RARE DISEASE
Cystinuria type A
Cystinuria type A
Cystinuria type A
Drug discovery
161
papers
On emerging therapies
Overview
Cystinuria Type A is an autosomal recessive disorder caused by SLC3A1 mutations, leading to defective renal reabsorption of cystine and dibasic amino acids. This results in recurrent cystine nephrolithiasis, often manifesting in the first two decades of life. Bilateral or large stones (>12 mm) are common, with a high recurrence rate despite treatment. Diagnosis involves urinary cystine quantification, imaging, and genetic testing [1][2][4][10].
Therapies
Hydration: >3 L/day urine output to reduce cystine concentration [3][8][12].
Alkalinization: Potassium citrate (target urine pH 7–7.5) to enhance cystine solubility [3][15][16].
Thiol drugs: Tiopronin (α-MPG) or D-penicillamine for refractory cases; surgical interventions (e.g., laser lithotripsy) for stones >12 mm [1][3][12].
Categories: rare genetic diseases, rare inborn errors of metabolism, rare renal diseases, rare transplant-related disorders
Research Papers
161 drug discovery papers about Cystinuria type A, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
161 drug discovery papers about Cystinuria type A, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
small molecules
2026-08-02 | Cystinuria: Diagnosis, Medical and Surgical Management, and Emerging Therapies. A Narrative Review.
Cystinuria is a hereditary aminoaciduria causing recurrent cystine nephrolithiasis, impaired quality of life and potential renal function decline. Despite established treatment guidelines, real-world data reveal a persistent gap between recommended targets and clinical outcomes. Preliminary data from the EUROCYS 2024 prospective European registry (269 patients, 29 centers, 8 countries) showed that only 16.3% of patients achieved the target urinary pH range, 55.2% remained above the conventional urinary cystine threshold of 250 mg/L, and approximately 39% experienced a new stone event within the preceding 12 months, despite follow-up in specialist centers. Discontinuation rates for available thiol drugs have been reported to reach 30-50%. This narrative review, based on a structured non-systematic search of major databases and guideline repositories (2009-2026), synthesizes current evidence on cystinuria diagnosis and management and appraises emerging adjunctive interventions. Next-generation sequencing-based genetic testing and the cystine capacity assay represent key recent advances in monitoring. Thulium fiber laser lithotripsy and miniaturized percutaneous approaches offer less traumatic surgical options in this high-burden population. Oral N-acetylcysteine has mechanistic plausibility and a favorable, well-characterized safety profile in other clinical settings, making it a rational candidate for formal prospective evaluation; however, robust clinical trial evidence in cystinuria using contemporary monitoring parameters is lacking. Current standard treatment remains insufficient for a substantial proportion of patients, underscoring the need to evaluate accessible adjunctive therapies with defined mechanisms and measurable outcomes.
2026-03-11 | L -Ergothioneine Attenuates Nephrolithiasis by Modulating Redox Signaling and Mitochondrial Function in Cystine and Calcium Oxalate Models
AIMS: Nephrolithiasis is a major global health challenge, with oxidative stress and mitochondrial dysfunction emerging as key drivers of renal injury and stone formation. l-ergothioneine (l-Erg), a naturally occurring antioxidant transported by OCTN1, has shown promising effects in cystinuria models, preventing stone formation. Despite evidence supporting an indirect mechanism of action, key mechanistic aspects have yet to be fully clarified. This study aimed to evaluate whether l-Erg can prevent stone progression in cystinuria and in other types of lithiasis, such as calcium oxalate nephrolithiasis, and to further elucidate its mechanistic basis. RESULTS: Using mouse models, l-Erg significantly reduced cystine stone growth and renal inflammation, and its combination with d-penicillamine enhanced stone dissolution and mitigated drug-related toxicity. In calcium oxalate nephrolithiasis, l-Erg decreased crystal deposition, preserved renal architecture, normalized glutathione levels, and restored mitochondrial respiration. Transcriptomic analysis revealed downregulation of immune pathways and activation of cell cycle genes, suggesting attenuation of inflammation and promotion of tubular repair. INNOVATION: This study is the first to demonstrate that l-Erg exerts renoprotective effects through combined antioxidant and mitochondrial mechanisms in two major forms of nephrolithiasis and introduces a dual therapeutic approach combining an antioxidant with a cystine-solubilizing agent. CONCLUSION: 44, 878-891.
2025-09-25 | Urinary Cystine/Creatinine Concentrations Before and After Castration in Dogs With Suspected Androgen-Dependent Cystine Urolithiasis.
Androgen-dependent cystinuria has been described in intact male dogs. Castration has been recommended to reduce urinary cystine excretion. Urinary cystine/creatinine concentration will significantly decrease in dogs with suspected androgen-dependent (Type III) cystinuria after castration and will be associated with a lack of sonographic evidence of urolithiasis. Six intact male dogs with cystine uroliths. Prospective, observational study. Urinary amino acid/creatinine concentrations and abdominal ultrasound were evaluated at baseline (T0), 30 days (T30), and 90 days (T90) after castration and urolith removal. No dietary change was recommended unless urolith recurrence was noted. DNA was evaluated for the cystinuria-associated marker for Type III cystinuria. The median decline in urinary cystine/creatinine (uCys/creat) concentration from T0 to T30 was 577 nmol/mg (IQR, 415-969; p = 0.03), from T0 to T90 was 798 nmol/mg (IQR, 580-989; p = 0.03) and from T30 to T90 was 34 nmol/mg (IQR, 19.5-443; p = 0.03). Two dogs had small (2.5-3 mm) uroliths at T30, which resolved in one of them at T90. Both dogs with ultrasonographic evidence of recurrence at T30 were positive for the cystinuria-associated genetic marker, although no signs of lower urinary tract disease were noted in either dog. Three of 6 enrolled dogs were homozygous positive for the genetic marker. Castration should be considered for intact male dogs with cystine urolithiasis.
