{"gene":"PHKA1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1989,"finding":"PHKA1 (alpha subunit of phosphorylase kinase) was mapped to the human X chromosome at region Xq12-q13 by Southern blot analysis of rodent-human somatic cell hybrid panels and in situ chromosomal hybridization, establishing it as the candidate gene for X-linked phosphorylase kinase (PHK) deficiency in muscle.","method":"Southern blot of somatic cell hybrid panels; in situ chromosomal hybridization","journal":"American journal of human genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — two orthogonal mapping methods, independently replicated in subsequent literature","pmids":["2757032"],"is_preprint":false},{"year":1992,"finding":"A liver-specific alpha-subunit gene of phosphorylase kinase (PHKA) was localized to the distal region of chromosome Xp by in situ hybridization, distinct from the muscle PHKA1 locus at Xq12-q13, identifying it as the candidate gene for X-linked liver glycogenosis (XLG).","method":"In situ hybridization with cohybridization of X-centromere probe","journal":"Cytogenetics and cell genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional candidate inference, single lab but two probes used","pmids":["1505214"],"is_preprint":false},{"year":2003,"finding":"A PHKA1 missense mutation (D299V) in one male patient was shown to cause muscle phosphorylase kinase deficiency, establishing PHKA1 as the causative gene for muscle-specific PHK deficiency; the study also determined the structure of the PHKG1 gene and found that mutations in PHKA1, PHKG1, and other PHK subunit genes explain only a minority of muscle glycogenosis cases with low PHK activity.","method":"Sequencing of coding regions, splice sites, and promoters of PHKA1, PHKB, PHKG1, CALM1/2/3, PYGM, PRKAG3 in six patients","journal":"European journal of human genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mutation identified in patient with enzymatic deficiency; multi-gene sequencing in multiple patients; single lab","pmids":["12825073"],"is_preprint":false},{"year":2005,"finding":"A frameshift mutation in PHKA1 was identified in a male patient with myopathy and completely absent muscle phosphorylase kinase activity, confirming that loss-of-function of the PHKA1-encoded alpha subunit directly abolishes PHK enzymatic activity in muscle.","method":"Mutation analysis (sequencing) correlated with enzyme activity assay in patient muscle","journal":"American journal of medical genetics. Part A","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — direct genotype-to-enzyme-activity correlation in a single patient, single lab","pmids":["15637709"],"is_preprint":false},{"year":2021,"finding":"PHKA1 encodes the αM (muscle) subunit of phosphorylase kinase, a multimeric protein complex responsible for controlling glycogen breakdown in muscle; a novel PHKA1 mutation was shown to cause progressive myopathy, exercise intolerance, and cognitive impairment, expanding the phenotypic consequence of loss of this subunit to include potential CNS involvement.","method":"Clinical and genetic characterization; PHKA1 mutation identified in siblings with biochemically confirmed PHK deficiency","journal":"Journal of the neurological sciences","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single family, clinical-genetic correlation without in vitro mechanistic follow-up","pmids":["33799212"],"is_preprint":false},{"year":2025,"finding":"siRNA-mediated knockdown of PHKA1 in MDA-MB-231 and MCF-7 breast cancer cells led to decreased proliferation, invasion, migration, and stem-like properties, reduced expression of mesenchymal and cell-cycle markers, and diminished glycolytic activity and mitochondrial function, placing PHKA1 as a functional contributor to glycolytic metabolic reprogramming in cancer cells.","method":"siRNA knockdown; glycolysis stress assay; mitochondrial stress assay; marker expression analysis","journal":"Biochimica et biophysica acta. Molecular cell research","confidence":"Low","confidence_rationale":"Tier 3 / Weak — single lab, KD with phenotypic readouts but no direct pathway placement or in vitro reconstitution of mechanism","pmids":["40882873"],"is_preprint":false}],"current_model":"PHKA1 encodes the muscle-specific alpha (αM) subunit of phosphorylase kinase (PHK), a multimeric enzyme complex that activates glycogen phosphorylase to control glycogen breakdown in muscle; loss-of-function mutations in PHKA1 abolish muscle PHK enzymatic activity, causing X-linked glycogen storage disease (GSD IXd/IXα1) with exercise intolerance and myopathy, and the gene maps to Xq12-q13 distinct from a liver-specific PHKA paralog at Xp."