RARE DISEASE
Argininosuccinic aciduria
Argininosuccinic aciduria
Argininosuccinic aciduria
Synonyms: ASA deficiency, ASL deficiency, Argininosuccinase deficiency, Argininosuccinatelyase deficiency, Argininosuccinic acid lyase deficiency
Synonyms: ASA deficiency, ASL deficiency, Argininosuccinase deficiency, Argininosuccinatelyase deficiency, Argininosuccinic acid lyase deficiency
Synonyms: ASA deficiency, ASL deficiency, Argininosuccinase deficiency, Argininosuccinatelyase deficiency, Argininosuccinic acid lyase deficiency
Drug discovery
10
drugs
With orphan designations
Overview
Argininosuccinic aciduria (ASA) is an autosomal recessive urea cycle disorder caused by argininosuccinate lyase deficiency, leading to impaired ammonia detoxification and hyperammonemia. It presents as neonatal-onset (lethargy, vomiting, seizures) or late-onset (stress-induced hyperammonemia, neurocognitive deficits). Chronic complications include liver dysfunction, hypertension, and trichorrhexis nodosa. Diagnosis involves elevated ammonia, citrulline, and argininosuccinic acid levels, confirmed by genetic testing [1][13][16].
Categories: rare genetic diseases, rare inborn errors of metabolism, rare neurological diseases
Research Papers
104 drug discovery papers about Argininosuccinic aciduria, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
104 drug discovery papers about Argininosuccinic aciduria, with 2 first-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-03-19 | Impact of long-term nitrogen scavenger therapy on clinical outcome in individuals with urea cycle disorders.
Principles of long-term medical management in individuals with urea cycle disorders (UCDs) encompass (1) a low protein diet, (2) supplementation of arginine and/or citrulline along with essential amino acids, nutrients, vitamins and trace elements, and (3) use of nitrogen scavenging agents to reduce recurrent hyperammonemic events (HAEs). These principles aim at providing metabolic stability, elimimation of chronic complications, and achievement of normal development as well as growth. A retrospective comparative analysis was performed by studying 138 individuals with male ornithine transcarbamylase deficiency (mOTC-D), citrullinemia type 1 (CTLN1) and argininosuccinic aciduria (ASA) based on in vitro residual enzymatic activity for severity-adjustment. Results show that individuals with mOTC-D, CTLN1 and ASA are at risk of progressive linear growth impairment, recurrent annual HAEs and an unfavorable neurocognitive outcome despite being under long-term nitrogen scavenging pharmacotherapy. No overall superiority among existing nitrogen scavenging agents with regard to the individual's metabolic stability, linear growth impairment and poor neurocognitive outcome was observed. Novel therapeutic strategies are urgently needed to ultimately improve health outcomes in individuals with UCDs in order to sufficiently meet guideline-specific goals.
2025-01-08 | Positive Clinical, Neuropsychological, and Metabolic Impact of Liver Transplantation in Patients With Argininosuccinate Lyase Deficiency.
Liver transplantation (LTx) is increasingly used in Urea Cycle Defects (UCDs) to prevent recurrent hyperammonemia and related neurological irreversible injury. Among UCDs, argininosuccinate lyase deficiency (ASLD) has a more complex phenotype than other UCDs, with long-term neurocognitive deficits. Therefore, the role of LTx in ASLD is still debated. The impact of LTx on nine patients with early-onset ASLD was assessed through pre- and post-LTx clinical, neuropsychological, MRI and biochemical evaluations. After LTx, no episodes of metabolic decompensations were reported. Neuropsychological evaluations documented significant improvement in cognitive/developmental functioning especially in patients transplanted in early childhood. Improvements were also highlighted in daily living skills and emotional-behavioral problems, with a reduction in attention disturbances and somatic complaints. Movement disorders resolved after LTx in patient transplanted in early childhood. Any patients developed epilepsy with stability of EEG alterations after LTx. A positive effect of LTx on other disease-related outcomes such as growth, diet, medications, hospitalizations, and long-term ASLD-related complications was highlighted. The primary biomarker argininosuccinic acid dramatically reduced in plasma after transplantation with a decreasing trend in CSF at long-term follow-up. Moreover, health-related quality of life improved after LTx, especially when assessed through MetabQoL, a tool designed for intoxication diseases such as ASLD. In conclusion, our study showed a global beneficial impact of LTx in early-onset ASLD patients to avoid episodes of hyperammonemia, and improve neurocognitive outcome, adaptive and behavioral deficits when performed in early childhood with a dramatic benefit in terms of quality of life.
2024-04-08 | Genetic and functional correction of argininosuccinate lyase deficiency using CRISPR adenine base editors.
