ASS1
Chr 9ARargininosuccinate synthase 1
Also known as: ASS, CTLN1
The protein catalyzes the penultimate step of arginine biosynthesis by synthesizing argininosuccinate from citrulline and aspartate. Mutations cause citrullinemia, an autosomal recessive disorder of the urea cycle that results in hyperammonemia and elevated plasma citrulline levels. The pathogenic mechanism involves loss of enzyme function leading to impaired conversion of citrulline to argininosuccinate in the cytosol.
Definitive — sufficient evidence for diagnostic panels
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Typical tolerance to LoF variation
Mild missense constraint
Predictions shown for reference only — model trained on dominant genes, not applicable to AR conditions.
The Badonyi & Marsh prediction model was trained exclusively on dominant disease genes. Predictions are not reliable for genes with autosomal recessive inheritance and are shown at reduced opacity for reference only.
Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.
ClinVar Variant Classifications
0 submitted variants in ClinVar
Protein Context — Lollipop Plot
ASS1 · protein map & ClinVar variants
Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.
3D Protein StructureAlphaFold
External Resources
Links to major genomics databases and tools
Clinical Trials
Active and recruiting trials from ClinicalTrials.gov
No active trials found for this gene.
Search ClinicalTrials.gov →External Resources
Links to major genomics databases and tools