2024-02-22 | Effect of urine alkalization on urinary inflammatory markers in cystinuric patients
ABSTRACT Background Cystinuria is associated with a high prevalence of chronic kidney disease (CKD). We previously described a urinary inflammatory-protein signature (UIS), including 38 upregulated proteins, in cystinuric patients (Cys-patients), compared with healthy controls (HC). This UIS was higher in Cys-patients with CKD. In the present observational study, we aimed to investigate the UIS in Cys-patients without CKD and patients with calcium nephrolithiasis (Lith-patients), versus HC and the effect of urine alkalization on the UIS of Cys-patients. Methods UIS was evaluated by nano-liquid chromatography coupled to high-resolution mass spectrometry in adult HC, Lith-patients and non-treated Cys-patients with an estimated glomerular filtration rate >60 mL/min/1.73 m2, and after a 3-month conventional alkalizing treatment in Cys-patients. Results Twenty-one Cys-patients [12 men, median age (interquartile range) 30.0 (25.0–44.0) years], 12 Lith-patients [8 men, 46.2 (39.5–54.2) years] and 7 HC [2 men, 43.1 (31.0–53.9) years] were included. Among the 38 proteins upregulated in our previous work, 11 proteins were also upregulated in Cys-patients compared with HC in this study (5 circulating inflammatory proteins and 6 neutrophil-derived proteins). This UIS was also found in some Lith-patients. Using this UIS, we identified two subclusters of Cys-patients (5 with a very high/high UIS and 16 with a moderate/low UIS). In the Cys-patients with very high/high UIS, urine alkalization induced a significant decrease in urinary neutrophil-derived proteins. Conclusion A high UIS is present in some Cys-patients without CKD and decreases under alkalizing treatment. This UIS could be a prognostic marker to predict the evolution towards CKD in cystinuria.
2023-12-11 | Acetazolamide and human carbonic anhydrases: retrospect, review and discussion of an intimate relationship
Acetazolamide (AZM) is a strong pharmacological sulphonamide-type (R-SO2-NH2, pKa 7.2) inhibitor of the activity of several carbonic anhydrase (CA) isoforms, notably of renal CA II (Ki, 12 nM) and CA IV (Ki, 74 nM). AZM is clinically used for about eighty years in various diseases including epilepsy and glaucoma. Pharmacological AZM increases temporarily the urinary excretion of bicarbonate (HCO3–) and sodium ions (Na+) and sustainably the urinary pH. AZM is excreted almost unchanged over several hours at high rates in the urine. Closely parallel concentrations of circulating and excretory AZM are observed upon administration of therapeutical doses of AZM. In a proof-of-principle study, we investigated the effects of the ingestion of a 250-mg AZM-containing tablet by a healthy volunteer on the urinary excretion of organic and inorganic substances over 5 h (range, 0, 0.5, 1, 1.5, 2, 3, 4, 5 h). Measured analytes included: AZM, amino acids and their metabolites such as guanidinoacetate, i.e. the precursor of creatine, of asymmetrically (ADMA) and symmetrically (SDMA) dimethylated arginine, nitrite (O = N-O–, pKa 3.4) and nitrate (O2N-O–, pKa −1.37), the major metabolites of nitric oxide (NO), the C-H acidic malondialdehyde (MDA; (CHO)2CH2, pKa 4.5), and creatinine for correction of analytes excretion. All analytes were measured by validated isotopologues using gas chromatography-mass spectrometry (GC-MS) methods. AZM excretion in the urine reached its maximum value after 2 h and was fairly stable for the next 3 h. Time series analysis by the ARIMA method was performed. AZM ingestion increased temporarily the urinary excretion of the amino acids Leu + Ile, nitrite and nitrate, decreased temporarily the urinary excretion of other amino acids. AZM decreased sustainably the urinary excretion of MDA, a biomarker of oxidative stress (i.e. lipid peroxidation). Whether this decrease is due to inhibition of the excretion of MDA or attenuation of oxidative stress by AZM is unknown. The acute and chronic effects of AZM on the urinary excretion of electrolytes and physiological substances reported in the literature are discussed in depth in the light of its extraordinary pharmacokinetics and pharmacodynamics. Tolerance development/drug resistance to AZM in chronic use and potential mechanisms are also addressed.
gene therapies
2025-08-12 | Partial correction of cystinuria type A in mice via kidney-targeted transposon delivery.
We used kidney-targeted, non-viral, transposon-mediated gene delivery to express the mouse Slc3a1 transgene in one kidney of cystinuria type A (Slc3a1 -/-) mice. We found a 44% reduction in urinary cystine concentration at 154 days post-gene transfer, although there was no significant effect on cystine stone formation. Our results indicate that it is possible to achieve kidney-targeted gene transfer, resulting in reduction of cystine concentration in the urine of a cystinuria type A animal model. This proof of concept lays the foundation for future studies directed at gene therapy for cystinuria and other kidney diseases.
2024-05-20 | Genome editing and kidney health.