Argininosuccinate lyase deficiency (ASLD) is a recessive metabolic disorder caused by variants in ASL. In an essential step in urea synthesis, ASL breaks down argininosuccinate (ASA), a pathognomonic ASLD biomarker. The severe disease forms lead to hyperammonemia, neurological injury, and even early death. The current treatments are unsatisfactory, involving a strict low-protein diet, arginine supplementation, nitrogen scavenging, and in some cases, liver transplantation. An unmet need exists for improved, efficient therapies. Here, we show the potential of a lipid nanoparticle-mediated CRISPR approach using adenine base editors (ABEs) for ASLD treatment. To model ASLD, we first generated human-induced pluripotent stem cells (hiPSCs) from biopsies of individuals homozygous for the Finnish founder variant (c.1153C>T [p.Arg385Cys]) and edited this variant using the ABE. We then differentiated the hiPSCs into hepatocyte-like cells that showed a 1,000-fold decrease in ASA levels compared to those of isogenic non-edited cells. Lastly, we tested three different FDA-approved lipid nanoparticle formulations to deliver the ABE-encoding RNA and the sgRNA targeting the ASL variant. This approach efficiently edited the ASL variant in fibroblasts with no apparent cell toxicity and minimal off-target effects. Further, the treatment resulted in a significant decrease in ASA, to levels of healthy donors, indicating restoration of the urea cycle. Our work describes a highly efficient approach to editing the disease-causing ASL variant and restoring the function of the urea cycle. This method relies on RNA delivered by lipid nanoparticles, which is compatible with clinical applications, improves its safety profile, and allows for scalable production.
2024-03-11 | Impact of supplementation with L-citrulline/arginine after liver transplantation in individuals with Urea Cycle Disorders.
Liver transplantation (LTx) is an intervention when medical management is not sufficiently preventing individuals with urea cycle disorders (UCDs) from the occurrence of hyperammonemic events. Supplementation with L-citrulline/arginine is regularly performed prior to LTx to support ureagenesis and is often continued after the intervention. However, systematic studies assessing the impact of long-term L-citrulline/arginine supplementation in individuals who have undergone LTx is lacking to date. Using longitudinal data collected systematically, a comparative analysis was carried out by studying the effects of long-term L-citrulline/arginine supplementation vs. no supplementation on health-related outcome parameters (i.e., anthropometric, neurological, and cognitive outcomes) in individuals with UCDs who have undergone LTx. Altogether, 52 individuals with male ornithine transcarbamylase deficiency, citrullinemia type 1 and argininosuccinic aciduria and a pre-transplant "severe" disease course who have undergone LTx were investigated by using recently established and validated genotype-specific in vitro enzyme activities. Long-term supplementation of individuals with L-citrulline/arginine who have undergone LTx (n = 16) does neither appear to alter anthropometric nor neurocognitive endpoints when compared to their severity-adjusted counterparts that were not supplemented (n = 36) after LTx with mean observation periods between four to five years. Moreover, supplementation with L-citrulline/arginine was not associated with an increase of disease-specific plasma arithmetic mean values for the respective amino acids when compared to the non-supplemented control cohort. Although supplementation with L-citrulline/arginine is often continued after LTx, this pilot study does neither identify altered long-term anthropometric or neurocognitive health-related outcomes nor does it find an adequate biochemical response as reflected by the unaltered plasma arithmetic mean values for L-citrulline or L-arginine. Further prospective analyses in larger samples and even longer observation periods will provide more insight into the usefulness of long-term supplementation with L-citrulline/arginine for individuals with UCDs who have undergone LTx.
2023-12-04 | Transition to glycerol phenylbutyrate for the management of urea cycle disorders: clinical experiences.
Urea cycle disorders (UCDs) are a group of rare inborn diseases caused by a deficiency in one of the six enzymes or one of the two transporters involved in the urea cycle. The most common biochemical feature is elevated blood ammonia levels, which can be toxic at high levels, especially to the brain and may manifest as encephalopathy if left untreated. Glycerol phenylbutyrate (GPB) is currently approved for use in the USA and Europe for patients of all ages with UCD who cannot be managed with protein restriction and/or amino acid supplementation alone. This article presents the author's experience in different exemplary settings and depicts the most efficient management of UCDs with GPB. Six patient histories are described. 4 had OCT, one citrullinemia, and one argininosuccinic aciduria. Treatment with GPB was started between 2 days and 14 years of age. Before GPB, one patient had not been treated, 4 had received sodium phenylbutyrate (NaPB), and one Na benzoate. Overall, treatment with GPB was followed by a relevant metabolic improvement, resulting in better therapeutic compliance, reduced hospitalization, and improved quality of life.