},"narrative":{"mechanistic_narrative":"PHKA1 encodes the muscle (αM) subunit of phosphorylase kinase, a multimeric enzyme complex that controls glycogen breakdown in muscle [PMID:2757032, PMID:33799212]. The gene maps to Xq12-q13, distinct from a liver-specific α-subunit paralog localized to distal Xp, providing the molecular basis for tissue-specific X-linked phosphorylase kinase deficiencies [PMID:2757032, PMID:1505214]. Loss-of-function mutations in PHKA1 directly abolish muscle PHK enzymatic activity: a frameshift mutation produced completely absent muscle PHK activity, and a missense mutation (D299V) was established as causative for muscle-specific PHK deficiency, defining PHKA1 as the gene underlying X-linked muscle glycogenosis with myopathy and exercise intolerance [PMID:12825073, PMID:15637709]. Beyond its established role in muscle glycogenolysis, the biochemical mechanism by which the αM subunit assembles into and regulates the PHK holoenzyme has not been characterized in the available corpus.","teleology":[{"year":1989,"claim":"Pinpointing the chromosomal location of the muscle PHK alpha subunit was needed to identify the gene responsible for X-linked muscle PHK deficiency; mapping placed PHKA1 at Xq12-q13.","evidence":"Southern blot of rodent-human somatic cell hybrid panels and in situ chromosomal hybridization","pmids":["2757032"],"confidence":"High","gaps":["Mapping alone did not demonstrate causative mutations","No protein-level characterization of the subunit"]},{"year":1992,"claim":"Distinguishing the muscle from the liver alpha-subunit locus clarified why PHK deficiencies are tissue-specific; the liver-specific PHKA gene was localized to distal Xp, separate from PHKA1 at Xq.","evidence":"In situ hybridization with cohybridization of an X-centromere probe","pmids":["1505214"],"confidence":"Medium","gaps":["Functional candidacy inferred from localization, not from mutation in patients","Single lab"]},{"year":2003,"claim":"Direct genetic proof was needed that PHKA1 mutations cause muscle PHK deficiency; a D299V missense mutation in a patient with enzymatic deficiency established causation, while broader sequencing showed known PHK subunit genes explain only a minority of low-PHK-activity muscle glycogenosis.","evidence":"Sequencing of PHKA1, PHKB, PHKG1, CALM1/2/3, PYGM, PRKAG3 in six patients","pmids":["12825073"],"confidence":"Medium","gaps":["Single mutant patient for PHKA1","Genetic cause unexplained in most low-PHK-activity cases","No in vitro reconstitution of mutant subunit"]},{"year":2005,"claim":"Whether PHKA1 loss-of-function fully abolishes enzyme activity was unresolved; a frameshift mutation correlated with completely absent muscle PHK activity, confirming the αM subunit is required for holoenzyme function.","evidence":"Mutation sequencing correlated with PHK enzyme activity assay in patient muscle","pmids":["15637709"],"confidence":"Medium","gaps":["Single patient","Mechanism of subunit contribution to catalysis not defined"]},{"year":2021,"claim":"The phenotypic spectrum of PHKA1 loss was extended beyond myopathy; a novel mutation in siblings was associated with progressive myopathy, exercise intolerance, and cognitive impairment.","evidence":"Clinical and genetic characterization of siblings with biochemically confirmed PHK deficiency","pmids":["33799212"],"confidence":"Low","gaps":["Single family without in vitro mechanistic follow-up","CNS involvement causation not established","No molecular mechanism for cognitive phenotype"]},{"year":2025,"claim":"A possible role outside muscle glycogenolysis was explored; PHKA1 knockdown in breast cancer cells reduced proliferation, invasion, migration, stem-like properties, glycolysis, and mitochondrial function, implicating it in glycolytic metabolic reprogramming.","evidence":"siRNA knockdown in MDA-MB-231 and MCF-7 cells with glycolysis and mitochondrial stress assays and marker analysis","pmids":["40882873"],"confidence":"Low","gaps":["Single lab with phenotypic readouts only","No direct pathway placement or mechanistic reconstitution","Relationship to PHK holoenzyme function in cancer unknown"]},{"year":null,"claim":"How the αM subunit assembles into and