CA9
Chr 9carbonic anhydrase 9
Also known as: CAIX, MN
CA9 encodes a transmembrane carbonic anhydrase that catalyzes the interconversion between carbon dioxide and water and the dissociated ions of carbonic acid (bicarbonate and hydrogen ions). Mutations cause autosomal recessive cerebral ataxia, mental retardation, and disequilibrium syndrome 4 (CAMRQ4), characterized by early-onset cerebellar dysfunction and intellectual disability. This gene is highly tolerant to loss-of-function variants in the general population (low constraint), which is consistent with its autosomal recessive inheritance pattern.
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Highly tolerant — LoF variants common in population
Mild missense constraint
This gene has evidence for multiple mechanisms of pathogenicity (dominant-negative and gain-of-function). Both the Badonyi & Marsh prediction and the broader genomic evidence point to dominant-negative as the predominant mechanism. Different variants in this gene may act through different mechanisms — interpret in context of the specific variant.
Note: In-silico variant effect predictors (SIFT, PolyPhen, REVEL, CADD) may underestimate pathogenicity of missense variants in genes with GOF or DN mechanisms. Consider functional evidence and clinical context.
Predictions from Badonyi M, Marsh JA. PLoS ONE. 2024;19(8):e0307312.
ClinVar Variant Classifications
0 submitted variants in ClinVar
Protein Context — Lollipop Plot
CA9 · 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
External Resources
Links to major genomics databases and tools