remission. All of them had presented within four months of age and required renal replacement therapy, and two died. Conclusions Histopathological findings are varied in children presenting with NS early in life. Whilst groups of histological patterns of disease are associated with differing outcomes, accurate prediction of disease course in a specific case is difficult and more widespread genetic testing may improve the understanding of this group of diseases and their optimal management

Objectives To present the UK experience in genetic diagnoses of surfactant protein dysfunction disorders and develop a referral algorithm for neonates and children with persistent respiratory problems. Materials and methods Between 2006 and 2011, 427 cases were referred for surfactant mutation analyses to the North East Thames Regional Molecular Genetics Laboratory at Great Ormond Street Hospital, London. The results were reviewed and referring physicians of mutation positive cases contacted to complete a questionnaire providing clinical, radiological, histological and outcome information. Results 25 new cases were found to have genetic mutations for surfactant dysfunction disorders (7.5%), with six resulting in surfactant protein B dysfunction, seven surfactant protein C dysfunction and 12 ATP-binding cassette subfamily A member 3 (ABCA3) dysfunction. The referrals were from 15 different paediatric centres. In addition, three affected surfactant protein B (SFTPB) cases were prenatal diagnoses, following the birth of previously affected children. The majority of the confirmed cases (23 of 25) were born after 37 weeks gestation. All children with SFTPB dysfunction and the majority of ABCA3 patients presented with respiratory distress at birth. All SFTPB cases died from intractable respiratory failure. The outcome for ABCA3 mutations was variable with seven survivors. The clinical and radiological presentation of surfactant protein C (SFTPC) patients suggested mainly interstitial lung process with the majority surviving on medication. Conclusions Surfactant mutation analysis is now well established in the UK and allows better genetic diagnosis and counselling. The rarity of the condition makes it difficult to develop a validated algorithm for genetic evaluation with a need for international networking. Referrals need to be rationalised for the service to be time and cost effective.

Distal renal tubular acidosis (dRTA) is characterized by hyperchloraemic metabolic acidosis, hypokalaemia, hypercalciuria and nephrocalcinosis. It is due to reduced urinary acidification by the alpha-intercalated cells in the collecting duct and can be caused by mutations in genes that encode subunits of the vacuolar H+-ATPase (ATP6V1B1, ATP6V0A4) or the anion exchanger 1 (SLC4A1). Treatment with alkali is the mainstay of therapy. This study is an analysis of clinical data from a long-term follow-up of 24 children with dRTA in a single centre, including a genetic analysis. Of the 24 children included in the study, genetic diagnosis was confirmed in 19 patients, with six children having mutations in ATP6V1B1, ten in ATP6V0A4 and three in SLC4A1; molecular diagnosis was not available for five children. Five novel mutations were detected (2 in ATP6V1B1 and 3 in ATP6V0A4). Two-thirds of patients presented with features of proximal tubular dysfunction leading to an erroneous diagnosis of renal Fanconi syndrome. The proximal tubulopathy disappeared after resolution of acidosis, indicating the importance of following proximal tubular function to establish the correct diagnosis. Growth retardation with a height below -2 standard deviation score was found in ten patients at presentation, but persisted in only three of these children once established on alkali treatment. Sensorineural hearing loss was found in five of the six patients with an ATP6V1B1 mutation. Only one patient with an ATP6V0A4 mutation had sensorineural hearing loss during childhood. Nine children developed medullary cysts, but without apparent clinical consequences. Cyst development in this cohort was not correlated with age at therapy onset, molecular diagnosis, growth parameters or renal function. In general, the prognosis of dRTA is good in children treated with alkali.

A 2-week-old girl was transferred to our renal ward in February, 2014, from the neonatal intensive care unit of her local hospital with polyuria (200 mL/kg per day) and extreme acid–base and electrolyte disturbance that had been present from birth. She was born by spontaneous delivery at 32 weeks' gestation, after a pregnancy complicated by severe polyhydramnios necessitating two amnioreductions that had removed more than 6 L of fluid. She is the third child of consanguineous parents, with no relevant family history.