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Abstract Differentiation of hypertrophic cardiomyopathy phenotypes is challenging but crucial for appropriate management. We report a case of myocardial oxalate deposition as an infrequent cause of infiltrative cardiomyopathy.

Autosomal recessive disorders are prevalent in Pakistan, a developing South Asian country where consanguineous marriages are common. This study seeks to determine the prevalence of monogenic causes in children presenting with nephrocalcinosis and nephrolithiasis at a dialysis and transplant center in Karachi, Pakistan. A retrospective analysis was conducted in children aged 1–18 years presenting with nephrocalcinosis, between 2010 and 2019. Demographic information, clinical profile, laboratory parameters and stone analysis were collected, on a pre-designed questionnaire. One hundred and twenty-six children were included, with 11 and 3 diagnosed with renal tubular acidosis and Bartter's syndrome respectively. Next-generation sequencing and Sanger sequencing was performed on 112 children. Eighty-seven patients were diagnosed with primary hyperoxaluria, with mutations in alanine–glyoxylate-aminotransferase gene found in 73, followed by glyoxylate reductase/hydroxy-pyruvate reductase in 13, and 4-hydroxy-2-oxaloglutarate aldolase in 1. Twenty-five patients reported negative for mutations. Sixty-four percent were males, with a statistically significant difference (p < 0.05). History of parental consanguineous marriage was found in 98% of the cohort. Fifty-four and 40 patients presented to the clinic with Chronic Kidney Disease Stage 1 and Stage 5, respectively, with a statistically significant difference p = 0.007. Mutations noted in our cohort are different and more severe than those reported in the developed world. The disease poses a major disease burden in developing world context with the only treatment option of combined liver–kidney transplantation not available in Pakistan. [ABSTRACT FROM AUTHOR]

Keywords: Optical coherence tomography; optical coherence tomography angiography; primary hyperoxaluria; retinal oxalosis EN Optical coherence tomography optical coherence tomography angiography primary hyperoxaluria retinal oxalosis 2716 2720 5 07/15/22 20220701 NES 220701 Oxalate is a byproduct of normal metabolism and is excreted from the body by the kidneys through urine. Optical coherence tomography, optical coherence tomography angiography, primary hyperoxaluria, retinal oxalosis. [Extracted from the article]

Nephrocalcinosis refers to the deposits of calcium within the renal parenchyma, usually detected on ultrasonography or computed tomography. The presence of medullary nephrocalcinosis may represent a variety of different etiologies. Early childhood onset of kidney stones and/or nephrocalcinosis often represent an inherited defect more frequently than in adults. The cases reported here highlight three different diseases that were diagnosed based on genetic analysis following presentation as medullary nephrocalcinosis in childhood. [ABSTRACT FROM AUTHOR]

Primary hyperoxaluria type I is caused by an enzyme deficiency of the alanine glyoxylate-aminotransferase (AGT) which helps convert the glyoxylate to glycine. In the absence of AGT, the glyoxilate is converted to oxalate. The clinical and biological manifestations of HP1 are a direct result of the oxalate deposit in different organs (kidney, bone, blood vessels, brain, eyes...). The association of hyperoxaluria and hyperoxalemia helps establish the diagnosis of HP1 which is confirmed by the identification of a biallelic pathogenic variant of the AGXT gene, using a molecular genetic testing. Here, we report the rare case of a child suffering from renal failure of undetermined origin treated by hemodialysis, where a bone morrow biopsy, performed as part of the etiological workup of a pancytopenia, led to the diagnosis of HP1. [ABSTRACT FROM AUTHOR]

Introduction: Primary hyperoxaluria (PH) is a family of 3 rare genetic disorders of hepatic glyoxylate metabolism that lead to overproduction and increased renal excretion of oxalate resulting in progressive renal damage. LDHA inhibition of glyoxylate-to-oxalate conversion by RNA interference (RNAi) has emerged as a potential therapeutic option for all types of PH. LDHA is mainly expressed in the liver and muscles. Methods: Nonclinical data in mice and nonhuman primates show that LDHA inhibition by RNAi reduces urinary oxalate excretion and that its effects are liver-specific without an impact on off-target tissues, such as the muscles. To confirm the lack of unintended effects in humans, we analyzed data from the phase I randomized controlled trial of single-dose nedosiran, an RNAi therapy targeting hepatic LDHA. We conducted a review of the literature on LDHA deficiency in humans, which we used as a baseline to assess the effect of hepatic LDHA inhibition. Results: Based on a literature review of human LDHA deficiency, we defined the phenotype as mainly muscle-related with no liver manifestations. Healthy volunteers treated with nedosiran experienced no drug-related musculoskeletal adverse events. There were no significant alterations in plasma lactate, pyruvate, or creatine kinase levels in the nedosiran group compared with the placebo group, signaling the uninterrupted interconversion of lactate and pyruvate and normal muscle function. Conclusion: Phase I clinical data on nedosiran and published nonclinical data together provide substantial evidence that LDHA inhibition is a safe therapeutic mechanism for the treatment of all known types of PH.

