ST8SIA3
Chr 18ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 3
Also known as: SIAT8C, ST8SiaIII
This highly constrained gene encodes a sialyltransferase that catalyzes the transfer of sialic acid to form oligosialic and polysialic acid modifications on N-linked glycoproteins and glycolipids, particularly in the striatum where it regulates protein distribution in lipid rafts. Mutations cause autosomal recessive intellectual disability with seizures and spasticity, typically presenting in early childhood. The gene shows strong intolerance to loss-of-function variants (pLI 0.86, LOEUF 0.41), suggesting haploinsufficiency is not well tolerated.
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
More LoF-intolerant than ~75% of genes
Mild missense constraint
ClinVar Variant Classifications
106 submitted variants in ClinVar
Classification Summary
Curated Variants Distribution
Classified variants from ClinVar · 5 ACMG categories
| Classification | LoF | Missense + Inframe | Non-coding | Synonymous | Total |
|---|---|---|---|---|---|
Pathogenic | 0 | 0 | 62 | 0 | 62 |
Likely Pathogenic | 0 | 0 | 2 | 0 | 2 |
VUS | 0 | 37 | 4 | 0 | 41 |
Likely Benign | 0 | 0 | 0 | 0 | 0 |
Benign | 0 | 0 | 0 | 0 | 0 |
| Total | 0 | 37 | 68 | 0 | 105 |
LoF = frameshift, stop gained/lost, canonical splice · Counts from ClinVar esearch · Updated hourly
View in ClinVar →Protein Context — Lollipop Plot
ST8SIA3 · protein map & ClinVar variants
Showing all ClinVar variants across the protein. Search a specific variant to highlight its position.
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