DeCure for Gamma-glutamylcysteine synthetase deficiency
DeCure's autonomous Rare AI scientist is researching a drug-repurposing hypothesis for gamma-glutamylcysteine synthetase deficiency — screening already-approved drugs against its 1-gene Open Targets disease module to publish open-access research. Research is fast; the path to publication is funded in milestone stages.
Disease moduleGamma-glutamylcysteine synthetase deficiency maps to a 1-gene Open Targets module — the target space DeCure's AI scientist screens approved drugs against.
DeCure.ai methodSignature reversal (LINCS) plus network proximity (STRING) rank already-approved drugs likely to perturb this module — the same engine that produces DeCure.ai's repurposing hypotheses.
Repurposing thesisScreening approved medicines against this disease module, then publishing the evidence for the strongest candidate. Known pharmacology and human exposure data make the first question sharper — they do not establish safety or efficacy in a new indication.
Research record
01
ResearchComing soon
Candidate research + dossier — target rationale, drug-repurposing thesis and evidence pack.proof: Published dossier + on-chain hash
02
ValidationComing soon
In-vitro biological validation at a contract research org (CRO).proof: CRO contract + in-vitro report
03
Peer review & paperComing soon
Peer-reviewed paper published open-access (preprint + journal).proof: DOI + open-access link + on-chain hash
Current lead
No approved-drug candidate for gamma-glutamylcysteine synthetase deficiency is corroborated in the literature DeepSearch retrieved. Some conditions are managed with non-pharmacological care — a device, surgery or physical therapy — rather than a medicine; that may be the case here, or the literature we found may simply be too sparse yet to support a drug-repurposing angle.
What the evidence adds up to
Gamma-glutamylcysteine synthetase deficiency is a rare inherited disorder of glutathione biosynthesis. A 2003 study identified a novel missense mutation in the catalytic subunit gene (gamma-GCSH) in two related patients: a homozygous C>T change at nucleotide 379, predicting an Arg127Cys substitution. Transfection experiments showed that this mutation decreased glutathione production, and purified recombinant mutant protein had markedly reduced enzymatic activity compared to wild type. Computer modelling placed the mutation in a surface cleft near Cys249, a conserved residue close to the substrate binding site.
Earlier reports describe conflicting clinical presentations. A 1990 case reported a woman, daughter of fifth cousins, with gamma-glutamylcysteine synthetase deficiency whose only manifestation was haemolytic anaemia. Modest decreases in glutathione were found in cultured lymphoblasts and fibroblasts, but residual enzyme was too scarce for detailed kinetic study; no major abnormality in Km for cysteine or glutamic acid, or in heat stability, was detected. This contrasts with a previous single report linking the deficiency to both spinocerebellar degeneration and haemolytic anaemia. The authors concluded that the neurological symptoms in that earlier family might be a chance association, or that the defect has pleomorphic expression.
A 2004 study on hereditary glutathione synthetase deficiency (a different enzyme in the same pathway) examined seven naturally occurring missense mutations using an E. coli expression system. Five mutations reduced Vmax to 2–27% of wild-type activity and abolished negative co-operativity for the gamma-glutamyl substrate; one mutation changed co-operativity from negative to positive. One mutation (P314L) had no major effect and was classified as neutral. These kinetic data come from glutathione synthetase, not gamma-glutamylcysteine synthetase, and cannot be directly applied to the latter deficiency.
What remains missing is systematic clinical characterisation of gamma-glutamylcysteine synthetase deficiency across more than a handful of patients. No controlled trial of any intervention has been reported. The rarity of the condition makes patient stratification difficult, and no funding for a natural history study or for developing a reliable enzyme replacement or gene therapy approach is evident from the published literature.
Evidence
Retrieved by DeepSearch across 234,678,978 indexed works and resolved on OpenAlex — ranked by citations, including the results that did not work.