The clinical manifestation of primary hyperoxaluria includes hyperoxaluria and recurrent urinary calculi. In this study, an oxidative damage model was constructed based on oxalate damage to the human renal proximal tubular epithelial cells (HK-2), and a comparative study was carried out on four different sulfated levels of Undaria pinnatifida polysaccharides (UPP0, UPP1, UPP2, and UPP3 with sulfate group [–OSO3−] contents of 1.59%, 6.03%, 20.83%, and 36.39%, respectively) on the repair of oxidatively damaged HK-2 cells. The results showed that after repair by UPPs, cell viability was enhanced, healing ability was improved, the intracellular superoxide dismutase level and mitochondrial membrane potential were increased, malondialdehyde, reactive oxygen species, and intracellular Ca2+ levels were reduced, cellular autophagy was reduced; lysosomal integrity was improved, and cytoskeleton and cell morphology were restored. The ability of repaired cells to endocytose nano-calcium oxalate dihydrate crystals (nano−COD) was enhanced. The activity of UPPs was closely related to their –OSO3− content. A too high or too low –OSO3− content was not conducive to polysaccharide activity, and only UPP2 exhibited the best cell repair ability and strongest ability to promote the cell endocytosis of crystals. UPP2 may be used as a potential agent to inhibit CaOx crystal deposition caused by high oxalate concentration.

RNA interference (RNAi) is a natural biological pathway that inhibits gene expression by targeted degradation or translational inhibition of cytoplasmic mRNA by the RNA induced silencing complex. RNAi has long been exploited in laboratory research to study the biological consequences of the reduced expression of a gene of interest. More recently RNAi has been demonstrated as a therapeutic avenue for rare metabolic diseases. This review presents an overview of the cellular RNAi machinery as well as therapeutic RNAi design and delivery. As a clinical example we present primary hyperoxaluria, an ultrarare inherited disease of increased hepatic oxalate production which leads to recurrent calcium oxalate kidney stones. In the most common form of the disease (Type 1), end‐stage kidney disease occurs in childhood or young adulthood, often necessitating combined kidney and liver transplantation. In this context we discuss nedosiran (Dicerna Pharmaceuticals, Inc.) and lumasiran (Alnylam Pharmaceuticals), which are both novel RNAi therapies for primary hyperoxaluria that selectively reduce hepatic expression of lactate dehydrogenase and glycolate oxidase respectively, reducing hepatic oxalate production and urinary oxalate levels. Finally, we consider future optimizations advances in RNAi therapies. [ABSTRACT FROM AUTHOR]

Background Primary hyperoxaluria (PH) type 3 (PH3) is caused by mutations in the hydroxy-oxo-glutarate aldolase 1 gene. PH3 patients often present with recurrent urinary stone disease in the first decade of life, but prior reports suggested PH3 may have a milder phenotype in adults. This study characterized clinical manifestations of PH3 across the decades of life in comparison with PH1 and PH2. Methods Clinical information was obtained from the Rare Kidney Stone Consortium PH Registry (PH1, n  = 384; PH2, n  = 51; PH3, n  = 62). Results PH3 patients presented with symptoms at a median of 2.7 years old compared with PH1 (4.9 years) and PH2 (5.7 years) (P = 0.14). Nephrocalcinosis was present at diagnosis in 4 (7%) PH3 patients, while 55 (89%) had stones. Median urine oxalate excretion was lowest in PH3 patients compared with PH1 and PH2 (1.1 versus 1.6 and 1.5 mmol/day/1.73 m2, respectively, P < 0.001) while urine calcium was highest in PH3 (112 versus 51 and 98 mg/day/1.73 m2 in PH1 and PH2, respectively, P < 0.001). Stone events per decade of life were similar across the age span and the three PH types. At 40 years of age, 97% of PH3 patients had not progressed to end-stage kidney disease compared with 36% PH1 and 66% PH2 patients. Conclusions Patients with all forms of PH experience lifelong stone events, often beginning in childhood. Kidney failure is common in PH1 but rare in PH3. Longer-term follow-up of larger cohorts will be important for a more complete understanding of the PH3 phenotype. [ABSTRACT FROM AUTHOR]