2026-03-19 | Impact of long-term nitrogen scavenger therapy on clinical outcome in individuals with urea cycle disorders.
Principles of long-term medical management in individuals with urea cycle disorders (UCDs) encompass (1) a low protein diet, (2) supplementation of arginine and/or citrulline along with essential amino acids, nutrients, vitamins and trace elements, and (3) use of nitrogen scavenging agents to reduce recurrent hyperammonemic events (HAEs). These principles aim at providing metabolic stability, elimimation of chronic complications, and achievement of normal development as well as growth. A retrospective comparative analysis was performed by studying 138 individuals with male ornithine transcarbamylase deficiency (mOTC-D), citrullinemia type 1 (CTLN1) and argininosuccinic aciduria (ASA) based on in vitro residual enzymatic activity for severity-adjustment. Results show that individuals with mOTC-D, CTLN1 and ASA are at risk of progressive linear growth impairment, recurrent annual HAEs and an unfavorable neurocognitive outcome despite being under long-term nitrogen scavenging pharmacotherapy. No overall superiority among existing nitrogen scavenging agents with regard to the individual's metabolic stability, linear growth impairment and poor neurocognitive outcome was observed. Novel therapeutic strategies are urgently needed to ultimately improve health outcomes in individuals with UCDs in order to sufficiently meet guideline-specific goals.
2025-01-08 | Positive Clinical, Neuropsychological, and Metabolic Impact of Liver Transplantation in Patients With Argininosuccinate Lyase Deficiency.
Liver transplantation (LTx) is increasingly used in Urea Cycle Defects (UCDs) to prevent recurrent hyperammonemia and related neurological irreversible injury. Among UCDs, argininosuccinate lyase deficiency (ASLD) has a more complex phenotype than other UCDs, with long-term neurocognitive deficits. Therefore, the role of LTx in ASLD is still debated. The impact of LTx on nine patients with early-onset ASLD was assessed through pre- and post-LTx clinical, neuropsychological, MRI and biochemical evaluations. After LTx, no episodes of metabolic decompensations were reported. Neuropsychological evaluations documented significant improvement in cognitive/developmental functioning especially in patients transplanted in early childhood. Improvements were also highlighted in daily living skills and emotional-behavioral problems, with a reduction in attention disturbances and somatic complaints. Movement disorders resolved after LTx in patient transplanted in early childhood. Any patients developed epilepsy with stability of EEG alterations after LTx. A positive effect of LTx on other disease-related outcomes such as growth, diet, medications, hospitalizations, and long-term ASLD-related complications was highlighted. The primary biomarker argininosuccinic acid dramatically reduced in plasma after transplantation with a decreasing trend in CSF at long-term follow-up. Moreover, health-related quality of life improved after LTx, especially when assessed through MetabQoL, a tool designed for intoxication diseases such as ASLD. In conclusion, our study showed a global beneficial impact of LTx in early-onset ASLD patients to avoid episodes of hyperammonemia, and improve neurocognitive outcome, adaptive and behavioral deficits when performed in early childhood with a dramatic benefit in terms of quality of life.
2024-04-08 | Genetic and functional correction of argininosuccinate lyase deficiency using CRISPR adenine base editors.
Argininosuccinate lyase deficiency (ASLD) is a recessive metabolic disorder caused by variants in ASL. In an essential step in urea synthesis, ASL breaks down argininosuccinate (ASA), a pathognomonic ASLD biomarker. The severe disease forms lead to hyperammonemia, neurological injury, and even early death. The current treatments are unsatisfactory, involving a strict low-protein diet, arginine supplementation, nitrogen scavenging, and in some cases, liver transplantation. An unmet need exists for improved, efficient therapies. Here, we show the potential of a lipid nanoparticle-mediated CRISPR approach using adenine base editors (ABEs) for ASLD treatment. To model ASLD, we first generated human-induced pluripotent stem cells (hiPSCs) from biopsies of individuals homozygous for the Finnish founder variant (c.1153C>T [p.Arg385Cys]) and edited this variant using the ABE. We then differentiated the hiPSCs into hepatocyte-like cells that showed a 1,000-fold decrease in ASA levels compared to those of isogenic non-edited cells. Lastly, we tested three different FDA-approved lipid nanoparticle formulations to deliver the ABE-encoding RNA and the sgRNA targeting the ASL variant. This approach efficiently edited the ASL variant in fibroblasts with no apparent cell toxicity and minimal off-target effects. Further, the treatment resulted in a significant decrease in ASA, to levels of healthy donors, indicating restoration of the urea cycle. Our work describes a highly efficient approach to editing the disease-causing ASL variant and restoring the function of the urea cycle. This method relies on RNA delivered by lipid nanoparticles, which is compatible with clinical applications, improves its safety profile, and allows for scalable production.
