{"gene":"QRICH2","run_date":"2026-06-10T06:43:36","timeline":{"discoveries":[{"year":2019,"finding":"QRICH2 is required for sperm flagellar formation; loss-of-function mutations cause MMAF in humans and Qrich2 knockout male mice show MMAF phenotype and sterility. Proteomic analysis of KO vs wild-type testes revealed that QRICH2 stabilizes and enhances expression of proteins related to flagellar development.","method":"CRISPR-Cas9 knockout mice, proteomic analysis of testes, in vitro experiments","journal":"Nature communications","confidence":"High","confidence_rationale":"Tier 2 / Strong — KO mouse model with defined cellular phenotype, proteomic analysis, and in vitro confirmation; replicated across two independent families","pmids":["30683861"],"is_preprint":false},{"year":2019,"finding":"Homozygous loss-of-function variants in QRICH2 (nonsense mutations c.3501C>G and c.4614C>G) confirmed as causative for MMAF syndrome; heterozygous QRICH2 variants were found at comparable rates in MMAF patients and controls, indicating heterozygous variants alone are not pathogenic for MMAF.","method":"Whole exome sequencing of 167 MMAF-affected subjects, variant analysis","journal":"Clinical genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — large cohort exome sequencing with negative control comparison; single methodology but rigorous cohort design","pmids":["31292949"],"is_preprint":false},{"year":2021,"finding":"QRICH2 physically interacts with AKAP4 (A-kinase anchor protein 4) in sperm; co-localization and co-immunoprecipitation demonstrated their interaction, and a hemizygous loss-of-function AKAP4 variant reduces QRICH2 protein expression in spermatozoa, indicating AKAP4 is required for maintaining QRICH2 expression and that their interaction is necessary for fibrous sheath formation.","method":"Immunofluorescence co-localization, co-immunoprecipitation (Co-IP) in HEK-293T cells, protein expression analysis in patient spermatozoa","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP and immunofluorescence in two systems (cell line + patient sperm), single lab, two orthogonal methods","pmids":["34415320"],"is_preprint":false},{"year":2022,"finding":"A 1-bp deletion causing a frameshift and premature termination codon in bovine QRICH2 leads to low sperm count and immotile sperm with multiple morphological abnormalities of the flagellum; the mutant transcript undergoes nonsense-mediated mRNA decay as shown by testis transcriptome analysis.","method":"Genome sequencing of affected bull, testis transcriptome analysis (nonsense-mediated decay), semen analysis","journal":"Genetics, selection, evolution : GSE","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional variant confirmed in two independent homozygous bulls, transcriptome evidence for NMD, orthogonal semen phenotyping","pmids":["35255804"],"is_preprint":false},{"year":2024,"finding":"QRICH2 acts as a glutamine (Gln) sensor in sperm; Qrich2 KO mice show reduced tubulin glutamylation and microtubule instability in sperm flagella, dysregulated glutamine/glutamate (Gln/Glu) metabolism with accumulated Gln and reduced Glu, and mislocalization of mitochondrial marker proteins in flagella contributing to reduced mitochondrial function and sperm motility. Dietary Gln/Glu deprivation phenocopied Qrich2 KO mice.","method":"Qrich2 KO mouse model, metabolic profiling, tubulin glutamylation assays, mitochondrial localization experiments, dietary intervention rescue experiment","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse model with multiple orthogonal assays and dietary phenocopy experiment; single lab","pmids":["38597976"],"is_preprint":false},{"year":2024,"finding":"QRICH2 has antioxidant properties that protect spermatids from ROS-induced damage; Qrich2 KO mice show elevated ROS levels, DNA damage in spermatids, increased autophagy and apoptosis, and reduced sperm count. Incubation with purified N-terminal QRICH2 protein exhibited antioxidant activity in vitro, enhancing spermatozoa viability and motility.","method":"HE staining, immunofluorescence, flow cytometry, single sperm metabolism analysis in Qrich2 KO mice; in vitro incubation