Supportive treatment for primary hyperoxaluria type 1 (PH1) focuses on high fluid intake and crystallization inhibitors. A subset of patients with specific PH1 genotypes (c.508G>A and c.454T>A) will respond to pyridoxine, defined as a >30% reduction in urinary oxalate excretion. Response to pyridoxine is variable and in some patients, urinary oxalate may normalize. The first focused treatment for PH1 using an RNA interference agent to reduce urinary oxalate was approved in 2020, and such therapies may significantly alter treatment approaches and long-term outcomes in PH1. Currently PH1 often presents with kidney function impairment and frequently results in end-stage kidney disease (ESKD). With kidney dysfunction, urinary oxalate clearance decreases and multisystem deposition of oxalate (oxalosis) occurs, commonly in bones, eyes, heart and skin. Once plasma oxalate levels exceed 30 µmol/L, aggressive haemodialysis is indicated to prevent oxalosis, even if the glomerular filtration rate (GFR) remains better than for typical dialysis initiation. Peritoneal dialysis alone does not achieve the needed oxalate clearance. Dialysis is a bridge to future transplantation. Liver transplantation restores hepatic alanine-glyoxylate transaminase enzyme activity, allowing glyoxylate detoxification and preventing further oxalosis. The native liver must be removed as part of this process to avoid ongoing pathologic oxalate production. The timing and type of liver transplantation are dependent on pyridoxine sensitivity, age, weight, residual GFR and evidence of systemic oxalate deposition in extrarenal organs. Liver transplant can be isolated or combined with kidney transplantation in a sequential or simultaneous fashion. Isolated kidney transplantation is generally reserved for pyridoxine-sensitive patients only. Although liver transplantation is curative for PH1 and kidney transplantation treats ESKD, ensuing necessary immunosuppression and potential allograft dysfunction impart significant long-term risks. [ABSTRACT FROM AUTHOR]

Primary hyperoxaluria type 1 (PH1) is a rare genetic form of calcium oxalate kidney stone disease. It is caused by a deficiency in the liver-specific enzyme, alanine:glyoxylate aminotransferase (AGT), a pyridoxal-5′-phosphate (PLP)-dependent enzyme involved in the metabolism of glyoxylate. The excessive endogenous synthesis of oxalate that ensues leads to hyperoxaluria, and the crystallization of the poorly soluble calcium salt of oxalate is responsible for a severe kidney stone disease, which can progress to end-stage renal disease, systemic deposition of oxalate and death. Knowledge about metabolic precursors of glyoxylate and oxalate, molecular pathology of AGT and analytical methods for diagnosis and clinical assessment have allowed a better understanding of the mechanisms underlying PH1 and opened the door to new therapeutic strategies. [ABSTRACT FROM AUTHOR]

In primary hyperoxaluria, increased hepatic oxalate production sometimes leads to severe nephrocalcinosis and early end-stage kidney disease. Oral administration of Oxalobacter formigenes (O. formigenes), an oxalate-degrading bacterium, is thought to derive oxalate from systemic sources by inducing net enteric oxalate secretion. Here, the impact of O. formigenes on nephrocalcinosis was investigated in an ethylene glycol rat model mimicking hepatic oxalate overproduction in primary hyperoxaluria. Eighteen rats were administered ethylene glycol (0.75% in drinking water) for 6 weeks, of which 9 were treated by oral gavage with O. formigenes and 9 received vehicle. Five control rats did not receive ethylene glycol or O. formigenes. Plasma and urinary oxalate levels, calcium oxalate crystalluria, urinary volume, fluid intake, and serum creatinine were monitored during the study. On killing, nephrocalcinosis was quantified. Ethylene glycol intake induced pronounced hyperoxalemia, hyperoxaluria, calcium oxalate crystalluria and nephrocalcinosis. Concomitant O. formigenes treatment partially prevented the ethylene glycol-induced increase in plasma oxalate and completely prevented nephrocalcinosis. Urinary oxalate excretion was not reduced by O. formigenes treatment. Nevertheless, absence of crystals in renal tissue of O. formigenes-treated ethylene glycol animals indicates that the propensity for oxalate to crystallize in the kidneys was reduced compared to non-treated animals. This is supported by the lower plasma oxalate concentrations in O. formigenes-treated animals. This study shows a beneficial effect of O. formigenes treatment on ethylene glycol-induced hyperoxalemia and nephrocalcinosis, and thus supports a possible beneficial effect of O. formigenes in primary hyperoxaluria. [ABSTRACT FROM AUTHOR]

Hyperoxaluria, one of the major risk factors for calcium oxalate urolithiasis and nephrocalcinosis, causes significant morbidity and mortality and should therefore be detected and treated as soon as possible. An early, consequent and adequate evaluation, but also a distinction between primary (PH) and secondary hyperoxaluria (SH) is therefore essential. We evaluated the usefulness of three consecutive 24-h urine collections under different diets [usual diet, (A), low oxalate diet, (B), high oxalate diet, (C)] to prove SH, or to find evidence of PH by changes in urinary oxalate excretion (Uox). We retrospectively analyzed results from 96 pediatric patients (47 females and 49 males, age 3–18 years) who presented with a history of nephrolithiasis, nephrocalcinosis and/or persistent hematuria in whom hyperoxaluria was found in an initial urine sample. The typical pattern of SH was found in 34 patients (mean Uox (A) 0.85 ± 0.29, (B) 0.54 ± 0.15 and (C) 0.95 ± 0.28 mmol/1.73m2/d). PH was suspected in 13 patients [(A) 1.21 ± 0.75; (B) 1.47 ± 0.51 and (C) 1.60 ± 0.82 mmol/1.73m2/d], but genetically proven only in 1/5 patients examined. No hyperoxaluria was found in 16 patients. Data were inconclusive in 33 patients. Urine collection under different diets is helpful to diagnose secondary hyperoxaluria and may provide evidence, that urinary oxalate excretion is normal. We have now established this procedure as our first diagnostic step before further, more extensive and more expensive evaluations are performed. [ABSTRACT FROM AUTHOR]

