{"gene":"KCTD3","run_date":"2026-04-28T18:30:27","timeline":{"discoveries":[{"year":2013,"finding":"KCTD3 specifically binds to the C-terminus of HCN3 (but not other HCN family members) and functions as an accessory subunit that profoundly up-regulates cell surface expression and current density of HCN3. The C-terminal half of KCTD3 is sufficient for binding, but the complete protein including the N-terminal tetramerization domain is required for HCN3 current up-regulation. Replacement of the cytosolic C-terminus of HCN2 with the HCN3 C-terminus confers KCTD3 sensitivity, demonstrating the HCN3 C-terminus is the critical interaction domain.","method":"Co-immunoprecipitation, heterologous expression, electrophysiology, domain-swap mutagenesis, immunohistochemistry/colocalization in brain","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1–2 — multiple orthogonal methods (Co-IP, electrophysiology, mutagenesis, domain swaps) in a single rigorous study establishing mechanism","pmids":["23382386"],"is_preprint":false},{"year":2000,"finding":"SETA (an alias/related protein context; relevant insofar as KCTD3/SB1 is identified as a binding partner): A novel gene SB1 (SETA binding protein 1), identified as sharing 55% amino acid identity with the renal tumor antigen NY-REN-45, was found to bind SETA via its SH3 domain, confirmed by in vitro confrontation and co-immunoprecipitation.","method":"Yeast two-hybrid screening, in vitro binding assay, co-immunoprecipitation","journal":"Cellular signalling","confidence":"Low","confidence_rationale":"Tier 3 — SB1/NY-REN-45 identity to KCTD3 is not explicitly confirmed; the paper does not directly characterize KCTD3 function, only identifies it as a binding partner of SETA","pmids":["11152963"],"is_preprint":false},{"year":2018,"finding":"Biallelic loss-of-function mutations in KCTD3 cause a consistent phenotype of developmental epileptic encephalopathy, global developmental delay, hypotonia, and posterior fossa/cerebellar abnormalities, establishing KCTD3 as required for normal brain and cerebellar development.","method":"Whole exome sequencing with segregation analysis in four consanguineous families (7 affected individuals)","journal":"Clinical genetics","confidence":"Medium","confidence_rationale":"Tier 2 — clean loss-of-function human genetics with defined phenotypic readout, replicated across multiple families; no in vitro mechanism","pmids":["29406573"],"is_preprint":false}],"current_model":"KCTD3 functions as an accessory subunit of the HCN3 ion channel, binding specifically to the HCN3 C-terminus via its own C-terminal half and requiring its N-terminal tetramerization domain to up-regulate HCN3 cell surface expression and current density; biallelic loss-of-function mutations in humans cause developmental epileptic encephalopathy with cerebellar abnormalities, consistent with its high expression in brain and kidney."},"narrative":{"teleology":[{"year":2000,"claim":"Before KCTD3's molecular function was known, a yeast two-hybrid screen identified a protein (SB1/NY-REN-45, sharing identity with KCTD3) as an SH3-domain binding partner of the adaptor protein SETA, suggesting KCTD3 participates in protein–protein interactions but leaving its physiological role unresolved.","evidence":"Yeast two-hybrid, in vitro binding, and co-immunoprecipitation with SETA","pmids":["11152963"],"confidence":"Low","gaps":["The identity of SB1/NY-REN-45 with KCTD3 is not explicitly confirmed in this study","No functional consequence of the SETA–SB1 interaction was demonstrated","No independent validation of this interaction has been reported"]},{"year":2013,"claim":"The key mechanistic question — what ion channel or signaling pathway KCTD3 regulates — was answered by demonstrating that KCTD3 is a specific accessory subunit of HCN3, binding its C-terminus and profoundly enhancing its surface expression and current density through a mechanism requiring KCTD3 tetramerization.","evidence":"Co-immunoprecipitation, heterologous expression electrophysiology, domain-swap mutagenesis, and brain colocalization immunohistochemistry","pmids":["23382386"],"confidence":"High","gaps":["The structural basis of the KCTD3–HCN3 C-terminus interaction has not been resolved","The trafficking mechanism by which KCTD3 tetramerization promotes HCN3 surface delivery is unknown","In vivo physiological consequences of KCTD3-mediated HCN3 regulation have not been tested in animal models"]},{"year":2018,"claim":"The question of KCTD3's relevance to human disease was resolved when biallelic loss-of-function mutations were shown to cause developmental epileptic encephalopathy with cerebellar abnormalities across multiple families, establishing KCTD3 as essential for normal brain development.","evidence":"Whole exome sequencing with segregation analysis in four consanguineous families (7 affected individuals)","pmids":["29406573"],"confidence":"Medium","gaps":["No functional rescue or model organism knockout has confirmed causality","Whether the disease mechanism involves loss of HCN3 regulation, other KCTD3 functions, or both is unknown","The specific contribution of KCTD3 to cerebellar development has not been dissected"]},{"year":null,"claim":"It remains unknown how KCTD3 tetramerization mechanistically promotes HCN3 surface trafficking, whether KCTD3 has HCN3-independent functions in brain or kidney, and whether the epileptic encephalopathy phenotype is directly attributable to impaired HCN3 regulation.