{"gene":"CFAP251","run_date":"2026-06-09T22:57:18","timeline":{"discoveries":[{"year":2018,"finding":"WDR66/CFAP251 encodes an axonemal protein that localizes to the calmodulin- and spoke-associated complex at the base of radial spoke 3 of the axoneme. Deletion of the C-terminal region (mimicking the human deletion) in the Trypanosoma ortholog TbWDR66 impaired flagellar movement, confirming the functional importance of the WDR66 C-terminal region for flagellar motility.","method":"Whole-exome sequencing for variant identification; Trypanosoma ortholog (TbWDR66) deletion model with flagellar movement assay; sequence and structural analogy analysis; axonemal localization confirmed in model organism","journal":"American journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional validation in Trypanosoma model with motility readout, plus human deletion genetics; single lab but two orthogonal approaches (genetics + model organism functional assay)","pmids":["30122540"],"is_preprint":false},{"year":2018,"finding":"CFAP251 is a component of the calmodulin- and radial-spoke-associated complex, located adjacent to DNAH1 on the inner surface of peripheral microtubule doublets of the axoneme. Loss-of-function mutations in WDR66 abolish CFAP251 protein along the flagellum and cause failure of mitochondrial sheath formation during spermatozoon biogenesis. A spermatozoa-specific CFAP251 isoform was identified, likely generated during spermatozoon maturation. In Tetrahymena, the CFAP251 ortholog is necessary for efficient coordinated ciliary beating.","method":"Whole-exome and Sanger sequencing; immunofluorescence showing absence of CFAP251 in mutant sperm; transmission electron microscopy of sperm ultrastructure; Tetrahymena ortholog functional studies","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal localization by immunofluorescence, ultrastructural TEM with defined mitochondrial sheath phenotype, and Tetrahymena functional validation; replicated in same publication with multiple orthogonal methods","pmids":["30122541"],"is_preprint":false},{"year":2018,"finding":"Biallelic loss-of-function mutations in CFAP251 cause absence/reduction of CFAP251 protein in sperm flagella, as demonstrated by immunofluorescence in a CFAP251-deficient man, confirming involvement of CFAP251 in flagellar development and male infertility.","method":"Whole-exome sequencing; gene expression assays; immunofluorescence staining in CFAP251-deficient patient sperm","journal":"Journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — immunofluorescence localization in patient material corroborating prior findings; single lab, consistent with replicated data from other groups","pmids":["30310178"],"is_preprint":false},{"year":2022,"finding":"A novel splicing mutation in CFAP251 (c.1192-3C>G) causes exon skipping, leading to significantly reduced CFAP251 protein expression in spermatozoa, confirming that the C-terminal coding region is required for protein stability/production and that loss of CFAP251 protein causes MMAF.","method":"Whole-exome sequencing; RT-PCR demonstrating exon skipping; western blotting and immunofluorescence of patient spermatozoa","journal":"Frontiers in genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct molecular validation of splicing consequence by RT-PCR and protein loss by western blot/IF in patient material; single lab, single case","pmids":["35087568"],"is_preprint":false},{"year":2026,"finding":"CFAP251 physically interacts with beta-tubulin TUBB4B; its loss disrupts TUBB4B recruitment/stability, impairing spermiogenesis and ciliary function. CFAP251 also interacts with mitochondrial protein SLC25A4, suggesting a role in energy transport. A Cfap251 knockout mouse recapitulates human MMAF and male infertility, and additionally shows PCD-like ciliary defects including airway symptoms.","method":"Cfap251 knockout mouse model (C57Bl/6J); whole-exome sequencing of human probands; co-immunoprecipitation or interaction assay identifying TUBB4B and SLC25A4 as binding partners; immunofluorescence/western blot showing TUBB4B downregulation","journal":"International journal of biological sciences","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — knockout mouse model with defined cellular phenotype plus identified protein-protein interactions (TUBB4B, SLC25A4) in a single recent study; abstract does not specify Co-IP vs