Abstract Primary hyperoxaluria (PH) is a group of diseases due to mutations in genes coding for enzymes involved in oxalate metabolism. Three types of PH are identified depending on the gene mutated. Type 1 is the most frequent with 80% of the cases, while PH2 and PH3 are rarer. The severity of renal involvement varies between the three types. Indeed, between 60% and 80% of PH1 but only 20% of PH2 patients will reach end‐stage kidney disease. In PH3 patients, dialysis is uncommon. Because oxalate clearance is impaired in CKD patients, oxalate can precipitate in various organs leading to systemic oxalosis. We report an uncommon presentation of bone oxalosis associated with hypercalcemia in a dialyzed patient. This report emphasizes the difficulties to diagnose primary hyperoxaluria and the challenge of treating dialyzed patients.

Primary hyperoxaluria type I (PH1) is caused by AGXT gene mutations that decrease the functional activity of alanine:glyoxylate aminotransferase. A build-up of the enzyme’s substrate, glyoxylate, results in excessive deposition of calcium oxalate crystals in the renal tract, leading to debilitating renal failure. Oxidation of glycolate by glycolate oxidase (or hydroxy acid oxidase 1, HAO1) is a major cellular source of glyoxylate, and siRNA studies have shown phenotypic rescue of PH1 by the knockdown of HAO1, representing a promising inhibitor target. Here, we report the discovery and optimization of six low-molecular-weight fragments, identified by crystallography-based fragment screening, that bind to two different sites on the HAO1 structure: at the active site and an allosteric pocket above the active site. The active site fragments expand known scaffolds for substrate-mimetic inhibitors to include more chemically attractive molecules. The allosteric fragments represent the first report of non-orthosteric inhibition of any hydroxy acid oxidase and hold significant promise for improving inhibitor selectivity. The fragment hits were verified to bind and inhibit HAO1 in solution by fluorescence-based activity assay and surface plasmon resonance. Further optimization cycle by crystallography and biophysical assays have generated two hit compounds of micromolar (44 and 158 µM) potency that do not compete with the substrate and provide attractive starting points for the development of potent and selective HAO1 inhibitors.

Primary hyperoxaluria (PH) is a rare autosomal recessive metabolic disorder where serum oxalate levels rise due to overproduction. The kidney tubule is a main target for oxalate deposition, resulting in damage to the organ. Kidney failure is rare in these patients. We present a 67-year-old female with hemodialysis-dependent end-stage renal disease likely due to PH type 2 or 3. With extremely high levels of serum oxalate (60.4 μmol/L), this patient had minimal treatment options for her rare disease. This report details a unique presentation of a rare disease where kidney biopsy was instrumental.

Abstract Background Primary hyperoxaluria (PH) is an inherited disease lacking of hepatic oxalic acid metabolic enzymes which could lead to irreverisible renal damage. Currently, liver–kidney transplantation is a curative but highly invasive therapy used to treat patients with PH. However, limited studies have focused on combined liver–kidney transplantation (CLKT) and sequential liver and kidney transplantation (SLKT) in patients with PH. Methods The present study included 201 patients with PH who received both liver and kidney transplants and who were listed on the Scientific Registry of Transplant Recipients from 1987 to 2018. According to the liver–kidney transplant procedure, patients were separated into a CLKT group and a SLKT group. Patient demographics and transplant outcomes were assessed in each group. Results Compared with the SLKT group, The CLKT group got a worse pretransplant dialysis condition in both the proportion of patients under pretransplant dialysis (p = 0.048) and the duration of the pretransplant dialysis (p

Abstract Background Patients with primary hyperoxaluria (PH) often develop kidney stones and chronic kidney disease. Noninvasive urine markers reflective of active kidney injury could be useful to gauge the effectiveness of ongoing treatments. Methods A panel of biomarkers that reflect different nephron sites and potential mechanisms of injury (clusterin, neutrophil gelatinase-associated lipocalin (NGAL), 8-isoprostane (8IP), monocyte-chemoattractant protein 1(MCP-1), liver-type fatty acid binding protein (L-FABP), heart-type fatty acid binding protein (H-FABP), and osteopontin (OPN)) were measured in 114 urine specimens from 30 PH patients over multiple visits. Generalized estimating equations were used to assess associations between biomarkers and 24 h urine excretions, calculated proximal tubular oxalate concentration (PTOx), and eGFR. Results Mean (±SD) age at first visit was 19.5 ± 16.6 years with an estimated glomerular filtration rate (eGFR) of 68.4 ± 21.0 ml/min/1.73m2. After adjustment for age, sex, and eGFR, a higher urine MCP-1 concentration and MCP-1/creatinine ratio was positively associated with CaOx supersaturation (SS). Higher urine NGAL and NGAL/creatinine as well as OPN and OPN/creatinine were associated with higher eGFR. 8IP was negatively associated with PTOx and urinary Ox, but positively associated with CaOx SS. Conclusion In PH patients greater urine MCP-1 and 8IP excretion might reflect ongoing collecting tubule crystallization, while greater NGAL and OPN excretion may reflect preservation of kidney mass and function. CaOx crystals, rather than oxalate ion may mediate oxidative stress in hyperoxaluric conditions. Further studies are warranted to determine whether urine MCP-1 excretion predicts long term outcome or is altered in response to treatment.

