Efficacy and safety of lumasiran for infants and young children with primary hyperoxaluria type 1: 30-month analysis of the phase 3 ILLUMINATE-B trial.

Background: Primary hyperoxaluria type 1 (PH1) is a genetic disorder resulting in overproduction of hepatic oxalate, potentially leading to recurrent kidney stones, nephrocalcinosis, chronic kidney disease, and kidney failure. Lumasiran, the first RNA interference therapeutic approved for infants and young children, is a liver-directed treatment that reduces hepatic oxalate production. Lumasiran demonstrated sustained efficacy with an acceptable safety profile over 12 months in infants and young children (age <6 years) with PH1 in ILLUMINATE-B (clinicaltrials.gov: NCT03905694), an ongoing, Phase 3, multinational, open-label, single-arm study. Methods: Here, we report interim efficacy and safety findings from ILLUMINATE-B following 30 months of lumasiran treatment. Eligible patients had an estimated glomerular filtration rate (eGFR) >45 ml/min/1.73 m2 if ≥12 months old or normal serum creatinine if <12 months old, and a urinary oxalate to creatinine ratio (UOx:Cr) greater than the upper limit of normal. All 18 patients enrolled in ILLUMINATE-B completed the 6-month primary analysis period, entered an extension period of up to 54 months, and continue to participate in the study. Results: At Month 30, mean percent change from baseline in spot UOx:Cr was -76%, and mean percent change in plasma oxalate was -42%. eGFR remained stable through Month 30. In 14 patients (86%) with nephrocalcinosis at baseline, nephrocalcinosis grade improved at Month 24 in 12; no patient worsened. In the 4 patients without baseline nephrocalcinosis, nephrocalcinosis was absent at Month 24. Kidney stone event rates were ≤0.25 per person-year through Month 30. Mild, transient injection site reactions were the most common lumasiran-related adverse events (17% of patients). Conclusion: In infants and young children with PH1, long-term lumasiran treatment resulted in sustained reductions in urinary and plasma oxalate that were sustained for 30 months, with an acceptable safety profile. Kidney function remained stable, low kidney stone event rates were observed through Month 30, and nephrocalcinosis grade improvements were observed through Month 24. Clinical Trial Registration: https://clinicaltrials.gov, identifier NCT03905694.

Late-onset retinal oxalosis in primary hyperoxaluria type 2.

Purpose: To report a previously undescribed case of late-onset vision loss due to retinal oxalosis in a patient with primary hyperoxaluria type 2 (PH2). Observations: An 82-year-old female with a history of biopsy-proven oxalate nephropathy developed vision loss 8 months after end stage kidney disease. She developed progressive retinal ischemia secondary to crystal deposition. She was presumed to have retinal oxalosis, and genetic testing confirmed PH2. Her retinopathy occurred once renal clearance fellow below hepatic oxalate production. The only effective treatment is kidney transplantation, but this patient was not a candidate. Conclusions and Importance: To date, this is the most delayed-onset and severe reported case of progressive ischemic retinopathy from PH2. Patients with systemic oxalosis should be referred for genetic testing, as there are new RNA interference treatments approved for other subtypes of primary hyperoxaluria.

Infant primary hyperoxaluria type 1: A case report and literature review. / å©´å„¿åŽŸå‘æ€§é«˜è‰é ¸å°¿ç—‡1型1ä¾‹å¹¶æ–‡çŒ®å¤ä¹ .

Primary hyperoxaluria (PH) is a rare autosomal recessive disorder, with PH type 1 (PH1) being the most common. It is primarily characterized by recurrent renal calculi, renal calcification, and can lead to acute renal failure. In infants, PH1 often results in early end-stage renal disease (ESRD) with a high mortality rate. This paper reports a case of an infant with acute renal failure in the Second Hospital of Shandong University who was diagnosed as PH1 using whole-exome sequencing, revealing a homozygous mutation in the AGXT gene (c.596-2A>G), which is reported here for the first time in the Chinese population. Previous literature indicates that urinary oxalate levels and stone composition can suggest PH1, with the gold standard for diagnosis being liver biopsy combined with alanine-glyoxylate aminotransferase (AGT) enzyme activity assessment. However, due to its convenience, AGXT gene sequencing has increasingly become the preferred diagnostic method. Conservative treatments for PH1 include adequate fluid intake, citrate, vitamin B6, and continuous renal replacement therapy, while liver transplantation is the only curative treatment. Infants with unexplained acute renal failure should be evaluated for PH1, with early detection of the level of urine oxalate and screening for genetic testing recommended.