with purified N-terminal QRICH2 protein","journal":"Reproductive biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO mouse phenotyping with multiple assays and in vitro protein function validation; single lab","pmids":["38772286"],"is_preprint":false},{"year":2023,"finding":"CFAP70 regulates sperm flagella biogenesis partially by controlling the expression of QRICH2; Cfap70 KO mice show reduced QRICH2 expression levels, placing CFAP70 upstream of QRICH2 in the flagellar assembly pathway.","method":"Cfap70 KO mouse model, protein expression analysis","journal":"EBioMedicine","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic epistasis via KO mouse model; single lab, single method for the QRICH2-specific finding","pmids":["37352829"],"is_preprint":false},{"year":2026,"finding":"Human QRICH2 has no paralogs, is conserved across mammals with two functional domains, is restricted to the testes at the protein level, localizes to different cellular compartments throughout spermatogenesis, and acts as a cytoskeletal component in mature sperm in both the head and flagellum.","method":"Mass spectrometry isoform identification, in silico paralog/conservation analysis, immunodetection across 12 human organs, proteomic dataset analysis","journal":"Reproduction (Cambridge, England)","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — immunodetection and proteomics across multiple tissues and developmental stages; single lab, multiple methods","pmids":["41575150"],"is_preprint":false}],"current_model":"QRICH2 is a testis-specific cytoskeletal protein essential for sperm flagellar biogenesis that stabilizes flagellar proteins, physically interacts with AKAP4 at the fibrous sheath, regulates tubulin glutamylation and microtubule stability through glutamine/glutamate metabolism sensing, and protects spermatids from ROS-induced damage via antioxidant activity; loss-of-function causes multiple morphological abnormalities of the sperm flagella (MMAF) and male infertility in humans, mice, and cattle, with CFAP70 acting upstream of QRICH2 in the flagellar assembly pathway."},"narrative":{"mechanistic_narrative":"QRICH2 is a testis-restricted cytoskeletal protein essential for sperm flagellar biogenesis, whose loss causes multiple morphological abnormalities of the sperm flagella (MMAF) and male infertility across humans, mice, and cattle [PMID:30683861, PMID:31292949, PMID:35255804]. Mechanistically, QRICH2 stabilizes and sustains the expression of flagellar development proteins [PMID:30683861] and physically interacts with AKAP4 at the fibrous sheath, an interaction required for fibrous sheath formation and for maintaining QRICH2 protein levels in spermatozoa [PMID:34415320]. QRICH2 functions as a glutamine sensor that couples Gln/Glu metabolism to tubulin glutamylation and microtubule stability in the flagellum, with its loss producing dysregulated Gln/Glu balance, mitochondrial protein mislocalization, and impaired motility — a phenotype reproduced by dietary Gln/Glu deprivation [PMID:38597976]. Its N-terminal region carries antioxidant activity that protects spermatids from ROS-induced DNA damage, autophagy, and apoptosis [PMID:38772286]. QRICH2 acts downstream of CFAP70 in the flagellar assembly pathway [PMID:37352829] and localizes to distinct compartments across spermatogenesis, residing in both the head and flagellum of mature sperm [PMID:41575150].","teleology":[{"year":2019,"claim":"Established QRICH2 as a gene required for sperm flagellar formation and defined its molecular role as a stabilizer of flagellar development proteins, linking it directly to human MMAF and infertility.","evidence":"CRISPR-Cas9 knockout mice with MMAF phenotype plus proteomic analysis of testes and human variant identification","pmids":["30683861","31292949"],"confidence":"High","gaps":["Which specific flagellar proteins QRICH2 stabilizes was not resolved at the molecular level","Heterozygous variants alone are not pathogenic, leaving the threshold of QRICH2 dose unclear"]},{"year":2021,"claim":"Identified a direct physical partner, showing QRICH2 interacts with AKAP4 at the fibrous sheath and that this