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CNTNAP2
contactin associated protein 2
CNTNAP2 is located on the long (q) arm of chromosome 7, at band 7q35-q36.1. Arm ratio per GRCh38 - banding schematic.
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Overview
CNTNAP2 is located on chromosome 7 and encodes a member of the neurexin superfamily of cell-adhesion molecules. The protein plays a role in organising voltage-gated potassium channels at nodes of Ranvier - specialised regions along nerve fibres that enable rapid signal transmission. Beyond this structural role, research suggests the protein influences neuronal migration and the formation of synaptic connections during development. Variation in CNTNAP2 follows a polygenic pattern, meaning that multiple genetic and environmental factors contribute to associated traits. The gene has been studied extensively in the context of language development and neurodevelopmental conditions, though individual variants typically confer modest effects rather than deterministic outcomes.
What the gene does
Contactin-associated protein 2 functions primarily as a cell-adhesion molecule at the neuronal cell surface. It interacts with contactin 2, a related protein, to cluster potassium channels at the juxtaparanodal regions flanking nodes of Ranvier, thereby maintaining the electrical insulation required for efficient nerve impulse conduction. The protein also participates in organising GABAergic interneuron networks - inhibitory circuits that regulate the balance of excitation and inhibition in the developing brain. Evidence suggests that contactin-associated protein 2 influences dendritic arborisation and the migration of cortical interneurons during embryonic development. These functions position the protein as a regulator of neural circuit assembly, particularly in regions associated with language and social cognition. Disruption of these processes may alter synaptic connectivity and network dynamics in ways that increase susceptibility to neurodevelopmental variation.
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Chromosome location
CNTNAP2 is located at chromosome band 7q35-q36.1. The gene spans approximately 2.3 megabases, making it one of the largest genes in the human genome. It contains 24 exons that encode a transcript of approximately 4,000 nucleotides. The extended genomic footprint reflects the complexity of regulatory elements controlling expression in different brain regions and developmental stages.
Protein structure
The 1,331-amino-acid protein comprises multiple extracellular domains characteristic of the neurexin family. The N-terminal region includes an F5/8 type C domain (amino acids 35-181) followed by four laminin G-like domains interspersed along the sequence: laminin G-like 1 (amino acids 216-368), laminin G-like 2 (amino acids 401-552), laminin G-like 3 (amino acids 799-963), and laminin G-like 4 (amino acids 1,055-1,214). Two EGF-like domains appear at amino acids 554-591 and 963-1,002. A fibrinogen C-terminal domain spans amino acids 592-798, contributing to protein-protein interactions. A disordered region is present at amino acids 1,026-1,045. This modular architecture enables multivalent binding to extracellular partners, supporting the protein's role in assembling macromolecular complexes at the cell surface.
Key variants
Genetic variation in CNTNAP2 includes both common polymorphisms and rare sequence changes. Common variants across the gene have been examined in large population studies for association with language ability, reading skills, and autism-related traits, though effect sizes are generally small. Rare coding variants, including missense and truncating changes, have been identified in individuals with epilepsy, intellectual disability, and autism spectrum disorder. The polygenic nature of these associations means that individual variants contribute to risk in the context of other genetic and environmental factors rather than acting alone.
Sample of pathogenic variants
10 pathogenic / likely-pathogenic variants from ClinVar, ranked by review status (expert-panel-reviewed first). This is a sample; recurrent founder variants in a specific population may not appear here - see the full ClinVar listing via the link above.
| Variant (HGVS) | Protein change | Classification | Evidence | Associated condition |
|---|---|---|---|---|
c.1361_1362del | p.Asn454fs | Pathogenic/Likely pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.1843dup | p.Asp615fs | Pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.2101G>T | p.Gly701Ter | Pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.2646G>A | p.Trp882Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.3262C>T | p.Arg1088Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.3283C>T | p.Arg1095Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.3331C>T | p.Gln1111Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Inborn genetic diseases |
c.3556dup | p.Gln1186fs | Pathogenic | ★★☆☆ | Inborn genetic diseases |
c.551G>A | p.Trp184Ter | Pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
c.682G>T | p.Gly228Ter | Pathogenic/Likely pathogenic | ★★☆☆ | Cortical dysplasia-focal epilepsy syndrome |
Evidence stars indicate ClinVar review status. Individual variant interpretation should always be performed by a qualified clinical laboratory - many variants remain classified as Variants of Uncertain Significance (VUS) pending more research.
Associated conditions
CNTNAP2 variation has been linked to a spectrum of neurodevelopmental phenotypes. Research has identified associations with autism spectrum disorder, language delay, epilepsy (particularly focal seizures), and intellectual disability. Some rare recessive variants are associated with cortical dysplasia-focal epilepsy syndrome, a condition characterised by abnormal brain development and seizure activity. However, many individuals carrying CNTNAP2 variants do not develop clinical features, reflecting the polygenic architecture and incomplete penetrance typical of complex neuropsychiatric traits. The gene's involvement spans a continuum from typical variation in language skills to more pronounced developmental challenges.
No disease links recorded for this gene in our reference set.
UK clinical status
CNTNAP2 appears on several NHS Genomic Medicine Service gene panels. It is included in the Early Onset or Syndromic Epilepsy panel (R59, green classification), the Fetal Anomalies panel (R21, green classification), and the Intellectual Disability panel (R29, green classification). Green classification indicates a sufficient evidence base linking the gene to the respective conditions. The gene is also listed in the Developmental Disorders Genotype-to-Phenotype (DDG2P) database with green confidence, supporting its role in developmental presentations. These panel memberships reflect the gene's established relevance in clinical genomic investigations of neurodevelopmental and epilepsy phenotypes within the NHS.
Sources: NHS GMS PanelApp · Genomics England PanelApp · NHS National Genomic Test Directory
Frequently asked questions
What does the CNTNAP2 gene do?
CNTNAP2 encodes a neuronal cell-adhesion protein that organises potassium channels along nerve fibres and helps assemble inhibitory circuits in the developing brain. These functions support efficient nerve signalling and the formation of neural networks involved in language and cognition.
Is CNTNAP2 associated with autism?
Research has identified associations between CNTNAP2 variation and autism spectrum disorder traits, though the relationship is polygenic and influenced by multiple genetic and environmental factors. Individual variants typically confer modest effects rather than determining outcomes.
How is CNTNAP2 used in UK clinical genetics?
CNTNAP2 is included on NHS gene panels for early-onset epilepsy, foetal anomalies, and intellectual disability, with green classification indicating established evidence. Variants in this gene may be reported as part of genomic investigations for neurodevelopmental presentations.