regulates the phosphorylase kinase holoenzyme at the structural and biochemical level, and whether the cancer-associated metabolic role is mechanistically connected to its glycogenolytic function, remain unresolved.","evidence":"","pmids":[],"confidence":"Low","gaps":["No structural model of the αM subunit within PHK","Mechanism linking PHKA1 to cancer glycolysis undefined","Most low-PHK-activity muscle glycogenosis cases remain genetically unexplained"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[3,4]}],"localization":[],"pathway":[{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[0,4]}],"complexes":["phosphorylase kinase"],"partners":[],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P46020","full_name":"Phosphorylase b kinase regulatory subunit alpha, skeletal muscle isoform","aliases":[],"length_aa":1223,"mass_kda":137.3,"function":"Phosphorylase b kinase catalyzes the phosphorylation of serine in certain substrates, including troponin I. The alpha chain may bind calmodulin","subcellular_location":"Cell membrane","url":"https://www.uniprot.org/uniprotkb/P46020/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PHKA1","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":[{"gene":"PHKG2","stoichiometry":10.0},{"gene":"CALM1","stoichiometry":0.2},{"gene":"CALM2","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PHKA1","total_profiled":1310},"omim":[{"mim_id":"611556","title":"GLYCOGEN STORAGE DISEASE 0, MUSCLE; GSD0B","url":"https://www.omim.org/entry/611556"},{"mim_id":"314670","title":"X INACTIVATION-SPECIFIC TRANSCRIPT; XIST","url":"https://www.omim.org/entry/314670"},{"mim_id":"313650","title":"TAF1 RNA POLYMERASE II, TATA BOX-BINDING PROTEIN-ASSOCIATED FACTOR, 250-KD; TAF1","url":"https://www.omim.org/entry/313650"},{"mim_id":"312760","title":"RIBOSOMAL PROTEIN S4, X-LINKED; RPS4X","url":"https://www.omim.org/entry/312760"},{"mim_id":"311870","title":"PHOSPHORYLASE KINASE, MUSCLE, ALPHA-1 SUBUNIT; PHKA1","url":"https://www.omim.org/entry/311870"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Vesicles","reliability":"Approved"},{"location":"Cytosol","reliability":"Approved"}],"tissue_specificity":"Group enriched","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"parathyroid gland","ntpm":30.1},{"tissue":"skeletal muscle","ntpm":96.1},{"tissue":"tongue","ntpm":83.3}],"url":"https://www.proteinatlas.org/search/PHKA1"},"hgnc":{"alias_symbol":[],"prev_symbol":["PHKA"]},"alphafold":{"accession":"P46020","domains":[{"cath_id":"1.50.10.10","chopping":"7-431","consensus_level":"medium","plddt":93.9153,"start":7,"end":431},{"cath_id":"-","chopping":"436-623","consensus_level":"medium","plddt":90.5059,"start":436,"end":623},{"cath_id":"-","chopping":"837-972","consensus_level":"medium","plddt":86.8392,"start":837,"end":972},{"cath_id":"-","chopping":"1069-1214","consensus_level":"high","plddt":90.5799,"start":1069,"end":1214}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P46020","model_url":"https://alphafold.ebi.ac.uk/files/AF-P46020-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P46020-F1-predicted_aligned_error_v6.png","plddt_mean":81.69},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PHKA1","jax_strain_url":"https://www.jax.org/strain/search?query=PHKA1"},"sequence":{"accession":"P46020","fasta_url":"https://rest.uniprot.org/uniprotkb/P46020.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P46020/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P46020"}},"corpus_meta":[{"pmid":"8401491","id":"PMC_8401491","title":"2.6 Mb YAC contig of the human X inactivation center region in Xq13: physical linkage of the RPS4X, PHKA1, XIST and DXS128E genes.","date":"1993","source":"Human molecular genetics","url":"https://pubmed.ncbi.nlm.nih.gov/8401491","citation_count":63,"is_preprint":false},{"pmid":"2757032","id":"PMC_2757032","title":"Assignment of human genes for phosphorylase kinase subunits alpha (PHKA) to Xq12-q13 and beta (PHKB) to 16q12-q13.","date":"1989","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/2757032","citation_count":59,"is_preprint":false},{"pmid":"12825073","id":"PMC_12825073","title":"Muscle glycogenosis with low phosphorylase kinase activity: mutations in PHKA1, PHKG1 or six other candidate genes explain only a minority of cases.","date":"2003","source":"European journal of human genetics : EJHG","url":"https://pubmed.ncbi.nlm.nih.gov/12825073","citation_count":40,"is_preprint":false},{"pmid":"15637709","id":"PMC_15637709","title":"Myopathy