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SNAP29
synaptosome associated protein 29
SNAP29 is located on the long (q) arm of chromosome 22, at band 22q11.21. Arm ratio per GRCh38 - banding schematic.
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Overview
SNAP29 belongs to the SNARE protein family, which orchestrates the fusion of membrane-bound compartments within cells. This fusion machinery is fundamental to numerous cellular processes, including the degradation of damaged components through autophagy, the development and maintenance of the nervous system, and the formation of the skin barrier. Genetic variants in SNAP29 play dual roles in human health: common variants contribute incrementally to polygenic neuropsychiatric traits, whilst rare pathogenic changes cause distinct developmental syndromes characterised by intellectual disability, skin abnormalities, and impaired autophagy.
What the gene does
The SNAP29 protein facilitates membrane fusion by acting as a molecular bridge between different cellular compartments. It belongs to the t-SNARE subgroup, partnering with other SNARE proteins to form tight complexes that bring membranes into close proximity, enabling them to merge. This function is particularly important during autophagy, the cellular recycling process whereby damaged organelles and misfolded proteins are enclosed in double-membrane structures called autophagosomes, which then fuse with lysosomes for degradation. SNAP29 mediates this autophagosome-lysosome fusion step, ensuring efficient cellular quality control. Beyond autophagy, the protein participates in vesicle trafficking pathways that support neurotransmitter release at synapses and contribute to the formation of lamellar granules in skin cells, structures that deposit lipids essential for the skin's protective barrier.
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Chromosome location
SNAP29 is located on chromosome 22 at band q11.21, a region that has been associated with copy number variations affecting neurodevelopment. The gene spans multiple exons encoding a 258-amino-acid protein. This chromosomal region is clinically significant, as deletions encompassing SNAP29 and neighbouring genes can contribute to developmental phenotypes, though isolated SNAP29 variants produce distinct clinical features.
Protein structure
The SNAP29 protein contains several structural features that enable its function in membrane fusion. The N-terminal portion includes a disordered region spanning amino acids 1-41, followed by a coiled-coil domain at positions 76-107 that likely mediates protein-protein interactions. A second disordered region occupies amino acids 150-191, providing flexibility in the protein structure. The C-terminal segment contains a t-SNARE coiled-coil homology domain extending from amino acid 196 to 258, which forms the characteristic alpha-helical bundles that interact with partner SNARE proteins to drive membrane fusion events. These coiled-coil regions are essential for assembling the four-helix bundle complexes that physically bring membranes together.
Key variants
Genetic variation in SNAP29 ranges from common single-nucleotide polymorphisms that contribute to polygenic neuropsychiatric risk to rare pathogenic variants causing monogenic disease. Pathogenic changes typically involve loss-of-function mutations that severely impair or abolish SNAP29 protein activity, disrupting autophagy and other membrane fusion processes. Because SNAP29 variants contribute to polygenic traits, individual genetic changes generally have small effects that combine with variants in other genes to influence overall risk.
No pathogenic or likely-pathogenic ClinVar variants recorded yet for this gene.
Associated conditions
Rare biallelic pathogenic variants in SNAP29 cause Vici syndrome, a severe multisystem disorder characterised by absent corpus callosum, cataracts, skin hypopigmentation, immune deficiency, and progressive cardiomyopathy. This condition reflects the critical role of SNAP29 in autophagy across multiple tissues. Pathogenic variants also associate with isolated or combined features including intellectual disability, cortical malformations, and skin conditions such as ichthyosis and palmoplantar keratoderma. In the polygenic context, common SNAP29 variants contribute incrementally to neuropsychiatric trait variation in the general population, though individual variant effects are modest.
No disease links recorded for this gene in our reference set.
UK clinical status
SNAP29 appears on multiple NHS Genomic Medicine Service gene panels, reflecting its relevance to diverse clinical presentations. The gene holds green classification status on the DDG2P panel and panels for intellectual disability, malformations of cortical development, and Vici syndrome and other autophagy disorders. It is also included in panels for ichthyosis and erythrokeratoderma, palmoplantar keratoderma and erythrokeratodermas, and palmoplantar keratodermas. Green status indicates strong evidence supporting the gene-disease relationship, meaning variants in SNAP29 are routinely assessed in NHS diagnostic pathways for patients presenting with relevant clinical features.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the SNAP29 protein do in cells?
SNAP29 helps cellular compartments fuse together by forming molecular bridges with other SNARE proteins. This fusion process is essential for autophagy (cellular recycling), neurotransmitter release, and skin barrier formation.
How do SNAP29 variants affect health?
Common variants contribute small effects to polygenic neuropsychiatric traits, whilst rare pathogenic variants cause monogenic conditions like Vici syndrome, characterised by developmental abnormalities affecting the brain, eyes, skin, immune system, and heart.
Is SNAP29 tested on the NHS?
Yes, SNAP29 is included on multiple NHS gene panels with green classification, meaning it is routinely analysed for patients with intellectual disability, cortical malformations, autophagy disorders, and specific skin conditions.