Background: Primary hyperoxaluria type 1 (PH1) is a rare genetic disease caused by hepatic overproduction of oxalate, ultimately responsible for kidney stones, kidney failure and systemic oxalosis. Lumasiran, is a liver-directed RNA interference therapeutic agent. It has been shown to reduce hepatic oxalate production by targeting glycolate oxidase, and to dramatically reduce oxalate excretion.Care Report: We present the case of a teenager patient affected by PH1, who entered in the lumasiran compassionate use program. The patient had a rapid and sustained decrease in urinary oxalate/creatinine ratio, with a mean reduction after lumasiran administration of about 70%. During the 18 months long follow-up, urinary oxalate remained low, reaching nearly normal values. Plasma oxalate also decreased dramatically. Normal levels were reached immediately after the first dose and remained consistently low thereafter. During the same follow-up period, eGFR remained stable at about 60 ml/min/1.73 m2, but no new kidney stones were observed. Existing kidney stones did not increase in size. The patient did not suffer renal colic events and did not require further urological interventions.Conclusion: In our severely affected PH1 patient, lumasiran proved to be very effective in rapidly and consistently reducing plasma oxalate and urinary excretion to normal and near-normal levels, respectively. In the 18 months long follow-up post-lumasiran, the eGFR remained stable and the patient showed clinical improvements. As far as we know, this report covers the longest observation period after initiation of this novel RNAi therapy.

Glycolate oxidase (HAO1) catalyses the synthesis of glyoxylate, a common metabolic intermediate that causes renal failure if accumulated. HAO1 inhibition is an emerging treatment for primary hyperoxaluria, a rare disorder of glyoxylate metabolism. Here we report the first cell-based measurement of inhibitor uptake and engagement with HAO1, by adapting the cellular thermal shift assay (CETSA) based on Nano luciferase complementation and luminescence readout. By profiling the interaction between HAO1 and four well-characterised inhibitors in intact and lysed HEK293T cells, we showed that our CETSA method differentiates between low-permeability/high-engagement and high-permeability/low-engagement ligands and is able to rank HAO1 inhibitors in line with both recombinant protein methods and previously reported indirect cellular assays. Our methodology addresses the unmet need for a robust, sensitive, and scalable cellular assay to guide HAO1 inhibitor development and, in broader terms, can be rapidly adapted for other targets to simultaneously monitor compound affinity and cellular permeability., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Introduction: Primary hyperoxaluria type 1 (PH1) is known for its variable clinical course, even within families. However, the extent of this heterogeneity has not been well-studied. We aimed to analyze intrafamilial clinical heterogeneity and disease course among siblings in a large cohort of familial PH1 cases., Methods: A retrospective registry study was performed using data from OxalEurope. All PH1 families with 2 or more affected siblings were included. A 6-point PH1 clinical outcome scoring system was developed to grade heterogeneity within a family. Intrafamilial clinical heterogeneity was defined as a score ≥2. Kaplan-Meier analyses were used to analyze differences in kidney survival between index cases and siblings., Results: We included 88 families, encompassing 193 patients with PH1. The median interquartile range (IQR) follow-up time was 7.8 (1.9-17) years. Intrafamilial clinical heterogeneity, as defined by our score, was found in 38 (43%) PH1 families. In 54% of the families, affected siblings had a better outcome than the index case. Clinically asymptomatic siblings at the time of their diagnosis had a significantly more favorable clinical outcome based on the authors' scoring system than siblings with clinical signs and index cases ( P  < 0.001). Kaplan-Meier analyses revealed that index cases reached kidney failure at an earlier age and earlier in follow-up compared to siblings ( P  < 0.001)., Conclusions: Intrafamilial clinical heterogeneity was found in a substantial number of familial PH1 cases. Compared to index cases, siblings had significantly better clinical outcomes and kidney survival; thereby supporting the policy of family screening to diagnose affected siblings early to improve their prognosis., (© 2024 International Society of Nephrology. Published by Elsevier Inc.)