Genome editing technologies, clustered regularly interspaced short palindromic repeats (CRISPR)-Cas in particular, have revolutionized the field of genetic engineering, providing promising avenues for treating various genetic diseases. Chronic kidney disease (CKD), a significant health concern affecting millions of individuals worldwide, can arise from either monogenic or polygenic mutations. With recent advancements in genomic sequencing, valuable insights into disease-causing mutations can be obtained, allowing for the development of new treatments for these genetic disorders. CRISPR-based treatments have emerged as potential therapies, especially for monogenic diseases, offering the ability to correct mutations and eliminate disease phenotypes. Innovations in genome editing have led to enhanced efficiency, specificity and ease of use, surpassing earlier editing tools such as zinc-finger nucleases and transcription activator-like effector nucleases (TALENs). Two prominent advancements in CRISPR-based gene editing are prime editing and base editing. Prime editing allows precise and efficient genome modifications without inducing double-stranded DNA breaks (DSBs), while base editing enables targeted changes to individual nucleotides in both RNA and DNA, promising disease correction in the absence of DSBs. These technologies have the potential to treat genetic kidney diseases through specific correction of disease-causing mutations, such as somatic mutations in PKD1 and PKD2 for polycystic kidney disease; NPHS1, NPHS2 and TRPC6 for focal segmental glomerulosclerosis; COL4A3, COL4A4 and COL4A5 for Alport syndrome; SLC3A1 and SLC7A9 for cystinuria and even VHL for renal cell carcinoma. Apart from editing the DNA sequence, CRISPR-mediated epigenome editing offers a cost-effective method for targeted treatment providing new avenues for therapeutic development, given that epigenetic modifications are associated with the development of various kidney disorders. However, there are challenges to overcome, including developing efficient delivery methods, improving safety and reducing off-target effects. Efforts to improve CRISPR-Cas technologies involve optimizing delivery vectors, employing viral and non-viral approaches and minimizing immunogenicity. With research in animal models providing promising results in rescuing the expression of wild-type podocin in mouse models of nephrotic syndrome and successful clinical trials in the early stages of various disorders, including cancer immunotherapy, there is hope for successful translation of genome editing to kidney diseases.
2021-02-02 | CRISPR/Cas9 engineering of albino cystinuria Type A mice.
Cystinuria Type A is a relatively common genetic kidney disease occurring in 1 in 7,000 people worldwide that results from mutation of the cystine transporter rBAT encoded by Slc3a1. We used CRISPR/Cas9 technology to engineer cystinuria Type A mice via genome editing of the C57BL/6NHsd background. These mice are an improvement on currently available models as they are on a coisogenic genetic background and have a single defined mutation. In order to use albinism to track Cas9 activity, we co-injected gRNAs targeting Slc3a1 and tyrosinase (Tyr) with Cas9 expressing plasmid DNA into mouse embryos. Two different Slc3a1 mutational alleles were derived, with homozygous mice of both demonstrating elevated urinary cystine levels, cystine crystals, and bladder stones. We used whole genome sequencing to evaluate for potential off-target editing. No off-target indels were observed for the top 10 predicted off-targets for Slc3a1 or Tyr. Therefore, we used CRISPR/Cas9 to generate coisogenic albino cystinuria Type A mice that could be used for in vivo imaging, further study, or developing new treatments of cystinuria.
2006-01-01 | 221. A New Retroviral Gene Therapy Approach for Cystinuria Research
Objectives: For cystinuria, gene therapy might provide a correction of the cellular dysfunction by expressing the deficient gene. Currently there is no stable cellular model which mimics the cystinuria phenotype and genotype to study the potential benefits of gene therapy in vitro. We initially developed an antisense expressing vector for the SLC3A1 gene using a non viral vector. To optimize the system we decided to create stable cell lines with retroviral vectors. Retroviral vectors are efficient vehicles to deliver genes into the cell and for stable integration into the genome. We used Murine leukemia virus (MLV) vector to generate a stable cell line which represents the cystinuria type 1 disease in vitro to serve as a tool for the development of gene therapy. Materials and methods: HK-2 is a proximal tubular cell (PTC) line derived from normal human kidney. The presence of the SLC3A1 (rBAT) gene was determined using the c-DNA of HK-2 cells by PCR with the SLC3A1 primers. The SLC3A1 gene was cloned into a Murine leukemia virus (MLV) transfer vector. This vector additionally contains a puromycin resistance marker. We also cloned the SLC3A1 gene in an antisense orientation to obtain a knockout of the rBAT protein by antisense RNA. Two controls were generated with mutations in the start codons of the both the sense and antisense constructs. Phoenix A is a second-generation MLV packaging cell line for the generation of helper free amphotropic retroviral vectors. Calcium phosphate was used to transfect the individual vector into the phoenix cells to generate the virus with the respective SLC3A1 constructs. The viral particles are obtained from the supernatant and filtered through a 0,45 μM filter to obtain cell-free supernatant. The four different viral supernatants are then used to transduce the target HK-2 cells in the presence of polybrene. 48 hrs post infection the HK-2 cells were subjected to puromycin selection (1 microgram/ml). After 3 days the selection pressure was removed and the cells were cultured normally. Results: The SLC3A1 gene amplified by RT-PCR from HK-2 cells in sense and anti sense orientation was analyzed by automated sequencing. The HK-2 cells after transduction with the different viral vectors and after puromycin selection were checked by PCR and Western blot for the expression of the constructs. Discussion: The stable knock down cell line representing the cystinuria type 1 can be used to validate the efficiency of gene therapy in vitro. We would transduce the stable knock down cell line of the SLC3A1 gene with a feline immunodeficiency viral (FIV) vector expressing the SLC3A1 gene to determine the efficiency of gene therapy and to compare it to the FIV based gene therapy of the cystinuria animal model in vivo.