Unveiling atypical diagnoses: when whole-genome analysis performed for refractory infantile hypomagnesemia reveals primary hyperoxaluria.

BACKGROUND: Genetic testing is increasingly recognized as crucial in inherited nephropathies. Here, we report on an atypical presentation of a complex tubulopathy that led to an unexpected diagnosis of primary hyperoxaluria type 1 (PH1). CASE DIAGNOSIS: At 2 weeks of age, a premature boy with stunted growth was diagnosed with complex tubulopathy associating hyponatremia, hypokalemia, hypomagnesemia, hypophosphatemia, metabolic acidosis, and acute kidney injury. Despite electrolyte replacement, severe hypomagnesemia persisted while massive parallel sequencing of genes involved in hypomagnesemia yielded negative results, including HNF1ß. At 3 years of age, despite satisfactory growth, hypomagnesemia persisted and nephrocalcinosis appeared and progressed rapidly thereafter. Whole-genome analysis then revealed compound heterozygous mutations in the AGXT gene, thus leading to the diagnosis of PH1. CONCLUSION: Given the emergence of new targeted therapies, thorough genetic analysis including whole-genome analysis should be pursued, especially in case of atypical clinical presentation.

The Evolving Role of Genetic Testing in Monogenic Kidney Stone Disease: Spotlight on Primary Hyperoxaluria.

PURPOSE: Multiple factors are thought to give rise to common, recurrent kidney stone disease, but for monogenic stone disorders a firm diagnosis is possible through genetic testing. The autosomal recessive primary hyperoxalurias (PH) are rare forms of monogenic kidney stone disease. All 3 types of PH are caused by inborn errors of glyoxylate metabolism in the liver, leading to hepatic oxalate overproduction and excessive renal urinary oxalate excretion. These conditions are characterized by kidney stones, nephrocalcinosis, progressive chronic kidney disease, and kidney failure. Systemic oxalosis, the extra-renal deposition of oxalate resulting in severe morbidity and mortality, occurs in chronic kidney disease when oxalate clearance by the kidneys declines. Novel small interfering RNA-based therapeutics targeting the liver to reduce urinary oxalate excretion have been approved, introducing precision medicine to treat primary hyperoxaluria type 1. The goal of this narrative review is to address the benefits and practicalities of genetic testing for suspected monogenic kidney stone disease and the critical roles of a multidisciplinary team. MATERIALS AND METHODS: We collated our procedures, education, training, and workflows to help other clinicians integrate genetic assessment into their diagnostic routines. RESULTS: In our experience, increased access to genetic testing facilitates early detection of PH and other monogenic causes of kidney stone disease so that individualized care can be instituted promptly. CONCLUSIONS: Alongside biochemical assessments, more widespread genetic testing may ensure more timely diagnoses so that patients with suspected monogenic kidney stone disease gain access to an expanded range of services and enrollment in clinical trials and registries.

Luminescence-based complementation assay to assess target engagement and cell permeability of glycolate oxidase (HAO1) inhibitors.

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.

Nedosiran population pharmacokinetic and pharmacodynamic modelling and simulation to guide clinical development and dose selection in patients with primary hyperoxaluria type 1.