Background: Primary hyperoxaluria (PH) is a rare inherited autosomal recessive disease caused by disturbed glyoxylate metabolism. The disease is characterized by calcium oxalate crystal deposition in various organs, especially in the kidney. Due to the lack of current understanding of PH, nearly all patients are only initially diagnosed with PH when recurrent lithiasis and progressive end-stage renal disease occur. Many cases are not diagnosed in patients until renal allograft insufficiency occurs after renal transplantation. This case report and literature review aim to emphasize the need for careful pre-transplant PH screening of patients with bilateral nephrocalcinosis or nephrolithiasis.Case Presentation: Renal allograft insufficiency was diagnosed as PH after kidney transplantation. Here, we detail the complete clinical course, including computed tomography images of the original kidney and renal graft, histopathological images of a biopsy of the transplanted kidney, the results of laboratory and molecular genetic tests, and the treatment. In addition, we reviewed the literature from 2000 to 2021 and analyzed 19 reported cases of PH diagnosed after kidney transplantation, and provide a summary of the characteristics, complications, treatment, and prognosis of these cases.Conclusions: By reviewing and analyzing these cases, we concluded that patients with a history of nephrocalcinosis or nephrolithiasis in both kidneys need preoperative screening for PH and appropriate treatment before kidney transplantation. Delayed graft function caused by PH is easily misdiagnosed as acute rejection, and needle biopsy should be performed at an early stage. [ABSTRACT FROM AUTHOR]

Background: Systemic oxalosis is a severe complication seen in primary hyperoxaluria type I patients with kidney failure. Deposition of insoluble calcium oxalate crystals in multiple organs leads to significant morbidity and mortality. Methods: We describe a retrospective cohort of 11 patients with systemic oxalosis treated at our dialysis unit from 1982 to 1998 (group 1) and 2007–2019 (group 2). Clinical and demographic data were collected from medical records. Imaging studies were only available for patients in group 2 (n = 5). Results: Median age at dialysis initiation was 6.1 months (IQR 4–21.6), 64% were male. Dialysis modality was mostly peritoneal dialysis in group 1 and daily hemodialysis in group 2. Bone disease was the first manifestation of systemic oxalosis, starting with the appearance of sclerotic bands (mean 166 days, range 1–235), followed by pathological fractures in long bones (mean 200.4 days, range 173–235 days). Advanced disease was characterized by vertebral fractures with resulting kyphosis, worsening splenomegaly, and adynamic bone disease. Two patients developed pulmonary hypertension, 4 and 8 months prior to their death. Four of 11 patients developed hypothyroidism 0–60 months after dialysis initiation. Only one patient survived after a successful liver–kidney transplantation. Four patients died after liver or liver–kidney transplantation. Conclusions: This is the first comprehensive description of the natural history of pediatric systemic oxalosis. We hope that our findings will provide basis for a quantitative severity score in future, larger studies. [ABSTRACT FROM AUTHOR]

Primary hyperoxaluria (PH) type 1 is a rare hereditary metabolic disorder resulting in accumulation of calcium oxalate in several organs, including the heart. Cardiac oxalosis in PH is poorly described in the medical literature. We report the case of a 42-year-old woman diagnosed with primary hyperoxaluria type 1 and end-stage renal failure who presented with syncope related to a paroxysmal third-degree atrioventricular block. The patient benefited from the implantation of a dual chamber pacemaker with a good outcome. Conduction blocks in case of primary hyperoxaluria type 1 are exceptional; in fact, less than five reports have previously been published in the medical literature. With this case, we would like to highlight the need for regular and careful monitoring of cardiac status in patients treated for primary oxalosis, especially when renal function is impaired.

Loss-of-function mutations in three genes, involved in the metabolic pathway of glyoxylate, result in increased oxalate production and its crystallization in the form of calcium oxalate. This leads to three forms of primary hyperoxaluria—an early-onset inherited kidney disease with wide phenotypic variability ranging from isolated kidney stone events to stage 5 chronic kidney disease in infancy. This review provides a description of metabolic processes resulting in oxalate overproduction and summarizes basic therapeutic approaches. Unfortunately, current treatment of primary hyperoxaluria does not allow the prevention of loss of kidney function or to substantially diminish other symptoms in most patients. However, latest breakthroughs in biotechnology provide new promising directions for drug development. Some of them have already progressed to the level of clinical trials; others are just at the stage of proof of concept. Here we review the most advanced technologies including those that have been harnessed as possible therapeutic modalities. [ABSTRACT FROM AUTHOR]

Background: Primary hyperoxaluria type 1 (PH1) is characterized by hepatic overproduction of oxalate and often results in kidney failure. Liver-kidney transplantation is recommended, either combined (CLKT) or sequentially performed (SLKT). The merits of SLKT and the place of an isolated kidney transplant (KT) in selected patients are unsettled. We systematically reviewed the literature focusing on patient and graft survival rates in relation to the chosen transplant strategy. Methods: We searched MEDLINE and Embase using a broad search string, consisting of the terms 'transplantation' and 'hyperoxaluria'. Studies reporting on at least four transplanted patients were selected for quality assessment and data extraction. Results: We found 51 observational studies from 1975 to 2020, covering 756 CLKT, 405 KT and 89 SLKT, and 51 pre-emptive liver transplantations (PLT). Meta-analysis was impossible due to reported survival probabilities with varying follow-up. Two individual high-quality studies showed an evident kidney graft survival advantage for CLKT versus KT (87% vs. 14% at 15 years, p<0.05) with adjusted HR for graft failure of 0.14 (95% confidence interval: 0.05–0.41), while patient survival was similar. Three other high-quality studies reported 5-year kidney graft survival rates of 48–89% for CLKT and 14–45% for KT. PLT and SLKT yielded 1-year patient and graft survival rates up to 100% in small cohorts. Conclusions: Our study suggests that CLKT leads to superior kidney graft survival compared to KT. However, evidence for merits of SLKT or for KT in pyridoxine-responsive patients was scarce, which warrants further studies, ideally using data from a large international registry. [ABSTRACT FROM AUTHOR]