oligonucleotides
2025-09-03 | Clinical and genotypic features, renal prognosis of orphan tubulopathies with nephrocalcinosis and cystin stones in children
THE AIM : To evaluate clinical and genotypic features, renal prognosis in orphan tubulopathies with nephrocalcinosis and cys- tine calculi in 22 pediatric patients. PATIENTS AND METHODS : The study included 22 patients (from 1 year 4 months to 17 years 11 months) with orphan tubulopathies with nephrocalcinosis (22) and cystinuria, cystine stones (2). Of the 22 probands, there were 14 (63.6 %) boys and 8 (36.4 %) girls. Clinical, biochemical, imaging, and molecular genetic diagnostic methods were used. The severity of chronic kidney disease was stratified according to the K/DOQI classification (2002). RESULTS : A genetic study of 22 children with nephrocalcinosis revealed primary hyperoxaluria of types I, II, III (AGXT, GRHPR, HOGA1) in 5; familial hypomagnesemia with hypercalciuria and nephrocalcinosis (CLDN16) in 5; hypophosphatemic rickets with hypercal- ciuria and nephrocalcinosis (SLC34A3) in 3; Bartter type I syndrome (SLC12A1) in 1 and Bartter syndrome type IV (BSND) in 1, Dent1 disease (CLCN5) in 1, Dent disease 2 (OCRL) in 1, idiopathic infantile hypercalcemia type I (SLC34A1) in 1 and type II (CYP24A1) in 2. Based on the detection of mutations in the SLC3A1 and SLC7A9 genes, 2 probands were diagnosed with type I and non type I cystinuria. The features of gene mutation variants in 22 children with orphan tubulopathies with nephrocalci- nosis and cystinuria, and cystine nodules were identified. A study of kidney function in 22 children over the age of 2 years with nephrocalcinosis and cystinuria revealed CKD C1 with normal glomerular filtration rate (17), CKD C2, C3, C4 (5). A girl with familial hypomagnesemia with hypercalciuria and nephrocalcinosis due to a mutation of the CLDN16 gene, progression CKD of С1 to C4, underwent kidney transplantation at the age of 18 before starting dialysis. CONCLUSION : Features of the clinical phenotype and variants of mutations of genes of orphan tubulopathies with nephrocalcinosis and cystinuria, cystine stones in 22 children were established. Progression of CKD from C1 with normal glomerular filtration rate to C2, C3, C4 was ascertained from 22 in 5 children (25) % with primary hyperoxaluria type1 (1), hypomagnesemia with calciuria and nephrocalcinosis (3), Dent-2 Disease (1). Identification of gene mutations in molecular genetic studies in children with nephrocalcinosis and cys- tinuria establishes a clinical and genetic diagnosis, the pathogenesis of an orphan tubulopathy, and determines personalized management based on individual genetic characteristics.
2015-09-19 | Cystinuria in a patient with 19q12q13.1 deletion
Cystinuria is a genetic cause of kidney stones with a prevalence of 1 in 7000 births. So far, two genes have been described responsible for this disorder (SLC3A1 and SLC7A9). We report a patient with an SLC7A9 gene mutation located in 19q13.1 on one allele and with a 19q12q13 region deletion on the other allele. The characteristic clinical features of the 19q13.1 microdeletion syndrome include facial dysmorphism, signs of ectodermal dysplasia, growth retardation, neurologic features and genitourinary anomalies. Cystinuria has not yet been described as part of this syndrome, although one of its responsible genes (SLC7A9) is in the same genomic location. The index case is a 6-year-old male presented with distinctive facial features, cutis aplasia of the scalp, rudimentary teeth, microcephaly, intrauterine and postnatal growth retardation, psychomotor developmental delay, speech delay, epilepsy, inguinal hernias and cystinuria. An array-CGH analysis was performed, finding a large deletion of the 19q12q13.11 cytobands, which affects 19 genes. Two of them are involved in the 19q13.11 deletion syndrome and another affected gene is SLC7A9, responsible for type B cystinuria. Sanger sequencing was performed as well, detecting a heterozygous mutation of the SLC7A9 gene, located in 19q13.1. As far as we know, this is the first described case of cystinuria in a patient with SLC7A9 gene mutation located in 19q13.1 on one allele and with 19q12q13 region deletion on the other allele. Although this patient can be classified as a type B heterozygote and, therefore, his renal prognosis is not severe, the occasional nephrolithiasis found in such patients justifies a close follow-up with regular testing of urinary cystine excretion. We suggest that the recessive behavior of this case, explains the clinical features regarding cystinuria. We propose that in the face of patients affected of a phenotype matchable with 19q13.11 syndrome and cystinuria, a mutational or sequencing study of the SLC7A9 gene should be performed to allow an early onset of diagnosis and treatment.
2008-07-01 | Evaluation of cystine transport in cultured human kidney cells and establishment of cystinuria type I phenotype by antisense technology.
Cystinuria is a rare hereditary disease resulting in recurrent stone formation and the need for repeated invasive interventions. So far, two responsible genes have been identified which encode the two transporters, rBAT and b(0,+)AT forming a heterodimer to transport cystine in proximal tubular cells (PTC) and whose defect results in increased excretion of cystine. A human cell line mimicing the phenotype of cystinuria in vitro is yet to be developed. Human kidney (HK)-2 is a PTC line derived from normal HK. After determining the presence of rBAT gene by RT-PCR and Western blot analysis, radioactively labeled cystine (S(35)) was used to evaluate the functional presence of the amino acid transport in HK-2 cells when cultured in vitro. To achieve a cystinuria type I phenotype in HK-2 cells, the rBAT gene was silenced using antisense oligonucleotides complimentary to human rBAT mRNA. The reduced transport activity of cystine was then determined by radiolabeled cystine uptake measurements. RT-PCR and Western blot confirmed the expression of the rBAT gene in HK-2 cells. Considerable transport of the radio labeled cystine was observed in HK-2 cells and was linearly dependent on the incubation time with the amino acid. The cystine transport in rBAT knockdown cells after incubation with antisense oligonucleotides was significantly lower compared to control (0.76 vs. 0.98%; P=0.0008), proving a transient knock-down of the rBAT gene. This study demonstrates the presence of the b(0,+) amino acid transport system in human proximal tubular HK-2 cells when cultured in vitro. Inhibition of this transport system is possible by using antisense technology. A permanent inhibition of the cystine transport, based on our model, would be useful for the development and evaluation gene therapeutic approaches.
small molecules
2026-08-02 | Cystinuria: Diagnosis, Medical and Surgical Management, and Emerging Therapies. A Narrative Review.