interaction maintains QRICH2 expression — connecting QRICH2 to a defined flagellar structural assembly.","evidence":"Reciprocal Co-IP and immunofluorescence co-localization in HEK-293T cells plus expression analysis in AKAP4-variant patient sperm","pmids":["34415320"],"confidence":"Medium","gaps":["Interaction interface and stoichiometry not mapped","Whether the dependency is mutual or unidirectional not fully resolved"]},{"year":2022,"claim":"Demonstrated cross-species conservation of QRICH2 function by showing a frameshift variant causes MMAF in cattle via nonsense-mediated decay of the transcript.","evidence":"Genome sequencing of affected bulls, testis transcriptome NMD analysis, and semen phenotyping","pmids":["35255804"],"confidence":"Medium","gaps":["Does not add mechanistic detail beyond confirming loss-of-function phenotype"]},{"year":2023,"claim":"Placed QRICH2 within a genetic hierarchy by showing CFAP70 acts upstream, controlling QRICH2 expression during flagellar assembly.","evidence":"Cfap70 knockout mouse model with QRICH2 protein expression analysis","pmids":["37352829"],"confidence":"Medium","gaps":["Whether CFAP70 regulates QRICH2 transcriptionally or post-translationally is unknown","Direct versus indirect regulation not distinguished"]},{"year":2024,"claim":"Defined a metabolic-sensing mechanism: QRICH2 acts as a glutamine sensor linking Gln/Glu metabolism to tubulin glutamylation, microtubule stability, and mitochondrial positioning in the flagellum.","evidence":"Qrich2 KO mouse with metabolic profiling, tubulin glutamylation assays, mitochondrial localization, and dietary Gln/Glu deprivation phenocopy","pmids":["38597976"],"confidence":"Medium","gaps":["Molecular basis of Gln sensing by QRICH2 not structurally defined","Direct enzymatic role in glutamylation versus regulatory role not separated"]},{"year":2024,"claim":"Assigned a cytoprotective function: the QRICH2 N-terminus has intrinsic antioxidant activity protecting spermatids from ROS-induced damage.","evidence":"Qrich2 KO mouse phenotyping for ROS, DNA damage, autophagy and apoptosis plus in vitro incubation with purified N-terminal QRICH2 protein","pmids":["38772286"],"confidence":"Medium","gaps":["Biochemical mechanism of antioxidant activity not characterized","Relationship between antioxidant and cytoskeletal functions not integrated"]},{"year":2026,"claim":"Characterized QRICH2 as a paralog-free, mammal-conserved, testis-restricted protein with two functional domains that relocalizes across spermatogenesis and acts as a cytoskeletal component in both sperm head and flagellum.","evidence":"Mass spectrometry isoform identification, in silico conservation analysis, immunodetection across 12 human organs, and proteomic dataset analysis","pmids":["41575150"],"confidence":"Medium","gaps":["Functional contribution of QRICH2 in the sperm head not defined","Domain-specific activities not mapped to localization changes"]},{"year":null,"claim":"How the metabolic-sensing, antioxidant, and structural functions of QRICH2 are mechanistically integrated, and the molecular basis of its glutamine sensing, remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of QRICH2 domains","No defined enzymatic mechanism for glutamine sensing or antioxidant activity","Direct flagellar protein clients not catalogued"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,7]},{"term_id":"GO:0005198","term_label":"structural molecule activity","supporting_discovery_ids":[7]},{"term_id":"GO:0016209","term_label":"antioxidant activity","supporting_discovery_ids":[5]},{"term_id":"GO:0140299","term_label":"molecular sensor activity","supporting_discovery_ids":[4]}],"localization":[{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[7]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[0,4]}],"pathway":[{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[0,1]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[0,6]}],"complexes":["fibrous sheath"],"partners":["AKAP4","CFAP70"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q9H0J4","full_name":"Glutamine-rich protein 2","aliases":[],"length_aa":1663,"mass_kda":180.8,"function":"Has an essential