pulldown methodology so tier capped at 2","pmids":["41943837"],"is_preprint":false}],"current_model":"CFAP251 (WDR66) is an axonemal protein residing in the calmodulin- and radial-spoke-associated complex adjacent to DNAH1 at the inner surface of peripheral microtubule doublets; it physically interacts with TUBB4B (whose stability depends on CFAP251) and with mitochondrial carrier SLC25A4, and its loss—caused by biallelic loss-of-function mutations—disrupts flagellar axoneme organization, mitochondrial sheath formation, and ciliary beating, resulting in multiple morphological abnormalities of the sperm flagellum (MMAF) and male infertility, with PCD-like ciliary defects also observed in knockout mice."},"narrative":{"mechanistic_narrative":"CFAP251 (WDR66) is an axonemal protein required for the structural organization and motility of cilia and sperm flagella [PMID:30122540, PMID:30122541]. It localizes to the calmodulin- and radial-spoke-associated complex at the base of radial spoke 3, residing adjacent to DNAH1 on the inner surface of peripheral microtubule doublets [PMID:30122540, PMID:30122541]. CFAP251 physically interacts with beta-tubulin TUBB4B, whose recruitment and stability depend on CFAP251, and with the mitochondrial carrier SLC25A4, linking the protein to axonemal microtubule architecture and to flagellar energy supply [PMID:41943837]. Loss of CFAP251 abolishes the protein along the flagellum, disrupts mitochondrial sheath formation during spermatozoon biogenesis, and impairs coordinated ciliary beating [PMID:30122541]. Biallelic loss-of-function mutations in CFAP251 cause multiple morphological abnormalities of the sperm flagellum (MMAF) and male infertility, and a knockout mouse additionally displays primary ciliary dyskinesia-like airway defects [PMID:30310178, PMID:35087568, PMID:41943837].","teleology":[{"year":2018,"claim":"Established that WDR66/CFAP251 is an axonemal protein localizing to the calmodulin- and spoke-associated complex and that its C-terminal region is functionally required for flagellar motility, answering whether the gene contributes directly to ciliary/flagellar movement.","evidence":"Whole-exome sequencing plus Trypanosoma TbWDR66 C-terminal deletion model with flagellar movement assay and axonemal localization","pmids":["30122540"],"confidence":"Medium","gaps":["Mechanism by which the C-terminal region supports motility not defined","Direct molecular partners within the axoneme not identified","Functional validation relies on a trypanosome ortholog"]},{"year":2018,"claim":"Defined the precise axonemal position of CFAP251 (base of radial spoke 3, adjacent to DNAH1) and connected its loss to failure of mitochondrial sheath formation, establishing both a structural locale and a developmental consequence in spermatogenesis.","evidence":"Whole-exome/Sanger sequencing, immunofluorescence of mutant sperm, TEM ultrastructure, and Tetrahymena ortholog functional studies","pmids":["30122541"],"confidence":"High","gaps":["Molecular basis of mitochondrial sheath defect not resolved","Function of the sperm-specific isoform not characterized","Direct binding partners not yet identified"]},{"year":2018,"claim":"Corroborated in independent patient material that biallelic loss-of-function mutations abolish CFAP251 protein in sperm flagella and cause male infertility, strengthening the gene-disease link.","evidence":"Whole-exome sequencing, expression assays, and immunofluorescence in a CFAP251-deficient man","pmids":["30310178"],"confidence":"Medium","gaps":["Single patient","Does not add mechanistic detail beyond protein loss"]},{"year":2022,"claim":"Demonstrated that a splicing mutation causing exon skipping reduces CFAP251 protein in spermatozoa, confirming that loss of CFAP251 protein is the direct cause of MMAF.","evidence":"Whole-exome sequencing, RT-PCR for exon skipping, western blot and immunofluorescence of patient spermatozoa","pmids":["35087568"],"confidence":"Medium","gaps":["Single case","No reconstitution of protein function"]},{"year":2026,"claim":"Identified direct physical partners of CFAP251 (TUBB4B and SLC25A4) and showed via a knockout mouse that CFAP251 loss destabilizes TUBB4B and produces both MMAF and PCD-like ciliary defects, linking the protein to microtubule stability and flagellar energy transport.","evidence":"Cfap251 knockout mouse, human proband exome sequencing, interaction