AIM: To characterize pharmacokinetic and pharmacodynamic profiles of nedosiran in patients with primary hyperoxaluria type 1 (PH1), identify influential covariates and confirm therapeutic doses. METHODS: A population pharmacokinetic (PK)/pharmacodynamic (PD) (POP-PKPD) model was developed to characterize the concentration-time course of nedosiran and the corresponding effect on 24-h urinary oxalate (Uox). Simulations of dosing to achieve clinically meaningful reduction in Uox in children, adolescents and adults with PH1 were performed. RESULTS: Analyses included PK data from 143 healthy participants and PH1/PH2 patients, and PD data from 46 PH1 patients. Nedosiran PK was described by a two-compartment model with dual n-transit absorption and parallel linear and nonlinear elimination. The relationship between nedosiran exposure and Uox was described by an indirect response model. Body weight, estimated glomerular filtration rate (eGFR) and disease status were identified as influential covariates for the POP-PK model. The simulation results supported a weight-banded dosing regimen of nedosiran sodium in adolescents and adults (≥12 years) with PH1 of 170 mg (weight ≥50 kg) and 136 mg (weight <50 kg), in children (6-11 years) with PH1 of 3.5 mg/kg, and no dose adjustments for PH1 patients with relatively preserved kidney function (eGFR ≥ 30 mL/min/1.73m2). Following the proposed dosing regimens, the simulated median fold-changes in PK AUC0-τ,ss were acceptable (≤1.51 fold-change) and ~71% of PH1 patients across all age groups achieved near-normal Uox (<0.6 mmol) by week 52. CONCLUSIONS: The final POP-PKPD model characterizes observed nedosiran PK and Uox data. Simulations support nedosiran dosing regimens in PH1 patients aged ≥6 years with relatively preserved kidney function.

Mutation Characteristics of Primary Hyperoxaluria in the Chinese Population and Current International Diagnosis and Treatment Status.

Background: Primary hyperoxaluria (PH) is a rare autosomal recessive disorder, mainly due to the increase in endogenous oxalate production, causing a series of clinical features such as kidney stones, nephrocalcinosis, progressive impairment of renal function, and systemic oxalosis. There are three common genetic causes of glycolate metabolism anomalies. Among them, PH type 1 is the most prevalent and severe type, and early end-stage renal failure often occurs. Summary: This review summarizes PH through pathophysiology, genotype, clinical manifestation, diagnosis, and treatment options. And explore the characteristics of Chinese PH patients. Key Messages: Diagnosis of this rare disease is based on clinical symptoms, urinary or blood oxalate concentrations, liver biopsy, and genetic testing. Currently, the main treatment is massive hydration, citrate inhibition of crystallization, dialysis, liver and kidney transplantation, and pyridoxine. Recently, RNA interference drugs have also been used. In addition, technologies such as gene editing and autologous liver cell transplantation are also being developed. C.815_816insGA and c.33_34insC mutation in the AGXT gene could be a common variant in Chinese PH1 population. Mutations at the end of exon 6 account for approximately 50% of all Chinese HOGA1 mutations. Currently, the treatment of PH in China still relies mainly on symptomatic and high-throughput dialysis, with poor prognosis (especially for PH1 patients).

Efficacy and Safety of Lumasiran in Patients With Primary Hyperoxaluria Type 1: Results from a Phase III Clinical Trial.

Introduction: Patients with primary hyperoxaluria type 1 (PH1), a genetic disorder associated with hepatic oxalate overproduction, frequently experience recurrent kidney stones and worsening kidney function. Lumasiran is indicated for the treatment of PH1 to lower urinary and plasma oxalate (POx). Methods: ILLUMINATE-A (NCT03681184) is a phase III trial in patients aged ≥6 years with PH1 and estimated glomerular filtration rate (eGFR) ≥30 ml/min per 1.73 m2. A 6-month double-blind placebo-controlled period is followed by an extension period (≤54 months; all patients receive lumasiran). We report interim data through month 36. Results: Of 39 patients enrolled, 24 of 26 (lumasiran/lumasiran group) and 13 of 13 (placebo/lumasiran group) entered and continue in the extension period. At month 36, in the lumasiran/lumasiran group (36 months of lumasiran treatment) and placebo/lumasiran group (30 months of lumasiran treatment), mean 24-hour urinary oxalate (UOx) reductions from baseline were 63% and 58%, respectively; 76% and 92% of patients reached a 24-hour UOx excretion ≤1.5× the upper limit of normal (ULN). eGFR remained stable. Kidney stone event rates decreased from 2.31 (95% confidence interval: 1.88-2.84) per person-year (PY) during the 12 months before consent to 0.60 (0.46-0.77) per PY during lumasiran treatment. Medullary nephrocalcinosis generally remained stable or improved; approximately one-third of patients (both groups) improved to complete resolution. The most common lumasiran-related adverse events (AEs) were mild, transient injection-site reactions. Conclusion: In patients with PH1, longer-term lumasiran treatment led to sustained reduction in UOx excretion, with an acceptable safety profile and encouraging clinical outcomes.See for Video Abstract.