role in the formation of sperm flagella and flagellar structure maintainance. It acts as a suppressor of ubiquitination and degradation of proteins involved in flagellar development and motility","subcellular_location":"Nucleus membrane; Nucleus; Cytoplasm; Cell projection, cilium, flagellum","url":"https://www.uniprot.org/uniprotkb/Q9H0J4/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/QRICH2","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":[],"url":"https://opencell.sf.czbiohub.org/search/QRICH2","total_profiled":1310},"omim":[{"mim_id":"618341","title":"SPERMATOGENIC FAILURE 35; SPGF35","url":"https://www.omim.org/entry/618341"},{"mim_id":"618304","title":"GLUTAMINE-RICH PROTEIN 2; QRICH2","url":"https://www.omim.org/entry/618304"},{"mim_id":"258150","title":"SPERMATOGENIC FAILURE 1; SPGF1","url":"https://www.omim.org/entry/258150"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Uncertain","locations":[{"location":"Nucleoplasm","reliability":"Uncertain"},{"location":"Nuclear membrane","reliability":"Uncertain"},{"location":"Vesicles","reliability":"Additional"}],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"testis","ntpm":21.3}],"url":"https://www.proteinatlas.org/search/QRICH2"},"hgnc":{"alias_symbol":["DKFZP434P0316"],"prev_symbol":[]},"alphafold":{"accession":"Q9H0J4","domains":[],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0J4","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0J4-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q9H0J4-F1-predicted_aligned_error_v6.png","plddt_mean":44.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=QRICH2","jax_strain_url":"https://www.jax.org/strain/search?query=QRICH2"},"sequence":{"accession":"Q9H0J4","fasta_url":"https://rest.uniprot.org/uniprotkb/Q9H0J4.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q9H0J4/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q9H0J4"}},"corpus_meta":[{"pmid":"30683861","id":"PMC_30683861","title":"Loss-of-function mutations in QRICH2 cause male infertility with multiple morphological abnormalities of the sperm flagella.","date":"2019","source":"Nature communications","url":"https://pubmed.ncbi.nlm.nih.gov/30683861","citation_count":128,"is_preprint":false},{"pmid":"34089056","id":"PMC_34089056","title":"Exome sequencing reveals variants in known and novel candidate genes for severe sperm motility disorders.","date":"2021","source":"Human reproduction (Oxford, England)","url":"https://pubmed.ncbi.nlm.nih.gov/34089056","citation_count":51,"is_preprint":false},{"pmid":"15937959","id":"PMC_15937959","title":"Loss of heterozygosity and transcriptome analyses of a 1.2 Mb candidate ovarian cancer tumor suppressor locus region at 17q25.1-q25.2.","date":"2005","source":"Molecular carcinogenesis","url":"https://pubmed.ncbi.nlm.nih.gov/15937959","citation_count":49,"is_preprint":false},{"pmid":"34415320","id":"PMC_34415320","title":"Loss-of-function missense variant of AKAP4 induced male infertility through reduced interaction with QRICH2 during sperm flagella development.","date":"2021","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/34415320","citation_count":35,"is_preprint":false},{"pmid":"36017582","id":"PMC_36017582","title":"Whole-genome sequencing identifies new candidate genes for nonobstructive azoospermia.","date":"2022","source":"Andrology","url":"https://pubmed.ncbi.nlm.nih.gov/36017582","citation_count":33,"is_preprint":false},{"pmid":"31292949","id":"PMC_31292949","title":"Whole exome sequencing of men with multiple morphological abnormalities of the sperm flagella reveals novel homozygous QRICH2 mutations.","date":"2019","source":"Clinical genetics","url":"https://pubmed.ncbi.nlm.nih.gov/31292949","citation_count":29,"is_preprint":false},{"pmid":"37352829","id":"PMC_37352829","title":"CFAP70 is a solid and valuable target for the genetic diagnosis of oligo-astheno-teratozoospermia in infertile men.","date":"2023","source":"EBioMedicine","url":"https://pubmed.ncbi.nlm.nih.gov/37352829","citation_count":22,"is_preprint":false},{"pmid":"31969344","id":"PMC_31969344","title":"Black Raspberry Inhibits Oral Tumors in Mice Treated with the Tobacco Smoke