Cystinuria is a hereditary aminoaciduria causing recurrent cystine nephrolithiasis, impaired quality of life and potential renal function decline. Despite established treatment guidelines, real-world data reveal a persistent gap between recommended targets and clinical outcomes. Preliminary data from the EUROCYS 2024 prospective European registry (269 patients, 29 centers, 8 countries) showed that only 16.3% of patients achieved the target urinary pH range, 55.2% remained above the conventional urinary cystine threshold of 250 mg/L, and approximately 39% experienced a new stone event within the preceding 12 months, despite follow-up in specialist centers. Discontinuation rates for available thiol drugs have been reported to reach 30-50%. This narrative review, based on a structured non-systematic search of major databases and guideline repositories (2009-2026), synthesizes current evidence on cystinuria diagnosis and management and appraises emerging adjunctive interventions. Next-generation sequencing-based genetic testing and the cystine capacity assay represent key recent advances in monitoring. Thulium fiber laser lithotripsy and miniaturized percutaneous approaches offer less traumatic surgical options in this high-burden population. Oral N-acetylcysteine has mechanistic plausibility and a favorable, well-characterized safety profile in other clinical settings, making it a rational candidate for formal prospective evaluation; however, robust clinical trial evidence in cystinuria using contemporary monitoring parameters is lacking. Current standard treatment remains insufficient for a substantial proportion of patients, underscoring the need to evaluate accessible adjunctive therapies with defined mechanisms and measurable outcomes.
2026-03-11 | L -Ergothioneine Attenuates Nephrolithiasis by Modulating Redox Signaling and Mitochondrial Function in Cystine and Calcium Oxalate Models
AIMS: Nephrolithiasis is a major global health challenge, with oxidative stress and mitochondrial dysfunction emerging as key drivers of renal injury and stone formation. l-ergothioneine (l-Erg), a naturally occurring antioxidant transported by OCTN1, has shown promising effects in cystinuria models, preventing stone formation. Despite evidence supporting an indirect mechanism of action, key mechanistic aspects have yet to be fully clarified. This study aimed to evaluate whether l-Erg can prevent stone progression in cystinuria and in other types of lithiasis, such as calcium oxalate nephrolithiasis, and to further elucidate its mechanistic basis. RESULTS: Using mouse models, l-Erg significantly reduced cystine stone growth and renal inflammation, and its combination with d-penicillamine enhanced stone dissolution and mitigated drug-related toxicity. In calcium oxalate nephrolithiasis, l-Erg decreased crystal deposition, preserved renal architecture, normalized glutathione levels, and restored mitochondrial respiration. Transcriptomic analysis revealed downregulation of immune pathways and activation of cell cycle genes, suggesting attenuation of inflammation and promotion of tubular repair. INNOVATION: This study is the first to demonstrate that l-Erg exerts renoprotective effects through combined antioxidant and mitochondrial mechanisms in two major forms of nephrolithiasis and introduces a dual therapeutic approach combining an antioxidant with a cystine-solubilizing agent. CONCLUSION: 44, 878-891.
2025-09-25 | Urinary Cystine/Creatinine Concentrations Before and After Castration in Dogs With Suspected Androgen-Dependent Cystine Urolithiasis.
Androgen-dependent cystinuria has been described in intact male dogs. Castration has been recommended to reduce urinary cystine excretion. Urinary cystine/creatinine concentration will significantly decrease in dogs with suspected androgen-dependent (Type III) cystinuria after castration and will be associated with a lack of sonographic evidence of urolithiasis. Six intact male dogs with cystine uroliths. Prospective, observational study. Urinary amino acid/creatinine concentrations and abdominal ultrasound were evaluated at baseline (T0), 30 days (T30), and 90 days (T90) after castration and urolith removal. No dietary change was recommended unless urolith recurrence was noted. DNA was evaluated for the cystinuria-associated marker for Type III cystinuria. The median decline in urinary cystine/creatinine (uCys/creat) concentration from T0 to T30 was 577 nmol/mg (IQR, 415-969; p = 0.03), from T0 to T90 was 798 nmol/mg (IQR, 580-989; p = 0.03) and from T30 to T90 was 34 nmol/mg (IQR, 19.5-443; p = 0.03). Two dogs had small (2.5-3 mm) uroliths at T30, which resolved in one of them at T90. Both dogs with ultrasonographic evidence of recurrence at T30 were positive for the cystinuria-associated genetic marker, although no signs of lower urinary tract disease were noted in either dog. Three of 6 enrolled dogs were homozygous positive for the genetic marker. Castration should be considered for intact male dogs with cystine urolithiasis.