Background: In patients with primary hyperoxaluria (PH), endogenous oxalate overproduction increases urinary oxalate excretion, leading to compromised kidney function and often kidney failure. Highly elevated plasma oxalate (Pox) is associated with systemic oxalate deposition in patients with PH and severe chronic kidney disease (CKD). The relationship between Pox and estimated glomerular filtration rate (eGFR) in patients with preserved kidney function, however, is not well established. Our analysis aimed to investigate a potential correlation between these parameters in PH patients from three randomized, placebo-controlled trials (studies OC3-DB-01, OC3-DB-02, and OC5-DB-01). Methods: Baseline data from patients with a PH diagnosis (type 1, 2, or 3) and eGFR > 40 mL/min/1.73 m2 were analyzed for a correlation between eGFR and Pox using Spearman's rank and Pearson's correlation coefficients. Data were analyzed by individual study and additionally were pooled for Studies OC3-DB-02 and OC5-DB-01 in which the same Pox assay was used. Results: A total of 106 patients were analyzed. A statistically significant inverse Spearman's correlation between eGFR and Pox was observed across all analyses; correlation coefficients were − 0.44 in study OC3-DB-01, − 0.55 in study OC3-DB-02, − 0.51 in study OC5-DB-01, and − 0.49 in the pooled studies (p < 0.0064). Conclusions: Baseline evaluations showed a moderate and statistically significant inverse correlation between eGFR and Pox in patients with PH already at early stages of CKD (stages 1–3b), demonstrating that a correlation is present before substantial loss in kidney function occurs. [ABSTRACT FROM AUTHOR]

Primary hyperoxaluria type 1 is a rare genetic condition characterized by oxalate deposition in the kidneys. We report findings of an 8-month old female presenting with failure to thrive, poor oral intake, and kidney stones resulting in the diagnosis of primary hyperoxaluria type 1. The patient exhibits a unique presentation without renal failure at the time of diagnosis suggesting a previously unreported comorbidity in early stages of disease.

Background Primary hyperoxaluria (PH), a rare inborn error of glyoxylate meta bolism causing overproduction of oxalate, is classified into three genetic subgroups: type 1–3 (PH1–PH3) caused by AGXT, GRHPR, and HOGA1 gene mutations, respectively. We performed a retrospective case series study of Korean pediatric patients with PH. Methods In total, 11 unrelated pediatric patients were recruited and their phenotypes and genotypes were analyzed by a retrospective review of their medical records. Results Mutational analyses revealed biallelic AGXT mutations (PH1) in nine patients and a single heterozygous GRHPR and HOGA1 mutation in one patient each. The c.33dupC was the most common AGXT mutation with an allelic frequency of 44%. The median age of onset was 3 months (range, 2 months–3 years), and eight patients with PH1 presented with end stage renal disease (ESRD). Patients with two truncating mutations showed an earlier age of onset and more frequent retinal involvement than patients with one truncating mutation. Among eight PH1 patients presenting with ESRD, five patients were treated with intensive dialysis followed by liver transplantation (n=5) with/without subsequent kidney transplantation (n=3). Conclusion Most patients presented with severe infantile forms of PH. Patients with two truncating mutations displayed more severe phenotypes than those of patients with one truncating mutation. Sequential liver and kidney transplantation was adopted for PH1 patients presenting with ESRD. A larger nation-wide multicenter study is needed to confirm the genotype-phenotype correlations and outcomes of organ transplantation.

Abstract Background Primary hyperoxaluria (PH) is a rare inborn disorder of the metabolism of glyoxylate, which causes the hallmark production oxalate and forms insoluble calcium oxalate crystals that accumulate in the kidney and other organs. Since the manifestation of PH varies from recurrent nephrolithiasis, nephrocalcinosis, and end-stage renal disease with age at onset of symptoms ranging from infancy to the sixth decade, the disease remains undiagnosed until after kidney transplantation in some cases. Case presentation Herein, we report 3 cases of PH diagnosed after kidney transplantation failure, providing the comprehensive clinical course, the ultrasonic image of renal graft and pathologic image of the biopsy, highlighting the relevance of biopsy findings and the results of molecular genetic testing. We also focus on the treatment and the unfavorable outcome of the patients. Meanwhile, we review the literature and show the additional 10 reported cases of PH diagnosed after kidney transplantation. Additionally, we discuss the progressive molecular understanding of the mechanisms involved in PH and molecular therapy. Conclusions Overall, the necessity of preoperative screening of PH in all patients even with a minor history of nephrolithiasis and the importance of proper treatment are the lessons we learn from the 3 cases, which prompt us to avoid tragedies.