Constituent Dibenzo(def,p)chrysene Via Genetic and Epigenetic Alterations.","date":"2020","source":"Cancer prevention research (Philadelphia, Pa.)","url":"https://pubmed.ncbi.nlm.nih.gov/31969344","citation_count":18,"is_preprint":false},{"pmid":"32439377","id":"PMC_32439377","title":"Multiple morphological abnormalities of the sperm flagella (MMAF)-associated genes: The relationships between genetic variation and litter size in goats.","date":"2020","source":"Gene","url":"https://pubmed.ncbi.nlm.nih.gov/32439377","citation_count":16,"is_preprint":false},{"pmid":"35255804","id":"PMC_35255804","title":"A 1-bp deletion in bovine QRICH2 causes low sperm count and immotile sperm with multiple morphological abnormalities.","date":"2022","source":"Genetics, selection, evolution : GSE","url":"https://pubmed.ncbi.nlm.nih.gov/35255804","citation_count":11,"is_preprint":false},{"pmid":"35886074","id":"PMC_35886074","title":"Further Insights on RNA Expression and Sperm Motility.","date":"2022","source":"Genes","url":"https://pubmed.ncbi.nlm.nih.gov/35886074","citation_count":11,"is_preprint":false},{"pmid":"36502923","id":"PMC_36502923","title":"Trio-based exome sequencing broaden the genetic spectrum in keratoconus.","date":"2022","source":"Experimental eye research","url":"https://pubmed.ncbi.nlm.nih.gov/36502923","citation_count":11,"is_preprint":false},{"pmid":"38597976","id":"PMC_38597976","title":"Metabolic profiling identifies Qrich2 as a novel glutamine sensor that regulates microtubule glutamylation and mitochondrial function in mouse sperm.","date":"2024","source":"Cellular and molecular life sciences : CMLS","url":"https://pubmed.ncbi.nlm.nih.gov/38597976","citation_count":7,"is_preprint":false},{"pmid":"32461543","id":"PMC_32461543","title":"Whole Exome Sequencing of Multiple Atypical Meningiomas in a Patient without History of Neurofibromatosis Type II: A Case Report.","date":"2020","source":"The American journal of case reports","url":"https://pubmed.ncbi.nlm.nih.gov/32461543","citation_count":5,"is_preprint":false},{"pmid":"37338096","id":"PMC_37338096","title":"Cerebrospinal Fluid Protein Biomarker Discovery in CLN3.","date":"2023","source":"Journal of proteome research","url":"https://pubmed.ncbi.nlm.nih.gov/37338096","citation_count":4,"is_preprint":false},{"pmid":"38772286","id":"PMC_38772286","title":"A Key regulatory protein QRICH2 governing sperm function with profound antioxidant properties, enhancing sperm viability.","date":"2024","source":"Reproductive biology","url":"https://pubmed.ncbi.nlm.nih.gov/38772286","citation_count":3,"is_preprint":false},{"pmid":"38243319","id":"PMC_38243319","title":"Genomics and tumor microenvironment of breast mucoepidermoid carcinoma based on whole-exome and RNA sequencing.","date":"2024","source":"Diagnostic pathology","url":"https://pubmed.ncbi.nlm.nih.gov/38243319","citation_count":3,"is_preprint":false},{"pmid":"40107860","id":"PMC_40107860","title":"Genetic variants in QRICH2 gene among Jordanians with sperm motility disorders.","date":"2025","source":"The Libyan journal of medicine","url":"https://pubmed.ncbi.nlm.nih.gov/40107860","citation_count":0,"is_preprint":false},{"pmid":"41575150","id":"PMC_41575150","title":"Exploring QRICH2 as a potential male contraceptive target.","date":"2026","source":"Reproduction (Cambridge, England)","url":"https://pubmed.ncbi.nlm.nih.gov/41575150","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":13618,"output_tokens":2017,"usd":0.035555,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8992,"output_tokens":2671,"usd":0.055868,"stage2_stop_reason":"end_turn"},"total_usd":0.091423,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2019,\n      \"finding\": \"QRICH2 is required for sperm flagellar formation; loss-of-function mutations cause MMAF in humans and Qrich2 knockout male mice show MMAF phenotype and sterility. Proteomic analysis of KO vs wild-type testes revealed that QRICH2 stabilizes and enhances expression of proteins related to flagellar development.