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of the KCTD3–HCN3 complex exists","KCTD3 function in kidney, where it is highly expressed, is uncharacterized","No animal model with KCTD3 loss-of-function has been reported"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0]}],"pathway":[{"term_id":"GO:0005215","term_label":"transporter activity","supporting_discovery_ids":[0]}],"complexes":[],"partners":["HCN3"],"other_free_text":[]},"mechanistic_narrative":"KCTD3 is an accessory subunit of the HCN3 ion channel that binds specifically to the HCN3 C-terminus via its own C-terminal half and up-regulates HCN3 cell surface expression and current density, requiring its N-terminal tetramerization domain for this functional effect [PMID:23382386]. Domain-swap experiments demonstrate that the HCN3 cytosolic C-terminus is the critical determinant of KCTD3 sensitivity, as replacing the HCN2 C-terminus with that of HCN3 confers KCTD3-mediated current augmentation [PMID:23382386]. Biallelic loss-of-function mutations in KCTD3 cause developmental epileptic encephalopathy with cerebellar abnormalities, global developmental delay, and hypotonia [PMID:29406573]."},"prefetch_data":{"uniprot":{"accession":"Q9Y597","full_name":"BTB/POZ domain-containing protein KCTD3","aliases":["Renal carcinoma antigen NY-REN-45"],"length_aa":815,"mass_kda":89.0,"function":"Accessory subunit of potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) up-regulating its cell-surface expression and current density without affecting its voltage dependence and kinetics","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/Q9Y597/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/KCTD3","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"SNX27","stoichiometry":4.0}],"url":"https://opencell.sf.czbiohub.org/search/KCTD3","total_profiled":1310},"omim":[{"mim_id":"613272","title":"POTASSIUM CHANNEL TETRAMERIZATION DOMAIN-CONTAINING PROTEIN 3; KCTD3","url":"https://www.omim.org/entry/613272"},{"mim_id":"612100","title":"AUTISM, SUSCEPTIBILITY TO, 15; AUTS15","url":"https://www.omim.org/entry/612100"},{"mim_id":"609973","title":"HYPERPOLARIZATION-ACTIVATED CYCLIC NUCLEOTIDE-GATED POTASSIUM CHANNEL 3; HCN3","url":"https://www.omim.org/entry/609973"},{"mim_id":"604569","title":"CONTACTIN-ASSOCIATED PROTEIN-LIKE 2; CNTNAP2","url":"https://www.omim.org/entry/604569"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/KCTD3"},"hgnc":{"alias_symbol":["NY-REN-45"],"prev_symbol":[]},"alphafold":{"accession":"Q9Y597","domains":[{"cath_id":"3.30.710.10","chopping":"18-115","consensus_level":"high","plddt":90.2321,"start":18,"end":115}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y597","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y597-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9Y597-F1-predicted_aligned_error_v6.png","plddt_mean":70.31},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=KCTD3","jax_strain_url":"https://www.jax.org/strain/search?query=KCTD3"},"sequence":{"accession":"Q9Y597","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9Y597.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9Y597/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9Y597"}},"corpus_meta":[{"pmid":"25558065","id":"PMC_25558065","title":"Accelerating novel candidate gene discovery in neurogenetic disorders via whole-exome sequencing of prescreened multiplex consanguineous families.","date":"2014","source":"Cell reports","url":"https://pubmed.ncbi.nlm.nih.gov/25558065","citation_count":378,"is_preprint":false},{"pmid":"31197948","id":"PMC_31197948","title":"KCTD: A new gene family involved in neurodevelopmental and neuropsychiatric disorders.","date":"2019","source":"CNS neuroscience & therapeutics","url":"https://pubmed.ncbi.nlm.nih.gov/31197948","citation_count":100,"is_preprint":false},{"pmid":"19582487","id":"PMC_19582487","title":"Disruption of CNTNAP2 and additional structural genome changes in a boy with speech delay and autism spectrum disorder.","date":"2009","source":"Neurogenetics","url":"https://pubmed.ncbi.nlm.nih.gov/19582487","citation_count":100,"is_preprint":false},{"pmid":"11152963","id":"PMC_11152963","title":"SETA is a multifunctional adapter