assay, and immunofluorescence/western blot showing TUBB4B downregulation","pmids":["41943837"],"confidence":"Medium","gaps":["Co-IP versus pulldown methodology not specified","Mechanism by which SLC25A4 interaction supports energy transport not established","Stoichiometry and direct versus indirect nature of interactions unconfirmed"]},{"year":null,"claim":"How CFAP251 organizes the calmodulin- and radial-spoke-associated complex at a structural level and how its loss mechanistically links axonemal disruption to mitochondrial sheath failure remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of the CFAP251 complex","Mechanism connecting axonemal role to mitochondrial sheath formation unknown","Function of the sperm-specific isoform uncharacterized"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[4]}],"localization":[],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[1,2,3]}],"complexes":["calmodulin- and radial-spoke-associated complex"],"partners":["TUBB4B","SLC25A4","DNAH1"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q8TBY9","full_name":"Cilia- and flagella-associated protein 251","aliases":["WD repeat-containing protein 66"],"length_aa":1149,"mass_kda":130.0,"function":"Involved in spermatozoa motility (PubMed:30122540, PubMed:30122541). May also regulate cilium motility through its role in the assembly of the axonemal radial spokes (By similarity)","subcellular_location":"Cytoplasm, cytoskeleton, cilium axoneme; Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/Q8TBY9/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/CFAP251","classification":"Not Classified","n_dependent_lines":2,"n_total_lines":1208,"dependency_fraction":0.0016556291390728477},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/CFAP251","total_profiled":1310},"omim":[{"mim_id":"621376","title":"CILIA- AND FLAGELLA-ASSOCIATED PROTEIN 206; CFAP206","url":"https://www.omim.org/entry/621376"},{"mim_id":"620381","title":"CILIA- AND FLAGELLA-ASSOCIATED PROTEIN 61; CFAP61","url":"https://www.omim.org/entry/620381"},{"mim_id":"618152","title":"SPERMATOGENIC FAILURE 33; SPGF33","url":"https://www.omim.org/entry/618152"},{"mim_id":"618146","title":"CILIA- AND FLAGELLA-ASSOCIATED PROTEIN 251; CFAP251","url":"https://www.omim.org/entry/618146"},{"mim_id":"609910","title":"CILIA- AND FLAGELLA-ASSOCIATED PROTEIN 91; CFAP91","url":"https://www.omim.org/entry/609910"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Mid piece","reliability":"Supported"},{"location":"End piece","reliability":"Supported"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"choroid plexus","ntpm":19.0},{"tissue":"fallopian tube","ntpm":20.9},{"tissue":"testis","ntpm":18.6}],"url":"https://www.proteinatlas.org/search/CFAP251"},"hgnc":{"alias_symbol":["MGC33630","CaM-IP4"],"prev_symbol":["WDR66"]},"alphafold":{"accession":"Q8TBY9","domains":[{"cath_id":"2.130.10.10","chopping":"801-934","consensus_level":"medium","plddt":91.3002,"start":801,"end":934},{"cath_id":"1.10.238.10","chopping":"941-1038","consensus_level":"high","plddt":87.23,"start":941,"end":1038},{"cath_id":"-","chopping":"1046-1136","consensus_level":"high","plddt":77.7204,"start":1046,"end":1136}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBY9","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBY9-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q8TBY9-F1-predicted_aligned_error_v6.png","plddt_mean":76.62},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=CFAP251","jax_strain_url":"https://www.jax.org/strain/search?query=CFAP251"},"sequence":{"accession":"Q8TBY9","fasta_url":"https://rest.uniprot.org/uniprotkb/Q8TBY9.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q8TBY9/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q8TBY9"}},"corpus_meta":[{"pmid":"30122540","id":"PMC_30122540","title":"A Homozygous Ancestral SVA-Insertion-Mediated Deletion in WDR66 Induces Multiple Morphological Abnormalities of the Sperm Flagellum and Male Infertility.","date":"2018","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30122540","citation_count":76,"is_preprint":false},{"pmid":"23514407","id":"PMC_23514407","title":"Wdr66 is a novel marker for risk stratification and involved in epithelial-mesenchymal transition of esophageal squamous cell carcinoma.","date":"2013","source":"BMC cancer","url":"https://pubmed.ncbi.nlm.nih.gov/23514407","citation_count":75,"is_preprint":false},{"pmid":"30122541","id":"PMC_30122541","title":"Loss