Blood · 2003 · 55 citations · open access
A novel missense mutation in the γ-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production
AbstractGamma-glutamylcysteine synthetase (gamma-GCS) catalyzes the first and rate-limiting step in glutathione (GSH) biosynthesis: the adenosine triphosphate (ATP)-dependent ligation of glutamate and cysteine. gamma-GCS consists of a catalytic (gamma-GCSH) and modifier (gamma-GCSL) subunit. Hereditary deficiency of gamma-GCS has been reported in a small number of patients and is associated with low erythrocyte levels of gamma-GCS and GSH leading to hemolytic anemia. Here we report a novel gamma-GCSH mutation, isolated from the cDNA of 2 related patients diagnosed with gamma-GCS deficiency. Each was found to be homozygous for a C>T missense mutation at nucleotide 379, encoding for a predicted Arg127Cys amino acid change. Computerized structure modeling identified that the mutated amino acid lies within a cleft on the protein surface of gamma-GCSH, and the border of this cleft was shown to contain Cys249, an evolutionarily conserved residue that has been proven to lie near the binding site of gamma-GCSH. Transfection studies showed that the mutation is associated with decreased GSH production, and binding studies using purified recombinant protein showed that the mutant protein has markedly decreased enzymatic activity compared to wild type.
Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia
Abstractgamma-Glutamylcysteine synthetase is one of the enzymes of glutathione (GSH) synthesis. A deficiency of this enzyme has been found only once previously in humans: it was associated with spinocerebellar degeneration and hemolytic anemia. We report the case of a woman, daughter of fifth cousins, who was gamma-glutamylcysteine-synthetase-deficient. Modest decreases in the amount of GSH in cultured lymphoblasts and fibroblasts could be documented. The amount of residual enzyme was insufficient to permit detailed studies of the characteristics of the mutant enzymes, but no major abnormality in its Km for cysteine and glutamic acid or in its heat stability were found. In contrast to the earlier report, the only manifestation of the enzyme deficiency was hemolytic anemia. This leads us to conclude that either the occurrence of neurologic symptoms in the other reported family was a chance association or that the clinical expression of this rare defect is pleomorphic.
Biochemical Journal · 2004 · 8 citations · open access
Human hereditary glutathione synthetase deficiency: kinetic properties of mutant enzymes
AbstractPatients with hereditary glutathione synthetase deficiency suffer from haemolytic anaemia, 5-oxoprolinuria, metabolic acidosis, recurrent bacterial infections and various degrees of central nervous system dysfunction. To investigate the molecular basis of the mutations associated with this disease, seven naturally occurring missense mutations [L188P (Leu188-->Pro), D219A, D219G, Y270C, Y270H, R283C and P314L] were expressed using a His-tagged, Escherichia coli-based expression system. Effects of the mutations on kinetic properties, including negative co-operative binding of gamma-glutamyl substrate, were evaluated. The mutation P314L did not have any major effect on these parameters and was classified as a neutral mutation. The remaining mutations decreased V(max) to 2-27% of wild-type activity. Negative co-operativity for gamma-gluABA (L-gamma-glutamyl-L-alpha-aminobutyric acid) was abolished in five mutant recombinant enzymes, whereas for one mutant enzyme, this co-operativity changed from negative to positive. The structural consequences of the mutations were interpreted on the basis of the known structure of the wild-type enzyme.
Gamma-glutamylcysteine synthetase deficiency and hemolytic anemia
Abstractgamma-Glutamylcysteine synthetase is one of the enzymes of glutathione (GSH) synthesis. A deficiency of this enzyme has been found only once previously in humans: it was associated with spinocerebellar degeneration and hemolytic anemia. We report the case of a woman, daughter of fifth cousins, who was gamma-glutamylcysteine-synthetase- deficient. Modest decreases in the amount of GSH in cultured lymphoblasts and fibroblasts could be documented. The amount of residual enzyme was insufficient to permit detailed studies of the characteristics of the mutant enzymes, but no major abnormality in its Km for cysteine and glutamic acid or in its heat stability were found. In contrast to the earlier report, the only manifestation of the enzyme deficiency was hemolytic anemia. This leads us to conclude that either the occurrence of neurologic symptoms in the other reported family was a chance association or that the clinical expression of this rare defect is pleomorphic.
Disease module: DeepOracle (Open Targets). Structures: RDKit from PubChem SMILES. Literature: retrieved by DeepSearch across 234,678,978 indexed works (targeted per-candidate search), resolved on OpenAlex.
DeCure is a research and publication project, not medical advice and not a treatment. "DeCure for X" describes a research goal, not a claim that a cure exists. Backing a cure is a contribution to fund the research — it is not an investment, and confers no yield, royalty, equity or IP ownership. Papers are published open-access by the DeCure.ai DAO.