protein with three SH3 domains that binds Grb2, Cbl, and the novel SB1 proteins.","date":"2000","source":"Cellular signalling","url":"https://pubmed.ncbi.nlm.nih.gov/11152963","citation_count":56,"is_preprint":false},{"pmid":"32952011","id":"PMC_32952011","title":"Using imputed whole-genome sequence variants to uncover candidate mutations and genes affecting milking speed and temperament in Holstein cattle.","date":"2020","source":"Journal of dairy science","url":"https://pubmed.ncbi.nlm.nih.gov/32952011","citation_count":29,"is_preprint":false},{"pmid":"23382386","id":"PMC_23382386","title":"Up-regulation of hyperpolarization-activated cyclic nucleotide-gated channel 3 (HCN3) by specific interaction with K+ channel tetramerization domain-containing protein 3 (KCTD3).","date":"2013","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/23382386","citation_count":20,"is_preprint":false},{"pmid":"29406573","id":"PMC_29406573","title":"Phenotypic characterization of KCTD3-related developmental epileptic encephalopathy.","date":"2018","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/29406573","citation_count":18,"is_preprint":false},{"pmid":"28075205","id":"PMC_28075205","title":"A Genomic and Protein-Protein Interaction Analyses of Nonsyndromic Hearing Impairment in Cameroon Using Targeted Genomic Enrichment and Massively Parallel Sequencing.","date":"2017","source":"Omics : a journal of integrative biology","url":"https://pubmed.ncbi.nlm.nih.gov/28075205","citation_count":13,"is_preprint":false},{"pmid":"37469193","id":"PMC_37469193","title":"DNA methylation at birth and lateral ventricular volume in childhood: a neuroimaging epigenetics study.","date":"2023","source":"Journal of child psychology and psychiatry, and allied disciplines","url":"https://pubmed.ncbi.nlm.nih.gov/37469193","citation_count":6,"is_preprint":false},{"pmid":"40290421","id":"PMC_40290421","title":"Genetic aetiologies in relation to response to the ketogenic diet in 226 children with epilepsy.","date":"2025","source":"Brain communications","url":"https://pubmed.ncbi.nlm.nih.gov/40290421","citation_count":4,"is_preprint":false},{"pmid":"25353171","id":"PMC_25353171","title":"Genetic analysis of intracapillary glomerular lipoprotein deposits in aging mice.","date":"2014","source":"PloS one","url":"https://pubmed.ncbi.nlm.nih.gov/25353171","citation_count":3,"is_preprint":false},{"pmid":"37550298","id":"PMC_37550298","title":"Biallelic KCTD3 nonsense variant derived from paternal uniparental isodisomy of chromosome 1 in a patient with developmental epileptic encephalopathy and distinctive features.","date":"2023","source":"Human genome variation","url":"https://pubmed.ncbi.nlm.nih.gov/37550298","citation_count":1,"is_preprint":false},{"pmid":"41158273","id":"PMC_41158273","title":"Establishment and characterization of two patient-derived cell lines from a patient with gallbladder carcinoma.","date":"2025","source":"Translational cancer research","url":"https://pubmed.ncbi.nlm.nih.gov/41158273","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":8571,"output_tokens":903,"usd":0.019629},"stage2":{"model":"claude-opus-4-6","input_tokens":4087,"output_tokens":2561,"usd":0.12669},"total_usd":0.146319,"stage1_batch_id":"msgbatch_01Mgbec4vM6c9vXht7JVJzss","stage2_batch_id":"msgbatch_01JkuuH5RB2BdJNsgnhjbC6s","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2013,\n      \"finding\": \"KCTD3 specifically binds to the C-terminus of HCN3 (but not other HCN family members) and functions as an accessory subunit that profoundly up-regulates cell surface expression and current density of HCN3. The C-terminal half of KCTD3 is sufficient for binding, but the complete protein including the N-terminal tetramerization domain is required for HCN3 current up-regulation. Replacement of the cytosolic C-terminus of HCN2 with the HCN3 C-terminus confers KCTD3 sensitivity, demonstrating the HCN3 C-terminus is the critical interaction domain.\",\n      \"method\": \"Co-immunoprecipitation, heterologous expression, electrophysiology, domain-swap mutagenesis, immunohistochemistry/colocalization in brain\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1–2 — multiple orthogonal methods (Co-IP, electrophysiology, mutagenesis, domain swaps) in a single rigorous study establishing mechanism\",\n      \"pmids\": [\"23382386\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"SETA (an alias/related protein context; relevant insofar as KCTD3/SB1 is identified as a binding partner): A novel gene SB1 (SETA binding protein 1), identified as sharing 55% amino acid identity with the renal tumor antigen NY-REN-45, was found to bind SETA via its SH3 domain, confirmed by in vitro confrontation and co-immunoprecipitation.