Modified by the Innovative Drugs and Strategies-Pattern of Selected Indications for Pediatric Liver Transplantation.

BACKGROUND: Liver transplantation (LTx) constitutes a major life-saving routine treatment for children with end-stage liver disease. However, the analysis of LTx registries in children provides much information about changes in the indication profiles in the recent years. METHODS: The article provides a comprehensive review about the successes, hopes, and challenges related to changing indications for LTx in children based on the literature review and our own experience. Retrospective review of the indications for LTx at a tertiary referral pediatric hospital was also presented. RESULTS AND CONCLUSIONS: In the context of the new therapies that have emerged, the need for LTx has decreased in patients with chronic hepatitis B and C infection and tyrosinemia type 1. In primary hyperoxaluria type 1, new RNAi-based therapy has eliminated the requirement for LTx (both isolated or combined). There is a hope that introduction of ileal bile acid transporter (IBAT) blockers reduces the need for LTx in patients with Alagille syndrome or progressive familial intrahepatic cholestasis. The number of children qualified for LTx with urea cycle disorders (UCDs) as a prophylaxis of neurodevelopmental impairment is increasing.

4-hydroxy-2-oxoglutarate metabolism in a mouse model of Primary Hyperoxaluria Type 3.

Primary Hyperoxaluria Type 3 (PH3) results from 4-hydroxy-2-oxoglutarate (HOG) aldolase (HOGA) deficiency, which causes an increase in endogenous oxalate synthesis leading to calcium oxalate kidney stone disease. The mechanisms underlying HOG metabolism and increased oxalate synthesis in PH3 are not well understood. We used a Hoga1 knock-out mouse model of PH3 to investigate two aspects of HOG metabolism: reduction to dihydroxyglutarate (DHG), a pathway that may limit oxalate synthesis in PH3, and metabolism to glyoxylate, which is a direct precursor to oxalate. The metabolism of HOG to DHG was highest in liver and kidney cortical tissue, enhanced in the cytosolic compartment of the liver, and preferred NADPH as a cofactor. In the absence of HOGA, HOG to glyoxylate aldolase activity was highest in liver mitoplasts, with no activity present in brain tissue lysates. These findings will assist in the identification of enzymes responsible for the metabolism of HOG to DHG and glyoxylate, which may lead to novel therapeutic approaches to limit oxalate synthesis in those afflicted with PH3.

Urinary Oxalate Excretion During Pregnancy in Primary Hyperoxaluria Type 1: A Report of 4 Cases.

Primary hyperoxaluria (PH) is a rare genetic disorder characterized by excessive oxalate production because of specific gene defects. PH1 is the most prevalent type, causing recurrent kidney stone disease and often leading to chronic kidney disease and kidney failure. Our previous study suggested that pregnancy did not adversely affect kidney function in female patients with PH. In this study, we identified 4 PH1 cases with urinary oxalate (UOx) measurements during pregnancy from the Rare Kidney Stone Consortium and Oxalosis and Hyperoxaluria Foundation PH registry to investigate UOx levels during pregnancy in patients with PH1. The PH Registry is approved by the Institutional Review Board of Mayo Clinic (Rochester, MN). All 4 showed a decrease in UOx during pregnancy when compared with before pregnancy and after delivery. These findings contrast with those of the general population, in which the UOx tends to increase during pregnancy because of a simultaneous physiological increase in the glomerular filtration rate. Elucidating the mechanism underlying reduced UOx during pregnancy in PH1 could suggest novel PH therapies. These findings could also affect the clinical management and have implications regarding the safety of withholding novel PH1-directed molecular therapies that currently have uncertain safety profiles during pregnancy. We highlight the need for additional data on urinary changes in patients with PH and other populations while pregnant to clarify changes in UOx throughout pregnancy.