\",\n      \"method\": \"CRISPR-Cas9 knockout mice, proteomic analysis of testes, in vitro experiments\",\n      \"journal\": \"Nature communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — KO mouse model with defined cellular phenotype, proteomic analysis, and in vitro confirmation; replicated across two independent families\",\n      \"pmids\": [\"30683861\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Homozygous loss-of-function variants in QRICH2 (nonsense mutations c.3501C>G and c.4614C>G) confirmed as causative for MMAF syndrome; heterozygous QRICH2 variants were found at comparable rates in MMAF patients and controls, indicating heterozygous variants alone are not pathogenic for MMAF.\",\n      \"method\": \"Whole exome sequencing of 167 MMAF-affected subjects, variant analysis\",\n      \"journal\": \"Clinical genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — large cohort exome sequencing with negative control comparison; single methodology but rigorous cohort design\",\n      \"pmids\": [\"31292949\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"QRICH2 physically interacts with AKAP4 (A-kinase anchor protein 4) in sperm; co-localization and co-immunoprecipitation demonstrated their interaction, and a hemizygous loss-of-function AKAP4 variant reduces QRICH2 protein expression in spermatozoa, indicating AKAP4 is required for maintaining QRICH2 expression and that their interaction is necessary for fibrous sheath formation.\",\n      \"method\": \"Immunofluorescence co-localization, co-immunoprecipitation (Co-IP) in HEK-293T cells, protein expression analysis in patient spermatozoa\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP and immunofluorescence in two systems (cell line + patient sperm), single lab, two orthogonal methods\",\n      \"pmids\": [\"34415320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A 1-bp deletion causing a frameshift and premature termination codon in bovine QRICH2 leads to low sperm count and immotile sperm with multiple morphological abnormalities of the flagellum; the mutant transcript undergoes nonsense-mediated mRNA decay as shown by testis transcriptome analysis.\",\n      \"method\": \"Genome sequencing of affected bull, testis transcriptome analysis (nonsense-mediated decay), semen analysis\",\n      \"journal\": \"Genetics, selection, evolution : GSE\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional variant confirmed in two independent homozygous bulls, transcriptome evidence for NMD, orthogonal semen phenotyping\",\n      \"pmids\": [\"35255804\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"QRICH2 acts as a glutamine (Gln) sensor in sperm; Qrich2 KO mice show reduced tubulin glutamylation and microtubule instability in sperm flagella, dysregulated glutamine/glutamate (Gln/Glu) metabolism with accumulated Gln and reduced Glu, and mislocalization of mitochondrial marker proteins in flagella contributing to reduced mitochondrial function and sperm motility. Dietary Gln/Glu deprivation phenocopied Qrich2 KO mice.\",\n      \"method\": \"Qrich2 KO mouse model, metabolic profiling, tubulin glutamylation assays, mitochondrial localization experiments, dietary intervention rescue experiment\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse model with multiple orthogonal assays and dietary phenocopy experiment; single lab\",\n      \"pmids\": [\"38597976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"QRICH2 has antioxidant properties that protect spermatids from ROS-induced damage; Qrich2 KO mice show elevated ROS levels, DNA damage in spermatids, increased autophagy and apoptosis, and reduced sperm count. Incubation with purified N-terminal QRICH2 protein exhibited antioxidant activity in vitro, enhancing spermatozoa viability and motility.\",\n      \"method\": \"HE staining, immunofluorescence, flow cytometry, single sperm metabolism analysis in Qrich2 KO mice; in vitro incubation with purified N-terminal QRICH2 protein\",\n      \"journal\": \"Reproductive biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO mouse phenotyping with multiple assays and in vitro protein function validation; single lab\",\n      \"pmids\": [\"38772286\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"CFAP70 regulates sperm flagella biogenesis partially by controlling the expression of QRICH2; Cfap70 KO mice show reduced QRICH2 expression levels, placing CFAP70 upstream of QRICH2 in the flagellar assembly pathway.