and phosphorylase kinase deficiency caused by a mutation in the PHKA1 gene.","date":"2005","source":"American journal of medical genetics. Part A","url":"https://pubmed.ncbi.nlm.nih.gov/15637709","citation_count":31,"is_preprint":false},{"pmid":"1505214","id":"PMC_1505214","title":"Regional mapping of a liver alpha-subunit gene of phosphorylase kinase (PHKA) to the distal region of human chromosome Xp.","date":"1992","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/1505214","citation_count":26,"is_preprint":false},{"pmid":"33799212","id":"PMC_33799212","title":"A novel PHKA1 mutation associating myopathy and cognitive impairment: Expanding the spectrum of phosphorylase kinase b (PhK) deficiency.","date":"2021","source":"Journal of the neurological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/33799212","citation_count":10,"is_preprint":false},{"pmid":"35710611","id":"PMC_35710611","title":"A 78-year-old Japanese male with late-onset PHKA1-associated distal myopathy: Case report and literature review.","date":"2022","source":"Neuromuscular disorders : NMD","url":"https://pubmed.ncbi.nlm.nih.gov/35710611","citation_count":6,"is_preprint":false},{"pmid":"1424811","id":"PMC_1424811","title":"Assignment of the rabbit genes for alpha (PHKA) and beta (PHKB) phosphorylase kinase subunits.","date":"1992","source":"Cytogenetics and cell genetics","url":"https://pubmed.ncbi.nlm.nih.gov/1424811","citation_count":5,"is_preprint":false},{"pmid":"38764726","id":"PMC_38764726","title":"m6A modification of lncRNA PHKA1-AS1 enhances Actinin Alpha 4 stability and promotes non-small cell lung cancer metastasis.","date":"2024","source":"MedComm","url":"https://pubmed.ncbi.nlm.nih.gov/38764726","citation_count":2,"is_preprint":false},{"pmid":"7705849","id":"PMC_7705849","title":"Dinucleotide repeat polymorphism within the PHKA1 gene at Xq12-q13.","date":"1995","source":"Human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/7705849","citation_count":2,"is_preprint":false},{"pmid":"40882873","id":"PMC_40882873","title":"Unexplored gene PHKA1 interplays between glucose metabolism and breast cancer.","date":"2025","source":"Biochimica et biophysica acta. Molecular cell research","url":"https://pubmed.ncbi.nlm.nih.gov/40882873","citation_count":0,"is_preprint":false},{"pmid":"41213961","id":"PMC_41213961","title":"PHKA1-associated phosphorylase kinase deficiency: a monogenic disorder of exercise intolerance and myalgia.","date":"2025","source":"NPJ genomic medicine","url":"https://pubmed.ncbi.nlm.nih.gov/41213961","citation_count":0,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":6990,"output_tokens":1467,"usd":0.021487,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":8253,"output_tokens":2140,"usd":0.047383,"stage2_stop_reason":"end_turn"},"total_usd":0.06887,"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\": 1989,\n      \"finding\": \"PHKA1 (alpha subunit of phosphorylase kinase) was mapped to the human X chromosome at region Xq12-q13 by Southern blot analysis of rodent-human somatic cell hybrid panels and in situ chromosomal hybridization, establishing it as the candidate gene for X-linked phosphorylase kinase (PHK) deficiency in muscle.\",\n      \"method\": \"Southern blot of somatic cell hybrid panels; in situ chromosomal hybridization\",\n      \"journal\": \"American journal of human genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — two orthogonal mapping methods, independently replicated in subsequent literature\",\n      \"pmids\": [\"2757032\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1992,\n      \"finding\": \"A liver-specific alpha-subunit gene of phosphorylase kinase (PHKA) was localized to the distal region of chromosome Xp by in situ hybridization, distinct from the muscle PHKA1 locus at Xq12-q13, identifying it as the candidate gene for X-linked liver glycogenosis (XLG).\",\n      \"method\": \"In situ hybridization with cohybridization of X-centromere probe\",\n      \"journal\": \"Cytogenetics and cell genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional candidate inference, single lab but two probes used\",\n      \"pmids\": [\"1505214\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"A PHKA1 missense mutation (D299V) in one male patient was shown to cause muscle phosphorylase kinase deficiency, establishing PHKA1 as the causative gene for muscle-specific PHK deficiency; the study also determined the structure of the PHKG1 gene and found that mutations in PHKA1, PHKG1, and other PHK subunit genes explain only a minority of muscle glycogenosis cases with low PHK activity.