\",\n      \"method\": \"Yeast two-hybrid screening, in vitro binding assay, co-immunoprecipitation\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 — SB1/NY-REN-45 identity to KCTD3 is not explicitly confirmed; the paper does not directly characterize KCTD3 function, only identifies it as a binding partner of SETA\",\n      \"pmids\": [\"11152963\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Biallelic loss-of-function mutations in KCTD3 cause a consistent phenotype of developmental epileptic encephalopathy, global developmental delay, hypotonia, and posterior fossa/cerebellar abnormalities, establishing KCTD3 as required for normal brain and cerebellar development.\",\n      \"method\": \"Whole exome sequencing with segregation analysis in four consanguineous families (7 affected individuals)\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — clean loss-of-function human genetics with defined phenotypic readout, replicated across multiple families; no in vitro mechanism\",\n      \"pmids\": [\"29406573\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"KCTD3 functions as an accessory subunit of the HCN3 ion channel, binding specifically to the HCN3 C-terminus via its own C-terminal half and requiring its N-terminal tetramerization domain to up-regulate HCN3 cell surface expression and current density; biallelic loss-of-function mutations in humans cause developmental epileptic encephalopathy with cerebellar abnormalities, consistent with its high expression in brain and kidney.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"KCTD3 is an accessory subunit of the HCN3 ion channel that binds specifically to the HCN3 C-terminus via its own C-terminal half and up-regulates HCN3 cell surface expression and current density, requiring its N-terminal tetramerization domain for this functional effect [PMID:23382386]. Domain-swap experiments demonstrate that the HCN3 cytosolic C-terminus is the critical determinant of KCTD3 sensitivity, as replacing the HCN2 C-terminus with that of HCN3 confers KCTD3-mediated current augmentation [PMID:23382386]. Biallelic loss-of-function mutations in KCTD3 cause developmental epileptic encephalopathy with cerebellar abnormalities, global developmental delay, and hypotonia [PMID:29406573].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Before KCTD3's molecular function was known, a yeast two-hybrid screen identified a protein (SB1/NY-REN-45, sharing identity with KCTD3) as an SH3-domain binding partner of the adaptor protein SETA, suggesting KCTD3 participates in protein–protein interactions but leaving its physiological role unresolved.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, and co-immunoprecipitation with SETA\",\n      \"pmids\": [\"11152963\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"The identity of SB1/NY-REN-45 with KCTD3 is not explicitly confirmed in this study\",\n        \"No functional consequence of the SETA–SB1 interaction was demonstrated\",\n        \"No independent validation of this interaction has been reported\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The key mechanistic question — what ion channel or signaling pathway KCTD3 regulates — was answered by demonstrating that KCTD3 is a specific accessory subunit of HCN3, binding its C-terminus and profoundly enhancing its surface expression and current density through a mechanism requiring KCTD3 tetramerization.\",\n      \"evidence\": \"Co-immunoprecipitation, heterologous expression electrophysiology, domain-swap mutagenesis, and brain colocalization immunohistochemistry\",\n      \"pmids\": [\"23382386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The structural basis of the KCTD3–HCN3 C-terminus interaction has not been resolved\",\n        \"The trafficking mechanism by which KCTD3 tetramerization promotes HCN3 surface delivery is unknown\",\n        \"In vivo physiological consequences of KCTD3-mediated HCN3 regulation have not been tested in animal models\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The question of KCTD3's relevance to human disease was resolved when biallelic loss-of-function mutations were shown to cause developmental epileptic encephalopathy with cerebellar abnormalities across multiple families, establishing KCTD3 as essential for normal brain development.\",\n      \"evidence\": \"Whole exome sequencing with segregation analysis in four consanguineous families (7 affected individuals)\",\n      \"pmids\": [\"29406573\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional rescue or model organism knockout has confirmed causality\",\n        \"Whether the disease mechanism involves loss of HCN3 regulation, other KCTD3 functions, or both is unknown\",\n        \"The specific contribution of KCTD3 to cerebellar development has not been dissected\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how KCTD3 tetramerization mechanistically promotes HCN3 surface trafficking, whether KCTD3 has HCN3-independent functions in brain or kidney, and whether the epileptic encephalopathy phenotype is directly attributable to impaired HCN3 regulation.