COL18A1
Chr 21ADARcollagen type XVIII alpha 1 chain
Also known as: GLCC, KNO, KNO1, KS
The COL18A1 gene encodes the alpha chain of type XVIII collagen, an extracellular matrix protein that undergoes proteolytic processing to produce endostatin, an antiangiogenic protein, and plays a major role in determining retinal structure and neural tube closure. Mutations cause Knobloch syndrome type 1 (characterized by retinal abnormalities and occipital encephalocele) and primary closed-angle glaucoma, with both autosomal recessive and autosomal dominant inheritance patterns reported. The gene shows moderate constraint against loss-of-function variants (LOEUF 0.535), indicating some tolerance to complete gene disruption.
Definitive — sufficient evidence for diagnostic panels
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
More LoF-intolerant than ~75% of genes
Tolerant to missense variation
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
COL18A1 · 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