\",\n      \"method\": \"Sequencing of coding regions, splice sites, and promoters of PHKA1, PHKB, PHKG1, CALM1/2/3, PYGM, PRKAG3 in six patients\",\n      \"journal\": \"European journal of human genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mutation identified in patient with enzymatic deficiency; multi-gene sequencing in multiple patients; single lab\",\n      \"pmids\": [\"12825073\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"A frameshift mutation in PHKA1 was identified in a male patient with myopathy and completely absent muscle phosphorylase kinase activity, confirming that loss-of-function of the PHKA1-encoded alpha subunit directly abolishes PHK enzymatic activity in muscle.\",\n      \"method\": \"Mutation analysis (sequencing) correlated with enzyme activity assay in patient muscle\",\n      \"journal\": \"American journal of medical genetics. Part A\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — direct genotype-to-enzyme-activity correlation in a single patient, single lab\",\n      \"pmids\": [\"15637709\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PHKA1 encodes the αM (muscle) subunit of phosphorylase kinase, a multimeric protein complex responsible for controlling glycogen breakdown in muscle; a novel PHKA1 mutation was shown to cause progressive myopathy, exercise intolerance, and cognitive impairment, expanding the phenotypic consequence of loss of this subunit to include potential CNS involvement.\",\n      \"method\": \"Clinical and genetic characterization; PHKA1 mutation identified in siblings with biochemically confirmed PHK deficiency\",\n      \"journal\": \"Journal of the neurological sciences\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single family, clinical-genetic correlation without in vitro mechanistic follow-up\",\n      \"pmids\": [\"33799212\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"siRNA-mediated knockdown of PHKA1 in MDA-MB-231 and MCF-7 breast cancer cells led to decreased proliferation, invasion, migration, and stem-like properties, reduced expression of mesenchymal and cell-cycle markers, and diminished glycolytic activity and mitochondrial function, placing PHKA1 as a functional contributor to glycolytic metabolic reprogramming in cancer cells.\",\n      \"method\": \"siRNA knockdown; glycolysis stress assay; mitochondrial stress assay; marker expression analysis\",\n      \"journal\": \"Biochimica et biophysica acta. Molecular cell research\",\n      \"confidence\": \"Low\",\n      \"confidence_rationale\": \"Tier 3 / Weak — single lab, KD with phenotypic readouts but no direct pathway placement or in vitro reconstitution of mechanism\",\n      \"pmids\": [\"40882873\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PHKA1 encodes the muscle-specific alpha (αM) subunit of phosphorylase kinase (PHK), a multimeric enzyme complex that activates glycogen phosphorylase to control glycogen breakdown in muscle; loss-of-function mutations in PHKA1 abolish muscle PHK enzymatic activity, causing X-linked glycogen storage disease (GSD IXd/IXα1) with exercise intolerance and myopathy, and the gene maps to Xq12-q13 distinct from a liver-specific PHKA paralog at Xp.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PHKA1 encodes the muscle (αM) subunit of phosphorylase kinase, a multimeric enzyme complex that controls glycogen breakdown in muscle [#0, #4]. The gene maps to Xq12-q13, distinct from a liver-specific α-subunit paralog localized to distal Xp, providing the molecular basis for tissue-specific X-linked phosphorylase kinase deficiencies [#0, #1]. Loss-of-function mutations in PHKA1 directly abolish muscle PHK enzymatic activity: a frameshift mutation produced completely absent muscle PHK activity, and a missense mutation (D299V) was established as causative for muscle-specific PHK deficiency, defining PHKA1 as the gene underlying X-linked muscle glycogenosis with myopathy and exercise intolerance [#2, #3]. Beyond its established role in muscle glycogenolysis, the biochemical mechanism by which the αM subunit assembles into and regulates the PHK holoenzyme has not been characterized in the available corpus.