2024-02-22 | Effect of urine alkalization on urinary inflammatory markers in cystinuric patients
ABSTRACT Background Cystinuria is associated with a high prevalence of chronic kidney disease (CKD). We previously described a urinary inflammatory-protein signature (UIS), including 38 upregulated proteins, in cystinuric patients (Cys-patients), compared with healthy controls (HC). This UIS was higher in Cys-patients with CKD. In the present observational study, we aimed to investigate the UIS in Cys-patients without CKD and patients with calcium nephrolithiasis (Lith-patients), versus HC and the effect of urine alkalization on the UIS of Cys-patients. Methods UIS was evaluated by nano-liquid chromatography coupled to high-resolution mass spectrometry in adult HC, Lith-patients and non-treated Cys-patients with an estimated glomerular filtration rate >60 mL/min/1.73 m2, and after a 3-month conventional alkalizing treatment in Cys-patients. Results Twenty-one Cys-patients [12 men, median age (interquartile range) 30.0 (25.0–44.0) years], 12 Lith-patients [8 men, 46.2 (39.5–54.2) years] and 7 HC [2 men, 43.1 (31.0–53.9) years] were included. Among the 38 proteins upregulated in our previous work, 11 proteins were also upregulated in Cys-patients compared with HC in this study (5 circulating inflammatory proteins and 6 neutrophil-derived proteins). This UIS was also found in some Lith-patients. Using this UIS, we identified two subclusters of Cys-patients (5 with a very high/high UIS and 16 with a moderate/low UIS). In the Cys-patients with very high/high UIS, urine alkalization induced a significant decrease in urinary neutrophil-derived proteins. Conclusion A high UIS is present in some Cys-patients without CKD and decreases under alkalizing treatment. This UIS could be a prognostic marker to predict the evolution towards CKD in cystinuria.
2023-12-11 | Acetazolamide and human carbonic anhydrases: retrospect, review and discussion of an intimate relationship
Acetazolamide (AZM) is a strong pharmacological sulphonamide-type (R-SO2-NH2, pKa 7.2) inhibitor of the activity of several carbonic anhydrase (CA) isoforms, notably of renal CA II (Ki, 12 nM) and CA IV (Ki, 74 nM). AZM is clinically used for about eighty years in various diseases including epilepsy and glaucoma. Pharmacological AZM increases temporarily the urinary excretion of bicarbonate (HCO3–) and sodium ions (Na+) and sustainably the urinary pH. AZM is excreted almost unchanged over several hours at high rates in the urine. Closely parallel concentrations of circulating and excretory AZM are observed upon administration of therapeutical doses of AZM. In a proof-of-principle study, we investigated the effects of the ingestion of a 250-mg AZM-containing tablet by a healthy volunteer on the urinary excretion of organic and inorganic substances over 5 h (range, 0, 0.5, 1, 1.5, 2, 3, 4, 5 h). Measured analytes included: AZM, amino acids and their metabolites such as guanidinoacetate, i.e. the precursor of creatine, of asymmetrically (ADMA) and symmetrically (SDMA) dimethylated arginine, nitrite (O = N-O–, pKa 3.4) and nitrate (O2N-O–, pKa −1.37), the major metabolites of nitric oxide (NO), the C-H acidic malondialdehyde (MDA; (CHO)2CH2, pKa 4.5), and creatinine for correction of analytes excretion. All analytes were measured by validated isotopologues using gas chromatography-mass spectrometry (GC-MS) methods. AZM excretion in the urine reached its maximum value after 2 h and was fairly stable for the next 3 h. Time series analysis by the ARIMA method was performed. AZM ingestion increased temporarily the urinary excretion of the amino acids Leu + Ile, nitrite and nitrate, decreased temporarily the urinary excretion of other amino acids. AZM decreased sustainably the urinary excretion of MDA, a biomarker of oxidative stress (i.e. lipid peroxidation). Whether this decrease is due to inhibition of the excretion of MDA or attenuation of oxidative stress by AZM is unknown. The acute and chronic effects of AZM on the urinary excretion of electrolytes and physiological substances reported in the literature are discussed in depth in the light of its extraordinary pharmacokinetics and pharmacodynamics. Tolerance development/drug resistance to AZM in chronic use and potential mechanisms are also addressed.
gene therapies
2025-08-12 | Partial correction of cystinuria type A in mice via kidney-targeted transposon delivery.
We used kidney-targeted, non-viral, transposon-mediated gene delivery to express the mouse Slc3a1 transgene in one kidney of cystinuria type A (Slc3a1 -/-) mice. We found a 44% reduction in urinary cystine concentration at 154 days post-gene transfer, although there was no significant effect on cystine stone formation. Our results indicate that it is possible to achieve kidney-targeted gene transfer, resulting in reduction of cystine concentration in the urine of a cystinuria type A animal model. This proof of concept lays the foundation for future studies directed at gene therapy for cystinuria and other kidney diseases.
2024-05-20 | Genome editing and kidney health.
Genome editing technologies, clustered regularly interspaced short palindromic repeats (CRISPR)-Cas in particular, have revolutionized the field of genetic engineering, providing promising avenues for treating various genetic diseases. Chronic kidney disease (CKD), a significant health concern affecting millions of individuals worldwide, can arise from either monogenic or polygenic mutations. With recent advancements in genomic sequencing, valuable insights into disease-causing mutations can be obtained, allowing for the development of new treatments for these genetic disorders. CRISPR-based treatments have emerged as potential therapies, especially for monogenic diseases, offering the ability to correct mutations and eliminate disease phenotypes. Innovations in genome editing have led to enhanced efficiency, specificity and ease of use, surpassing earlier editing tools such as zinc-finger nucleases and transcription activator-like effector nucleases (TALENs). Two prominent advancements in CRISPR-based gene editing are prime editing and base editing. Prime editing allows precise and efficient genome modifications without inducing double-stranded DNA breaks (DSBs), while base editing enables targeted changes to individual nucleotides in both RNA and DNA, promising disease correction in the absence of DSBs. These technologies have the potential to treat genetic kidney diseases through specific correction of disease-causing mutations, such as somatic mutations in PKD1 and PKD2 for polycystic kidney disease; NPHS1, NPHS2 and TRPC6 for focal segmental glomerulosclerosis; COL4A3, COL4A4 and COL4A5 for Alport syndrome; SLC3A1 and SLC7A9 for cystinuria and even VHL for renal cell carcinoma. Apart from editing the DNA sequence, CRISPR-mediated epigenome editing offers a cost-effective method for targeted treatment providing new avenues for therapeutic development, given that epigenetic modifications are associated with the development of various kidney disorders. However, there are challenges to overcome, including developing efficient delivery methods, improving safety and reducing off-target effects. Efforts to improve CRISPR-Cas technologies involve optimizing delivery vectors, employing viral and non-viral approaches and minimizing immunogenicity. With research in animal models providing promising results in rescuing the expression of wild-type podocin in mouse models of nephrotic syndrome and successful clinical trials in the early stages of various disorders, including cancer immunotherapy, there is hope for successful translation of genome editing to kidney diseases.