2024-03-11 | Impact of supplementation with L-citrulline/arginine after liver transplantation in individuals with Urea Cycle Disorders.
Liver transplantation (LTx) is an intervention when medical management is not sufficiently preventing individuals with urea cycle disorders (UCDs) from the occurrence of hyperammonemic events. Supplementation with L-citrulline/arginine is regularly performed prior to LTx to support ureagenesis and is often continued after the intervention. However, systematic studies assessing the impact of long-term L-citrulline/arginine supplementation in individuals who have undergone LTx is lacking to date. Using longitudinal data collected systematically, a comparative analysis was carried out by studying the effects of long-term L-citrulline/arginine supplementation vs. no supplementation on health-related outcome parameters (i.e., anthropometric, neurological, and cognitive outcomes) in individuals with UCDs who have undergone LTx. Altogether, 52 individuals with male ornithine transcarbamylase deficiency, citrullinemia type 1 and argininosuccinic aciduria and a pre-transplant "severe" disease course who have undergone LTx were investigated by using recently established and validated genotype-specific in vitro enzyme activities. Long-term supplementation of individuals with L-citrulline/arginine who have undergone LTx (n = 16) does neither appear to alter anthropometric nor neurocognitive endpoints when compared to their severity-adjusted counterparts that were not supplemented (n = 36) after LTx with mean observation periods between four to five years. Moreover, supplementation with L-citrulline/arginine was not associated with an increase of disease-specific plasma arithmetic mean values for the respective amino acids when compared to the non-supplemented control cohort. Although supplementation with L-citrulline/arginine is often continued after LTx, this pilot study does neither identify altered long-term anthropometric or neurocognitive health-related outcomes nor does it find an adequate biochemical response as reflected by the unaltered plasma arithmetic mean values for L-citrulline or L-arginine. Further prospective analyses in larger samples and even longer observation periods will provide more insight into the usefulness of long-term supplementation with L-citrulline/arginine for individuals with UCDs who have undergone LTx.
2023-12-04 | Transition to glycerol phenylbutyrate for the management of urea cycle disorders: clinical experiences.
Urea cycle disorders (UCDs) are a group of rare inborn diseases caused by a deficiency in one of the six enzymes or one of the two transporters involved in the urea cycle. The most common biochemical feature is elevated blood ammonia levels, which can be toxic at high levels, especially to the brain and may manifest as encephalopathy if left untreated. Glycerol phenylbutyrate (GPB) is currently approved for use in the USA and Europe for patients of all ages with UCD who cannot be managed with protein restriction and/or amino acid supplementation alone. This article presents the author's experience in different exemplary settings and depicts the most efficient management of UCDs with GPB. Six patient histories are described. 4 had OCT, one citrullinemia, and one argininosuccinic aciduria. Treatment with GPB was started between 2 days and 14 years of age. Before GPB, one patient had not been treated, 4 had received sodium phenylbutyrate (NaPB), and one Na benzoate. Overall, treatment with GPB was followed by a relevant metabolic improvement, resulting in better therapeutic compliance, reduced hospitalization, and improved quality of life.
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
10 orphan drug designations for Argininosuccinic aciduria, including 1 approved therapy.
10 orphan drug designations for Argininosuccinic aciduria, including 1 approved therapy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
sodium nitrite | small molecules | FDA | 2026-08-22 | — | Bryan Therapeutics |
Heterologous human adult liver-derived stem cells | cell therapies | EMA | 2022-03-16 | — | Unicyte S.R.L. |
Sodium benzoate, sodium phenylacetate | small molecules | EMA | 2019-06-28 | — | Dipharma B.V. |
Modified messenger ribonucleic acid encoding human argininosuccinate lyase enzyme encapsulated into lipid nanoparticles | RNAs | EMA | 2017-12-12 | — | PhaseRx Ireland, Ltd |
mRNA encoding human argininosuccinate lyase | RNAs | FDA | 2017-09-18 | — | PhaseRx, Inc. |
Sodium benzoate | small molecules | EMA | 2016-11-18 | — | Lucane Pharma SA |
Sodium benzoate | small molecules | EMA | 2016-01-11 | — | Syri Pharma Limited |
Heterologous human adult liver-derived progenitor cells | cell therapies | EMA | 2013-07-17 | — | Cellaion |
Human heterologous liver cells (for infusion) | cell therapies | EMA | 2010-12-17 | — | Promethera Biosciences |
Glyceryl tri-(4-phenylbutyrate) [Ravicti] | small molecules | EMA | 2010-06-10 | 2015-12-01 | Immedica Pharma AB |
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