Nedosiran Safety and Efficacy in PH1: Interim Analysis of PHYOX3.

Introduction: Primary hyperoxaluria (PH) is a rare genetic disorder of hepatic glyoxylate metabolism. Nedosiran is an RNA interference (RNAi) therapeutic that the US Food and Drug Administration has approved for treatment of PH1. PHYOX3 is a trial evaluating monthly nedosiran in patients with PH. Methods: In this PHYOX3 interim analysis, participants with PH1 who continued from a single-dose nedosiran trial (PHYOX1), with no previous kidney or liver transplantation, dialysis, or evidence of systemic oxalosis were eligible. The safety and efficacy of once-monthly nedosiran was assessed over 30 months. Results: Thirteen participants completed PHYOX1 and continued into PHYOX3. At baseline, the mean (SD) and median (range) age was 24.2 (6.6) years and 23.0 (14-39) years, respectively; 53.8% were female and 61.5% were White. Mean estimated glomerular filtration rate (eGFR) remained stable (62-84.2 mL/min per 1.73 m2) to month 30. Mean 24-hour urinary oxalate (Uox) excretion showed a sustained reduction from baseline of ≥60% at every visit (months 2-30). From month 2, at least 10 of 13 (76.9%) participants achieved normal (<0.46 mmol/24h; upper limit of assay-normal [ULN]) or near-normal (≥0.46 to <0.60 mmol/24h; ≥ULN to <1.3 × ULN) 24-hour Uox excretion. All participants experienced ≥1 adverse event (AE), mostly mild or moderate in severity (primarily, injection site events). Three serious, not treatment-related AEs were reported; there were no deaths or study discontinuations due to AEs. Conclusion: Nedosiran was well-tolerated in patients with PH1, and treatment resulted in a sustained, substantial reduction in Uox excretion for at least 30 months in this long-term study. No safety signals have been identified to date. The PHYOX3 study is ongoing.

Simultaneous Liver Kidney Transplantation in a Primary Type 2 Hyperoxaluria With Corrected TOF and Severe Cardiomyopathy: A Case Report.

Background: Primary type 2 hyperoxaluria is a very rare genetic disorder,1,2 where in the progression to renal failure was assumed to be insidious and not very common.3 PH2 is due to deficient glyoxylate reductase/hydroxypyruvate reductase (GRHPR),1,2 which was thought to have extra-hepatic production also.4 The progression to renal failure in these patient subgroups is well documented in the Literature and the role of SLK (simultaneous liver and kidney transplantation) has not been clearly established.8. Method: We present a case report of a young girl with PH2, who successfully underwent SLK, with evidence of reduction in the urine oxalate levels post SLK. Results: PH2, though a rare genetic disease, has a proven potential to progress to chronic renal failure requiring transplantation, renal transplantation alone has not shown any benefit, these patients can be offered SLK as a primary treatment option, to improve the outcomes, this needs further validation with consensus and studies.

Diagnosis and management of primary hyperoxalurias: best practices.