\",\n      \"method\": \"Cfap70 KO mouse model, protein expression analysis\",\n      \"journal\": \"EBioMedicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic epistasis via KO mouse model; single lab, single method for the QRICH2-specific finding\",\n      \"pmids\": [\"37352829\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2026,\n      \"finding\": \"Human QRICH2 has no paralogs, is conserved across mammals with two functional domains, is restricted to the testes at the protein level, localizes to different cellular compartments throughout spermatogenesis, and acts as a cytoskeletal component in mature sperm in both the head and flagellum.\",\n      \"method\": \"Mass spectrometry isoform identification, in silico paralog/conservation analysis, immunodetection across 12 human organs, proteomic dataset analysis\",\n      \"journal\": \"Reproduction (Cambridge, England)\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — immunodetection and proteomics across multiple tissues and developmental stages; single lab, multiple methods\",\n      \"pmids\": [\"41575150\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"QRICH2 is a testis-specific cytoskeletal protein essential for sperm flagellar biogenesis that stabilizes flagellar proteins, physically interacts with AKAP4 at the fibrous sheath, regulates tubulin glutamylation and microtubule stability through glutamine/glutamate metabolism sensing, and protects spermatids from ROS-induced damage via antioxidant activity; loss-of-function causes multiple morphological abnormalities of the sperm flagella (MMAF) and male infertility in humans, mice, and cattle, with CFAP70 acting upstream of QRICH2 in the flagellar assembly pathway.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"QRICH2 is a testis-restricted cytoskeletal protein essential for sperm flagellar biogenesis, whose loss causes multiple morphological abnormalities of the sperm flagella (MMAF) and male infertility across humans, mice, and cattle [#0, #1, #3]. Mechanistically, QRICH2 stabilizes and sustains the expression of flagellar development proteins [#0] and physically interacts with AKAP4 at the fibrous sheath, an interaction required for fibrous sheath formation and for maintaining QRICH2 protein levels in spermatozoa [#2]. QRICH2 functions as a glutamine sensor that couples Gln/Glu metabolism to tubulin glutamylation and microtubule stability in the flagellum, with its loss producing dysregulated Gln/Glu balance, mitochondrial protein mislocalization, and impaired motility — a phenotype reproduced by dietary Gln/Glu deprivation [#4]. Its N-terminal region carries antioxidant activity that protects spermatids from ROS-induced DNA damage, autophagy, and apoptosis [#5]. QRICH2 acts downstream of CFAP70 in the flagellar assembly pathway [#6] and localizes to distinct compartments across spermatogenesis, residing in both the head and flagellum of mature sperm [#7].\",\n  \"teleology\": [\n    {\n      \"year\": 2019,\n      \"claim\": \"Established QRICH2 as a gene required for sperm flagellar formation and defined its molecular role as a stabilizer of flagellar development proteins, linking it directly to human MMAF and infertility.\",\n      \"evidence\": \"CRISPR-Cas9 knockout mice with MMAF phenotype plus proteomic analysis of testes and human variant identification\",\n      \"pmids\": [\"30683861\", \"31292949\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Which specific flagellar proteins QRICH2 stabilizes was not resolved at the molecular level\", \"Heterozygous variants alone are not pathogenic, leaving the threshold of QRICH2 dose unclear\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified a direct physical partner, showing QRICH2 interacts with AKAP4 at the fibrous sheath and that this interaction maintains QRICH2 expression — connecting QRICH2 to a defined flagellar structural assembly.