AP1S1
Chr 7ARadaptor related protein complex 1 subunit sigma 1
Also known as: AP19, CLAPS1, EKV3, MEDNIK, SIGMA1A
The AP1S1 protein is a subunit of the clathrin-associated adaptor protein complex 1 that mediates protein sorting in the late-Golgi/trans-Golgi network and endosomes by recruiting clathrin to membranes and recognizing sorting signals in transmembrane cargo molecules. Mutations cause MEDNIK syndrome, a multisystem disorder affecting mental retardation, enteropathy, deafness, neuropathy, ichthyosis, and keratoderma. This condition follows autosomal recessive inheritance.
Definitive — sufficient evidence for diagnostic panels
Population Genetics & Constraint
gnomAD v4 — loss-of-function & missense intolerance
Typical tolerance to LoF variation
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
AP1S1 · 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