The primary hyperoxalurias (PH 1, 2, and 3) are rare autosomal recessive disorders of glyoxylate metabolism resulting in hepatic overproduction of oxalate. Clinical presentations that should prompt consideration of PH include kidney stones, nephrocalcinosis, and kidney failure of unknown etiology, especially with echogenic kidneys on ultrasound. PH1 is the most common and severe of the primary hyperoxalurias with a high incidence of kidney failure as early as infancy. Until the recent availability of a novel RNA interference (RNAi) agent, PH care was largely supportive of eventual need for kidney/liver transplantation in PH1 and PH2. Together with the Oxalosis and Hyperoxaluria Foundation, the authors developed a diagnostic algorithm for PH1 and in this report outline best clinical practices related to its early diagnosis, supportive treatment, and long-term management, including the use of the novel RNAi. PH1-focused approaches to dialysis and kidney/liver transplantation for PH patients with progression to chronic kidney disease/kidney failure and systemic oxalosis are suggested. Therapeutic advances for this devastating disease heighten the importance of early diagnosis and informed treatment.

Navigating the Evolving Landscape of Primary Hyperoxaluria: Traditional Management Defied by the Rise of Novel Molecular Drugs.

Primary hyperoxalurias (PHs) are inherited metabolic disorders marked by enzymatic cascade disruption, leading to excessive oxalate production that is subsequently excreted in the urine. Calcium oxalate deposition in the renal tubules and interstitium triggers renal injury, precipitating systemic oxalate build-up and subsequent secondary organ impairment. Recent explorations of novel therapeutic strategies have challenged and necessitated the reassessment of established management frameworks. The execution of diverse clinical trials across various medication classes has provided new insights and knowledge. With the evolution of PH treatments reaching a new milestone, prompt and accurate diagnosis is increasingly critical. Developing early, effective management and treatment plans is essential to improve the long-term quality of life for PH patients.

Lumasiran treatment in pediatric patients with PH1: real-world data within a compassionate use program in Italy.

Background: Primary hyperoxaluria (PH) is a rare, severe genetic disorder, characterized by increased urinary excretion of calcium oxalate, which is responsible for kidney damage and systemic clinical manifestations. Since the year 2020, a new molecule, lumasiran, based on RNA interference (RNAi) technology, has been added to the traditional therapeutic approach. The aim of this analysis was to define the baseline characteristics of a PH1 pediatric population treated with lumasiran in a compassionate-use program setting, and to evaluate the medium-term efficacy of this drug in the routine clinical setting. Methods: A retrospective observational analysis was conducted in nine pediatric patients (male:female 5:4; median age at lumasiran start 1.9 years, range 0-14.1). Data concerning oxalate concentration in plasma and urine, kidney stones events, ultrasound and kidney function were collected during the study period (follow-up, mean ± standard deviation: 15.3 ± 5 months). Results: In this analysis, a reduction in the urinary oxalate to creatinine ratio (reduction range within the sixth month of treatment from 25.8% to 69.6%, median 51.2%) as well as plasma oxalate concentration under the limit of supersaturation of oxalate in all the patients. Only one patient presented new stone events; kidney ultrasonographic findings related to nephrocalcinosis remained stable in eight out of nine patients. Glomerular filtration rate remained stable during treatment. No adverse events related to lumasiran were noted. Conclusion: Data from this analysis support the efficacy and safety of lumasiran in a pediatric clinical setting, especially if administrated in early life.

Primary hyperoxaluria in adults and children: a nationwide cohort highlights a persistent diagnostic delay.

Background: Primary hyperoxalurias (PH) are extremely rare genetic disorders characterized by clinical heterogeneity. Delay in diagnosing these conditions can have detrimental effects on patient outcomes. The primary objective of this study is to assess the current diagnostic delay for PH. Methods: This nationwide, observational and retrospective study included patients who received a genetic diagnosis of PH types 1, 2 and 3 between 1 January 2015 and 31 December 2019. Diagnostic delay was defined as the duration between the onset of symptoms and the time of genetic diagnosis. Results: A total of 52 patients (34 children and 18 adults) were included in the study, with 40 PH1 (77%), 3 PH2 (6%) and 9 PH3 (17%). At the time of diagnosis, 12 patients (23%) required dialysis. Among the PH1 patients, the predominant symptom at onset in adults was renal colic (79% of cases), whereas symptoms in children were more diverse (renal colic in 17% of cases). The diagnostic delay was significantly shorter in children compared with adults [median (interquartile range)]: 1.2 (0.1-3.0) versus 30 (17-36) years, respectively (P < .0001). RNA interference was utilized in 23 patients (58%). Five individuals (13%) underwent double liver-kidney transplantation, and five (13%) received isolated kidney transplantation, with lumasiran therapy in four patients. For PH2 and PH3 patients, the diagnostic delay ranges from 0 to 3 years, with renal colic as first symptom in 33% of cases. Conclusion: This extensive and recent cohort of PH underscores the considerable delay in diagnosing PH, particularly in adults, even in a country with a dedicated organization for enhancing the overall management of rare diseases. These findings reinforce the imperative for increased awareness among relevant specialties regarding the evaluation of urolithiasis.