\",\n      \"evidence\": \"Reciprocal Co-IP and immunofluorescence co-localization in HEK-293T cells plus expression analysis in AKAP4-variant patient sperm\",\n      \"pmids\": [\"34415320\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Interaction interface and stoichiometry not mapped\", \"Whether the dependency is mutual or unidirectional not fully resolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated cross-species conservation of QRICH2 function by showing a frameshift variant causes MMAF in cattle via nonsense-mediated decay of the transcript.\",\n      \"evidence\": \"Genome sequencing of affected bulls, testis transcriptome NMD analysis, and semen phenotyping\",\n      \"pmids\": [\"35255804\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Does not add mechanistic detail beyond confirming loss-of-function phenotype\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Placed QRICH2 within a genetic hierarchy by showing CFAP70 acts upstream, controlling QRICH2 expression during flagellar assembly.\",\n      \"evidence\": \"Cfap70 knockout mouse model with QRICH2 protein expression analysis\",\n      \"pmids\": [\"37352829\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether CFAP70 regulates QRICH2 transcriptionally or post-translationally is unknown\", \"Direct versus indirect regulation not distinguished\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Defined a metabolic-sensing mechanism: QRICH2 acts as a glutamine sensor linking Gln/Glu metabolism to tubulin glutamylation, microtubule stability, and mitochondrial positioning in the flagellum.\",\n      \"evidence\": \"Qrich2 KO mouse with metabolic profiling, tubulin glutamylation assays, mitochondrial localization, and dietary Gln/Glu deprivation phenocopy\",\n      \"pmids\": [\"38597976\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular basis of Gln sensing by QRICH2 not structurally defined\", \"Direct enzymatic role in glutamylation versus regulatory role not separated\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Assigned a cytoprotective function: the QRICH2 N-terminus has intrinsic antioxidant activity protecting spermatids from ROS-induced damage.\",\n      \"evidence\": \"Qrich2 KO mouse phenotyping for ROS, DNA damage, autophagy and apoptosis plus in vitro incubation with purified N-terminal QRICH2 protein\",\n      \"pmids\": [\"38772286\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Biochemical mechanism of antioxidant activity not characterized\", \"Relationship between antioxidant and cytoskeletal functions not integrated\"]\n    },\n    {\n      \"year\": 2026,\n      \"claim\": \"Characterized QRICH2 as a paralog-free, mammal-conserved, testis-restricted protein with two functional domains that relocalizes across spermatogenesis and acts as a cytoskeletal component in both sperm head and flagellum.\",\n      \"evidence\": \"Mass spectrometry isoform identification, in silico conservation analysis, immunodetection across 12 human organs, and proteomic dataset analysis\",\n      \"pmids\": [\"41575150\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional contribution of QRICH2 in the sperm head not defined\", \"Domain-specific activities not mapped to localization changes\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the metabolic-sensing, antioxidant, and structural functions of QRICH2 are mechanistically integrated, and the molecular basis of its glutamine sensing, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of QRICH2 domains\", \"No defined enzymatic mechanism for glutamine sensing or antioxidant activity\", \"Direct flagellar protein clients not catalogued\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 7]},\n      {\"term_id\": \"GO:0005198\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0016209\", \"supporting_discovery_ids\": [5]},\n      {\"term_id\": \"GO:0140299\", \"supporting_discovery_ids\": [4]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [7]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [0, 1]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [0, 6]}\n    ],\n    \"complexes\": [\"fibrous sheath\"],\n    \"partners\": [\"AKAP4\", \"CFAP70\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}