Background: Primary hyperoxaluria type 1 (PH1) is a rare monogenic disorder characterized by excessive hepatic production of oxalate leading to recurrent nephrolithiasis, nephrocalcinosis, and progressive kidney damage, often requiring renal replacement therapy (RRT). Though systemic oxalate deposition is well-known, the natural history of PH1 during RRT has not been systematically described. In this study, we describe the clinical, laboratory, and echocardiographic features of a cohort of PH1 patients on RRT.Methods: Patients with PH1 enrolled in the Rare Kidney Stone Consortium PH Registry who progressed to require RRT, had ≥2 plasma oxalate (pOx) measurements 3–36 months after start of RRT, and at least one pair of pOx measurements between 6 and 18 months apart were retrospectively analyzed. Clinical, echocardiographic, and laboratory results were obtained from the Registry.Results: The 17 PH1 patients in our cohort had a mean total HD hours/week of 17.4 (SD 7.9; range 7.5–36) and a range of age of RRT start of 0.2–75.9 years. The average change in plasma oxalate (pOx) over time on RRT was −0.74 [−2.9, 1.4] μmol/L/month with the mean pOx never declining below 50 μmol/L. Over time on RRT, oxalosis progressively developed in multiple organ systems. Echocardiography performed on 13 subjects showed worsening of left ventricular global longitudinal strain correlated with pOx (p < 0.05).Conclusions: Even when a cohort of PH1 patients were treated with intensified RRT, their predialysis pOx remained above target and they developed increasing evidence of oxalosis. Echocardiographic data suggest that cardiac dysfunction could be related to elevated pOx and may worsen over time.

Les hyperoxaluries primitives sont transmises sur le mode autosomique récessif ; il s'agit d'affections rares, engageant souvent le pronostic rénal et parfois le pronostic vital, notamment dans les formes à début précoce. Il existe trois types, répondant à des déficits enzymatiques distincts. Le type 1 représente 85 % des cas et résulte d'un déficit enzymatique (alanine-glyoxylate aminotransférase) au niveau des peroxysomes du foie, à l'origine d'une hyperoxalurie qui s'exprime initialement par des lithiases avec ou sans néphrocalcinose. Au fur et à mesure que la filtration glomérulaire diminue, une surcharge systémique apparaît et n'épargne aucun organe. Le traitement repose jusque-là sur la transplantation combinée hépatique et rénale, avec une mortalité et une morbidité non négligeables. L'introduction récente de traitements par ARN interférent ouvre de nouvelles perspectives. En bloquant une synthèse enzymatique (glycolate-oxydase ou lacticodéshydrogénase a) en amont du déficit qui provoque la maladie, l'oxalurie se normalise et la tolérance du produit (administré par voie injectable tous les 1 à 3 mois) est bonne. Cette stratégie va permettre d'éviter l'insuffisance rénale chez les patients traités précocement et d'éviter la transplantation hépatique chez ceux dont le diagnostic aura été fait à un stade avancé de l'insuffisance rénale. Primary hyperoxalurias are rare disease with autosomal recessive inheritance; they often lead to kidney failure and can lead to life-threatening conditions, especially in early onset forms. There are three types, responding to distinct enzyme deficits. Type 1 represents 85% of cases and results from an enzyme deficiency (alanine-glyoxylate aminotransferase) in the peroxisomes of the liver, causing hyperoxaluria leading to urolithiasis with or without nephrocalcinosis. As glomerular filtration decreases, a systemic overload appears and spares no organ. Treatment has hitherto been based on combined liver and kidney transplantation, with significant mortality and morbidity. The recent introduction of interfering RNA treatments opens up new perspectives. By blocking an enzymatic synthesis (glycolate oxidase or lacticodehydrogenase a) upstream of the deficit that causes the disease, oxaluria normalizes and the tolerance of the drug (administered by injection every 1 to 3 months) is good. This strategy will help prevent kidney failure in patients treated early and avoid liver transplantation in those who are diagnosed at an advanced stage of kidney failure. [ABSTRACT FROM AUTHOR]

We report the case of a 31-year-old female with primary hyperoxaluria type 1 with end-stage kidney disease who developed severe peripheral vascular disease leading to limb amputation initially thought to be secondary to calciphylaxis. However, polarized review of the pathologic specimen revealed calcium oxalate deposition in the lumen of blood vessels. This unusual presentation of systemic oxalosis demonstrates the adverse consequences of elevations of serum oxalate in patients with hyperoxaluria and that levels can acutely worsen with abrupt onset of kidney failure. [ABSTRACT FROM AUTHOR]