Clinical features and mutational spectrum of Chinese patients with primary hyperoxaluria type 2.

Primary hyperoxaluria type 2 (PH2) is a rare hereditary disease that causes nephrolithiasis, nephrocalcinosis and kidney failure. This study aimed to investigate the clinical features and mutational spectrum of Chinese patients with PH2. A retrospective cohort study was performed on PH2 patients admitted to our center over seven years. We also systematically reviewed all the articles on Chinese PH2 patients published from January 2000 to May 2023 and conducted a meta-analysis. A total of 25 PH2 patients (10 from our center and 15 from published studies) were included in this study. The median age of onset in patients from our center was 8.50 (1.00, 24.00) years, and 50% were male. Among the full cohort of 25 Chinese patients, the median age of onset was 8.00 (0.40, 26.00) years, and 64% of them were male. Seven patients progressed to end-stage kidney disease, with a median age of 27.50 (12, 31) years. The cumulative renal survival rates were 100%, 91.67%, 45.83% and 30.56% at 10, 20, 30 and 40 years of age, respectively. A total of 18 different variants were identified, and c.864_865del was the dominant variant, accounting for 57.69% of the total alleles. Patients who were heterozygous for c.864_865del were more susceptible to nephrocalcinosis than those who were homozygous for c.864_865del and those harboring other mutations (83.33% versus 33.3% and 0%, respectively) (p = 0.025). The clinical features and mutational spectrum of Chinese PH2 patients were described. This study helps to expand awareness of the phenotypes and genotypes of Chinese PH2 patients and contributes to the improvement of diagnostic and treatment strategies for PH2 patients.

Expanding the Genetic Spectrum of AGXT Gene Variants in Egyptian Patients with Primary Hyperoxaluria Type I.

Introduction: Approximately 80% of primary hyperoxaluria cases are caused by primary hyperoxaluria type 1 (PH1, OMIM# 259900), which is characterized by pathogenic variants in the AGXT gene, resulting in deficiency of the liver-specific enzyme alanine-glyoxylate aminotransferase (AGT). This leads to increased production of oxalate, which cannot be effectively eliminated from the body, resulting in its accumulation primarily in the kidneys and other organs. Subjects and Methods: This study included 17 PH1 Egyptian patients from 12 unrelated families, recruited from the Inherited Kidney Disease Outpatient Clinic and the Dialysis Units, Cairo University Hospitals, during the period from January 2018 to December 2019, aiming to identify the pathogenic variants in the AGXT gene. Results: Six different variants were detected. These included three frameshift and three missense variants, all found in homozygosity within the respective families. The most common variant was c.121G>A;p.(Gly41Arg) detected in four families, followed by c.725dup;p.(Asp243GlyfsTer12) in three families, c.33dup;p.(Lys12Glnfs156) in two families, and c.731T >C;p.(Ile244Thr), c.33delC;p.(Lys12Argfs34), and c.568G>A;p.(Gly190Arg) detected in one family each. Conclusion: Consanguineous Egyptian families with history of renal stones or renal disease suspicious of primary hyperoxaluria should undergo AGXT genetic sequencing, specifically targeting exons 1 and 7, as variants in these two exons account for >75% of disease-causing variants in Egyptian patients with confirmed PH1.