of Calmodulin- and Radial-Spoke-Associated Complex Protein CFAP251 Leads to Immotile Spermatozoa Lacking Mitochondria and Infertility in Men.","date":"2018","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30122541","citation_count":74,"is_preprint":false},{"pmid":"30310178","id":"PMC_30310178","title":"Biallelic mutations of CFAP251 cause sperm flagellar defects and human male infertility.","date":"2018","source":"Journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/30310178","citation_count":60,"is_preprint":false},{"pmid":"31225659","id":"PMC_31225659","title":"LINC00324 accelerates the proliferation and migration of osteosarcoma through regulating WDR66.","date":"2019","source":"Journal of cellular physiology","url":"https://pubmed.ncbi.nlm.nih.gov/31225659","citation_count":33,"is_preprint":false},{"pmid":"31140103","id":"PMC_31140103","title":"LIN28A-stabilized FBXL19-AS1 promotes breast cancer migration, invasion and EMT by regulating WDR66.","date":"2019","source":"In vitro cellular & developmental biology. Animal","url":"https://pubmed.ncbi.nlm.nih.gov/31140103","citation_count":21,"is_preprint":false},{"pmid":"29717028","id":"PMC_29717028","title":"Long non-coding RNA AK096174 promotes cell proliferation and invasion in gastric cancer by regulating WDR66 expression.","date":"2018","source":"Bioscience reports","url":"https://pubmed.ncbi.nlm.nih.gov/29717028","citation_count":14,"is_preprint":false},{"pmid":"35087568","id":"PMC_35087568","title":"Successful Results of Intracytoplasmic Sperm Injection of a Chinese Patient With Multiple Morphological Abnormalities of Sperm Flagella Caused by a Novel Splicing Mutation in CFAP251.","date":"2022","source":"Frontiers in genetics","url":"https://pubmed.ncbi.nlm.nih.gov/35087568","citation_count":13,"is_preprint":false},{"pmid":"38230259","id":"PMC_38230259","title":"CircPOFUT1 fosters colorectal cancer metastasis and chemoresistance via decoying miR-653-5p/E2F7/WDR66 axis and stabilizing BMI1.","date":"2023","source":"iScience","url":"https://pubmed.ncbi.nlm.nih.gov/38230259","citation_count":8,"is_preprint":false},{"pmid":"41943837","id":"PMC_41943837","title":"CFAP251 Deficiency Induces Male Infertility and PCD-like Ciliary Defects by Disrupting TUBB4B and SLC25A4 Recruitment in Humans and Mice.","date":"2026","source":"International journal of biological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/41943837","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":7485,"output_tokens":1579,"usd":0.02307,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8322,"output_tokens":2070,"usd":0.04668,"stage2_stop_reason":"end_turn"},"total_usd":0.06975,"stage1_batch_id":"msgbatch_01ACAxJQabDsht39JXeWG22d","stage2_batch_id":"msgbatch_01QEU22A9U5sbPTgsMzTmvSf","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2018,\n      \"finding\": \"WDR66/CFAP251 encodes an axonemal protein that localizes to the calmodulin- and spoke-associated complex at the base of radial spoke 3 of the axoneme. Deletion of the C-terminal region (mimicking the human deletion) in the Trypanosoma ortholog TbWDR66 impaired flagellar movement, confirming the functional importance of the WDR66 C-terminal region for flagellar motility.\",\n      \"method\": \"Whole-exome sequencing for variant identification; Trypanosoma ortholog (TbWDR66) deletion model with flagellar movement assay; sequence and structural analogy analysis; axonemal localization confirmed in model organism\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional validation in Trypanosoma model with motility readout, plus human deletion genetics; single lab but two orthogonal approaches (genetics + model organism functional assay)\",\n      \"pmids\": [\"30122540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"CFAP251 is a component of the calmodulin- and radial-spoke-associated complex, located adjacent to DNAH1 on the inner surface of peripheral microtubule doublets of the axoneme. Loss-of-function mutations in WDR66 abolish CFAP251 protein along the flagellum and cause failure of mitochondrial sheath formation during spermatozoon biogenesis. A spermatozoa-specific CFAP251 isoform was identified, likely generated during spermatozoon maturation. In Tetrahymena, the CFAP251 ortholog is necessary for efficient coordinated ciliary beating.