\",\n  \"teleology\": [\n    {\n      \"year\": 1989,\n      \"claim\": \"Pinpointing the chromosomal location of the muscle PHK alpha subunit was needed to identify the gene responsible for X-linked muscle PHK deficiency; mapping placed PHKA1 at Xq12-q13.\",\n      \"evidence\": \"Southern blot of rodent-human somatic cell hybrid panels and in situ chromosomal hybridization\",\n      \"pmids\": [\"2757032\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mapping alone did not demonstrate causative mutations\", \"No protein-level characterization of the subunit\"]\n    },\n    {\n      \"year\": 1992,\n      \"claim\": \"Distinguishing the muscle from the liver alpha-subunit locus clarified why PHK deficiencies are tissue-specific; the liver-specific PHKA gene was localized to distal Xp, separate from PHKA1 at Xq.\",\n      \"evidence\": \"In situ hybridization with cohybridization of an X-centromere probe\",\n      \"pmids\": [\"1505214\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional candidacy inferred from localization, not from mutation in patients\", \"Single lab\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Direct genetic proof was needed that PHKA1 mutations cause muscle PHK deficiency; a D299V missense mutation in a patient with enzymatic deficiency established causation, while broader sequencing showed known PHK subunit genes explain only a minority of low-PHK-activity muscle glycogenosis.\",\n      \"evidence\": \"Sequencing of PHKA1, PHKB, PHKG1, CALM1/2/3, PYGM, PRKAG3 in six patients\",\n      \"pmids\": [\"12825073\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single mutant patient for PHKA1\", \"Genetic cause unexplained in most low-PHK-activity cases\", \"No in vitro reconstitution of mutant subunit\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Whether PHKA1 loss-of-function fully abolishes enzyme activity was unresolved; a frameshift mutation correlated with completely absent muscle PHK activity, confirming the αM subunit is required for holoenzyme function.\",\n      \"evidence\": \"Mutation sequencing correlated with PHK enzyme activity assay in patient muscle\",\n      \"pmids\": [\"15637709\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single patient\", \"Mechanism of subunit contribution to catalysis not defined\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"The phenotypic spectrum of PHKA1 loss was extended beyond myopathy; a novel mutation in siblings was associated with progressive myopathy, exercise intolerance, and cognitive impairment.\",\n      \"evidence\": \"Clinical and genetic characterization of siblings with biochemically confirmed PHK deficiency\",\n      \"pmids\": [\"33799212\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single family without in vitro mechanistic follow-up\", \"CNS involvement causation not established\", \"No molecular mechanism for cognitive phenotype\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"A possible role outside muscle glycogenolysis was explored; PHKA1 knockdown in breast cancer cells reduced proliferation, invasion, migration, stem-like properties, glycolysis, and mitochondrial function, implicating it in glycolytic metabolic reprogramming.\",\n      \"evidence\": \"siRNA knockdown in MDA-MB-231 and MCF-7 cells with glycolysis and mitochondrial stress assays and marker analysis\",\n      \"pmids\": [\"40882873\"],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"Single lab with phenotypic readouts only\", \"No direct pathway placement or mechanistic reconstitution\", \"Relationship to PHK holoenzyme function in cancer unknown\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How the αM subunit assembles into and regulates the phosphorylase kinase holoenzyme at the structural and biochemical level, and whether the cancer-associated metabolic role is mechanistically connected to its glycogenolytic function, remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No structural model of the αM subunit within PHK\", \"Mechanism linking PHKA1 to cancer glycolysis undefined\", \"Most low-PHK-activity muscle glycogenosis cases remain genetically unexplained\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [3, 4]}\n    ],\n    \"localization\": [],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [0, 4]}\n    ],\n    \"complexes\": [\"phosphorylase kinase\"],\n    \"partners\": [],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":3,"faith_total":3,"faith_pct":100.0}}