2021-02-02 | CRISPR/Cas9 engineering of albino cystinuria Type A mice.
Cystinuria Type A is a relatively common genetic kidney disease occurring in 1 in 7,000 people worldwide that results from mutation of the cystine transporter rBAT encoded by Slc3a1. We used CRISPR/Cas9 technology to engineer cystinuria Type A mice via genome editing of the C57BL/6NHsd background. These mice are an improvement on currently available models as they are on a coisogenic genetic background and have a single defined mutation. In order to use albinism to track Cas9 activity, we co-injected gRNAs targeting Slc3a1 and tyrosinase (Tyr) with Cas9 expressing plasmid DNA into mouse embryos. Two different Slc3a1 mutational alleles were derived, with homozygous mice of both demonstrating elevated urinary cystine levels, cystine crystals, and bladder stones. We used whole genome sequencing to evaluate for potential off-target editing. No off-target indels were observed for the top 10 predicted off-targets for Slc3a1 or Tyr. Therefore, we used CRISPR/Cas9 to generate coisogenic albino cystinuria Type A mice that could be used for in vivo imaging, further study, or developing new treatments of cystinuria.
2006-01-01 | 221. A New Retroviral Gene Therapy Approach for Cystinuria Research
Objectives: For cystinuria, gene therapy might provide a correction of the cellular dysfunction by expressing the deficient gene. Currently there is no stable cellular model which mimics the cystinuria phenotype and genotype to study the potential benefits of gene therapy in vitro. We initially developed an antisense expressing vector for the SLC3A1 gene using a non viral vector. To optimize the system we decided to create stable cell lines with retroviral vectors. Retroviral vectors are efficient vehicles to deliver genes into the cell and for stable integration into the genome. We used Murine leukemia virus (MLV) vector to generate a stable cell line which represents the cystinuria type 1 disease in vitro to serve as a tool for the development of gene therapy. Materials and methods: HK-2 is a proximal tubular cell (PTC) line derived from normal human kidney. The presence of the SLC3A1 (rBAT) gene was determined using the c-DNA of HK-2 cells by PCR with the SLC3A1 primers. The SLC3A1 gene was cloned into a Murine leukemia virus (MLV) transfer vector. This vector additionally contains a puromycin resistance marker. We also cloned the SLC3A1 gene in an antisense orientation to obtain a knockout of the rBAT protein by antisense RNA. Two controls were generated with mutations in the start codons of the both the sense and antisense constructs. Phoenix A is a second-generation MLV packaging cell line for the generation of helper free amphotropic retroviral vectors. Calcium phosphate was used to transfect the individual vector into the phoenix cells to generate the virus with the respective SLC3A1 constructs. The viral particles are obtained from the supernatant and filtered through a 0,45 μM filter to obtain cell-free supernatant. The four different viral supernatants are then used to transduce the target HK-2 cells in the presence of polybrene. 48 hrs post infection the HK-2 cells were subjected to puromycin selection (1 microgram/ml). After 3 days the selection pressure was removed and the cells were cultured normally. Results: The SLC3A1 gene amplified by RT-PCR from HK-2 cells in sense and anti sense orientation was analyzed by automated sequencing. The HK-2 cells after transduction with the different viral vectors and after puromycin selection were checked by PCR and Western blot for the expression of the constructs. Discussion: The stable knock down cell line representing the cystinuria type 1 can be used to validate the efficiency of gene therapy in vitro. We would transduce the stable knock down cell line of the SLC3A1 gene with a feline immunodeficiency viral (FIV) vector expressing the SLC3A1 gene to determine the efficiency of gene therapy and to compare it to the FIV based gene therapy of the cystinuria animal model in vivo.