\",\n      \"method\": \"Whole-exome and Sanger sequencing; immunofluorescence showing absence of CFAP251 in mutant sperm; transmission electron microscopy of sperm ultrastructure; Tetrahymena ortholog functional studies\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal localization by immunofluorescence, ultrastructural TEM with defined mitochondrial sheath phenotype, and Tetrahymena functional validation; replicated in same publication with multiple orthogonal methods\",\n      \"pmids\": [\"30122541\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Biallelic loss-of-function mutations in CFAP251 cause absence/reduction of CFAP251 protein in sperm flagella, as demonstrated by immunofluorescence in a CFAP251-deficient man, confirming involvement of CFAP251 in flagellar development and male infertility.\",\n      \"method\": \"Whole-exome sequencing; gene expression assays; immunofluorescence staining in CFAP251-deficient patient sperm\",\n      \"journal\": \"Journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — immunofluorescence localization in patient material corroborating prior findings; single lab, consistent with replicated data from other groups\",\n      \"pmids\": [\"30310178\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A novel splicing mutation in CFAP251 (c.1192-3C>G) causes exon skipping, leading to significantly reduced CFAP251 protein expression in spermatozoa, confirming that the C-terminal coding region is required for protein stability/production and that loss of CFAP251 protein causes MMAF.\",\n      \"method\": \"Whole-exome sequencing; RT-PCR demonstrating exon skipping; western blotting and immunofluorescence of patient spermatozoa\",\n      \"journal\": \"Frontiers in genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct molecular validation of splicing consequence by RT-PCR and protein loss by western blot/IF in patient material; single lab, single case\",\n      \"pmids\": [\"35087568\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"CFAP251 physically interacts with beta-tubulin TUBB4B; its loss disrupts TUBB4B recruitment/stability, impairing spermiogenesis and ciliary function. CFAP251 also interacts with mitochondrial protein SLC25A4, suggesting a role in energy transport. A Cfap251 knockout mouse recapitulates human MMAF and male infertility, and additionally shows PCD-like ciliary defects including airway symptoms.\",\n      \"method\": \"Cfap251 knockout mouse model (C57Bl/6J); whole-exome sequencing of human probands; co-immunoprecipitation or interaction assay identifying TUBB4B and SLC25A4 as binding partners; immunofluorescence/western blot showing TUBB4B downregulation\",\n      \"journal\": \"International journal of biological sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — knockout mouse model with defined cellular phenotype plus identified protein-protein interactions (TUBB4B, SLC25A4) in a single recent study; abstract does not specify Co-IP vs pulldown methodology so tier capped at 2\",\n      \"pmids\": [\"41943837\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"CFAP251 (WDR66) is an axonemal protein residing in the calmodulin- and radial-spoke-associated complex adjacent to DNAH1 at the inner surface of peripheral microtubule doublets; it physically interacts with TUBB4B (whose stability depends on CFAP251) and with mitochondrial carrier SLC25A4, and its loss—caused by biallelic loss-of-function mutations—disrupts flagellar axoneme organization, mitochondrial sheath formation, and ciliary beating, resulting in multiple morphological abnormalities of the sperm flagellum (MMAF) and male infertility, with PCD-like ciliary defects also observed in knockout mice.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"CFAP251 (WDR66) is an axonemal protein required for the structural organization and motility of cilia and sperm flagella [#0, #1]. It localizes to the calmodulin- and radial-spoke-associated complex at the base of radial spoke 3, residing adjacent to DNAH1 on the inner surface of peripheral microtubule doublets [#0, #1]. CFAP251 physically interacts with beta-tubulin TUBB4B, whose recruitment and stability depend on CFAP251, and with the mitochondrial carrier SLC25A4, linking the protein to axonemal microtubule architecture and to flagellar energy supply [#4]. Loss of CFAP251 abolishes the protein along the flagellum, disrupts mitochondrial sheath formation during spermatozoon biogenesis, and impairs coordinated ciliary beating [#1]. Biallelic loss-of-function mutations in CFAP251 cause multiple morphological abnormalities of the sperm flagellum (MMAF) and male infertility, and a knockout mouse additionally displays primary ciliary dyskinesia-like airway defects [#2, #3, #4].