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of the KCTD3–HCN3 complex exists\",\n        \"KCTD3 function in kidney, where it is highly expressed, is uncharacterized\",\n        \"No animal model with KCTD3 loss-of-function has been reported\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"GO:0005215\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HCN3\"],\n    \"other_free_text\": []\n  }\n}\n```\n\nWait, I made an error — the pathway slot should use Reactome IDs, not GO IDs. Let me fix that.\n\n```json\n{\n  \"mechanistic_narrative\": \"KCTD3 is an accessory subunit of the HCN3 ion channel that binds specifically to the HCN3 C-terminus via its own C-terminal half and up-regulates HCN3 cell surface expression and current density, requiring its N-terminal tetramerization domain for this functional effect [PMID:23382386]. Domain-swap experiments demonstrate that the HCN3 cytosolic C-terminus is the critical determinant of KCTD3 sensitivity, as replacing the HCN2 C-terminus with that of HCN3 confers KCTD3-mediated current augmentation [PMID:23382386]. Biallelic loss-of-function mutations in KCTD3 cause developmental epileptic encephalopathy with cerebellar abnormalities, global developmental delay, and hypotonia [PMID:29406573].\",\n  \"teleology\": [\n    {\n      \"year\": 2000,\n      \"claim\": \"Before KCTD3's molecular function was known, a yeast two-hybrid screen identified a protein (SB1/NY-REN-45, sharing identity with KCTD3) as an SH3-domain binding partner of the adaptor protein SETA, suggesting KCTD3 participates in protein–protein interactions but leaving its physiological role unresolved.\",\n      \"evidence\": \"Yeast two-hybrid, in vitro binding, and co-immunoprecipitation with SETA\",\n      \"pmids\": [\"11152963\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"The identity of SB1/NY-REN-45 with KCTD3 is not explicitly confirmed in this study\",\n        \"No functional consequence of the SETA–SB1 interaction was demonstrated\",\n        \"No independent validation of this interaction has been reported\"\n      ]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"The key mechanistic question — what ion channel or signaling pathway KCTD3 regulates — was answered by demonstrating that KCTD3 is a specific accessory subunit of HCN3, binding its C-terminus and profoundly enhancing its surface expression and current density through a mechanism requiring KCTD3 tetramerization.\",\n      \"evidence\": \"Co-immunoprecipitation, heterologous expression electrophysiology, domain-swap mutagenesis, and brain colocalization immunohistochemistry\",\n      \"pmids\": [\"23382386\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\n        \"The structural basis of the KCTD3–HCN3 C-terminus interaction has not been resolved\",\n        \"The trafficking mechanism by which KCTD3 tetramerization promotes HCN3 surface delivery is unknown\",\n        \"In vivo physiological consequences of KCTD3-mediated HCN3 regulation have not been tested in animal models\"\n      ]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"The question of KCTD3's relevance to human disease was resolved when biallelic loss-of-function mutations were shown to cause developmental epileptic encephalopathy with cerebellar abnormalities across multiple families, establishing KCTD3 as essential for normal brain development.\",\n      \"evidence\": \"Whole exome sequencing with segregation analysis in four consanguineous families (7 affected individuals)\",\n      \"pmids\": [\"29406573\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\n        \"No functional rescue or model organism knockout has confirmed causality\",\n        \"Whether the disease mechanism involves loss of HCN3 regulation, other KCTD3 functions, or both is unknown\",\n        \"The specific contribution of KCTD3 to cerebellar development has not been dissected\"\n      ]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"It remains unknown how KCTD3 tetramerization mechanistically promotes HCN3 surface trafficking, whether KCTD3 has HCN3-independent functions in brain or kidney, and whether the epileptic encephalopathy phenotype is directly attributable to impaired HCN3 regulation.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\n        \"No structural model of the KCTD3–HCN3 complex exists\",\n        \"KCTD3 function in kidney, where it is highly expressed, is uncharacterized\",\n        \"No animal model with KCTD3 loss-of-function has been reported\"\n      ]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-382551\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"HCN3\"],\n    \"other_free_text\": []\n  }\n}\n```"}