oligonucleotides
2025-09-03 | Clinical and genotypic features, renal prognosis of orphan tubulopathies with nephrocalcinosis and cystin stones in children
THE AIM : To evaluate clinical and genotypic features, renal prognosis in orphan tubulopathies with nephrocalcinosis and cys- tine calculi in 22 pediatric patients. PATIENTS AND METHODS : The study included 22 patients (from 1 year 4 months to 17 years 11 months) with orphan tubulopathies with nephrocalcinosis (22) and cystinuria, cystine stones (2). Of the 22 probands, there were 14 (63.6 %) boys and 8 (36.4 %) girls. Clinical, biochemical, imaging, and molecular genetic diagnostic methods were used. The severity of chronic kidney disease was stratified according to the K/DOQI classification (2002). RESULTS : A genetic study of 22 children with nephrocalcinosis revealed primary hyperoxaluria of types I, II, III (AGXT, GRHPR, HOGA1) in 5; familial hypomagnesemia with hypercalciuria and nephrocalcinosis (CLDN16) in 5; hypophosphatemic rickets with hypercal- ciuria and nephrocalcinosis (SLC34A3) in 3; Bartter type I syndrome (SLC12A1) in 1 and Bartter syndrome type IV (BSND) in 1, Dent1 disease (CLCN5) in 1, Dent disease 2 (OCRL) in 1, idiopathic infantile hypercalcemia type I (SLC34A1) in 1 and type II (CYP24A1) in 2. Based on the detection of mutations in the SLC3A1 and SLC7A9 genes, 2 probands were diagnosed with type I and non type I cystinuria. The features of gene mutation variants in 22 children with orphan tubulopathies with nephrocalci- nosis and cystinuria, and cystine nodules were identified. A study of kidney function in 22 children over the age of 2 years with nephrocalcinosis and cystinuria revealed CKD C1 with normal glomerular filtration rate (17), CKD C2, C3, C4 (5). A girl with familial hypomagnesemia with hypercalciuria and nephrocalcinosis due to a mutation of the CLDN16 gene, progression CKD of С1 to C4, underwent kidney transplantation at the age of 18 before starting dialysis. CONCLUSION : Features of the clinical phenotype and variants of mutations of genes of orphan tubulopathies with nephrocalcinosis and cystinuria, cystine stones in 22 children were established. Progression of CKD from C1 with normal glomerular filtration rate to C2, C3, C4 was ascertained from 22 in 5 children (25) % with primary hyperoxaluria type1 (1), hypomagnesemia with calciuria and nephrocalcinosis (3), Dent-2 Disease (1). Identification of gene mutations in molecular genetic studies in children with nephrocalcinosis and cys- tinuria establishes a clinical and genetic diagnosis, the pathogenesis of an orphan tubulopathy, and determines personalized management based on individual genetic characteristics.
2015-09-19 | Cystinuria in a patient with 19q12q13.1 deletion
Cystinuria is a genetic cause of kidney stones with a prevalence of 1 in 7000 births. So far, two genes have been described responsible for this disorder (SLC3A1 and SLC7A9). We report a patient with an SLC7A9 gene mutation located in 19q13.1 on one allele and with a 19q12q13 region deletion on the other allele. The characteristic clinical features of the 19q13.1 microdeletion syndrome include facial dysmorphism, signs of ectodermal dysplasia, growth retardation, neurologic features and genitourinary anomalies. Cystinuria has not yet been described as part of this syndrome, although one of its responsible genes (SLC7A9) is in the same genomic location. The index case is a 6-year-old male presented with distinctive facial features, cutis aplasia of the scalp, rudimentary teeth, microcephaly, intrauterine and postnatal growth retardation, psychomotor developmental delay, speech delay, epilepsy, inguinal hernias and cystinuria. An array-CGH analysis was performed, finding a large deletion of the 19q12q13.11 cytobands, which affects 19 genes. Two of them are involved in the 19q13.11 deletion syndrome and another affected gene is SLC7A9, responsible for type B cystinuria. Sanger sequencing was performed as well, detecting a heterozygous mutation of the SLC7A9 gene, located in 19q13.1. As far as we know, this is the first described case of cystinuria in a patient with SLC7A9 gene mutation located in 19q13.1 on one allele and with 19q12q13 region deletion on the other allele. Although this patient can be classified as a type B heterozygote and, therefore, his renal prognosis is not severe, the occasional nephrolithiasis found in such patients justifies a close follow-up with regular testing of urinary cystine excretion. We suggest that the recessive behavior of this case, explains the clinical features regarding cystinuria. We propose that in the face of patients affected of a phenotype matchable with 19q13.11 syndrome and cystinuria, a mutational or sequencing study of the SLC7A9 gene should be performed to allow an early onset of diagnosis and treatment.
2008-07-01 | Evaluation of cystine transport in cultured human kidney cells and establishment of cystinuria type I phenotype by antisense technology.
Cystinuria is a rare hereditary disease resulting in recurrent stone formation and the need for repeated invasive interventions. So far, two responsible genes have been identified which encode the two transporters, rBAT and b(0,+)AT forming a heterodimer to transport cystine in proximal tubular cells (PTC) and whose defect results in increased excretion of cystine. A human cell line mimicing the phenotype of cystinuria in vitro is yet to be developed. Human kidney (HK)-2 is a PTC line derived from normal HK. After determining the presence of rBAT gene by RT-PCR and Western blot analysis, radioactively labeled cystine (S(35)) was used to evaluate the functional presence of the amino acid transport in HK-2 cells when cultured in vitro. To achieve a cystinuria type I phenotype in HK-2 cells, the rBAT gene was silenced using antisense oligonucleotides complimentary to human rBAT mRNA. The reduced transport activity of cystine was then determined by radiolabeled cystine uptake measurements. RT-PCR and Western blot confirmed the expression of the rBAT gene in HK-2 cells. Considerable transport of the radio labeled cystine was observed in HK-2 cells and was linearly dependent on the incubation time with the amino acid. The cystine transport in rBAT knockdown cells after incubation with antisense oligonucleotides was significantly lower compared to control (0.76 vs. 0.98%; P=0.0008), proving a transient knock-down of the rBAT gene. This study demonstrates the presence of the b(0,+) amino acid transport system in human proximal tubular HK-2 cells when cultured in vitro. Inhibition of this transport system is possible by using antisense technology. A permanent inhibition of the cystine transport, based on our model, would be useful for the development and evaluation gene therapeutic approaches.
Access all drug discovery papers and probability of success in trials forecasts:
Access all drug discovery papers and probability of success in trials forecasts:
Drug Discovery Landscape
0 orphan drug designations.
0 orphan drug designations.
Let's accelerate rare disease drug discovery
Let's accelerate drug discovery
Get access to Explority AI’s forecasts to outperform average preclinical success rates. Whether you’re expanding your R&D pipeline, evaluating a partnership, or simply have a question — we’d love to hear from you.