\",\n  \"teleology\": [\n    {\n      \"year\": 2018,\n      \"claim\": \"Established that WDR66/CFAP251 is an axonemal protein localizing to the calmodulin- and spoke-associated complex and that its C-terminal region is functionally required for flagellar motility, answering whether the gene contributes directly to ciliary/flagellar movement.\",\n      \"evidence\": \"Whole-exome sequencing plus Trypanosoma TbWDR66 C-terminal deletion model with flagellar movement assay and axonemal localization\",\n      \"pmids\": [\"30122540\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanism by which the C-terminal region supports motility not defined\", \"Direct molecular partners within the axoneme not identified\", \"Functional validation relies on a trypanosome ortholog\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined the precise axonemal position of CFAP251 (base of radial spoke 3, adjacent to DNAH1) and connected its loss to failure of mitochondrial sheath formation, establishing both a structural locale and a developmental consequence in spermatogenesis.\",\n      \"evidence\": \"Whole-exome/Sanger sequencing, immunofluorescence of mutant sperm, TEM ultrastructure, and Tetrahymena ortholog functional studies\",\n      \"pmids\": [\"30122541\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of mitochondrial sheath defect not resolved\", \"Function of the sperm-specific isoform not characterized\", \"Direct binding partners not yet identified\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Corroborated in independent patient material that biallelic loss-of-function mutations abolish CFAP251 protein in sperm flagella and cause male infertility, strengthening the gene-disease link.\",\n      \"evidence\": \"Whole-exome sequencing, expression assays, and immunofluorescence in a CFAP251-deficient man\",\n      \"pmids\": [\"30310178\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single patient\", \"Does not add mechanistic detail beyond protein loss\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated that a splicing mutation causing exon skipping reduces CFAP251 protein in spermatozoa, confirming that loss of CFAP251 protein is the direct cause of MMAF.\",\n      \"evidence\": \"Whole-exome sequencing, RT-PCR for exon skipping, western blot and immunofluorescence of patient spermatozoa\",\n      \"pmids\": [\"35087568\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single case\", \"No reconstitution of protein function\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Identified direct physical partners of CFAP251 (TUBB4B and SLC25A4) and showed via a knockout mouse that CFAP251 loss destabilizes TUBB4B and produces both MMAF and PCD-like ciliary defects, linking the protein to microtubule stability and flagellar energy transport.\",\n      \"evidence\": \"Cfap251 knockout mouse, human proband exome sequencing, interaction assay, and immunofluorescence/western blot showing TUBB4B downregulation\",\n      \"pmids\": [\"41943837\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Co-IP versus pulldown methodology not specified\", \"Mechanism by which SLC25A4 interaction supports energy transport not established\", \"Stoichiometry and direct versus indirect nature of interactions unconfirmed\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How CFAP251 organizes the calmodulin- and radial-spoke-associated complex at a structural level and how its loss mechanistically links axonemal disruption to mitochondrial sheath failure remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of the CFAP251 complex\", \"Mechanism connecting axonemal role to mitochondrial sheath formation unknown\", \"Function of the sperm-specific isoform uncharacterized\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005930\", \"supporting_discovery_ids\": [0, 1]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [1, 2, 3]}\n    ],\n    \"complexes\": [\"calmodulin- and radial-spoke-associated complex\"],\n    \"partners\": [\"TUBB4B\", \"SLC25A4\", \"DNAH1\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}