Each column keeps its native condition scope. Initial features are displayed alphabetically, not ranked by clinical importance. Counts remain separate, and an empty cell does not mean a feature cannot occur.
"},"coverage":{"countRecords":2,"emptyColumnKeys":[],"hpoRelease":"2026-06-23","narrativeSourceChanges":[],"records":5,"sourceGroups":{"omim":3,"orphanet":0,"published":2}},"features":[{"hpoId":"HP:0000502","label":"Abnormal conjunctiva morphology","primary":false},{"hpoId":"HP:0000969","label":"Edema","primary":false},{"hpoId":"HP:0025092","label":"Epidermal acanthosis","primary":false},{"hpoId":"HP:0040009","label":"Hyperparakeratosis","primary":false},{"hpoId":"HP:0002745","label":"Oral leukoplakia","primary":false}],"ledeHtml":"White sponge nevus is a condition characterized by the formation of white patches of tissue called nevi (singular: nevus) that appear as thickened, velvety, sponge-like tissue. The nevi are most commonly found on the moist lining of the mouth (oral mucosa), especially on the inside of the cheeks (buccal mucosa). Affected individuals usually develop multiple nevi. Rarely, white sponge nevi also occur on the mucosae (singular: mucosa) of the nose, esophagus, genitals, or anus. The nevi are caused by a noncancerous (benign) overgrowth of cells.","mondoId":"MONDO:0015748","records":[{"frequencyKind":"count","key":"4f54baa38fcfda58b4f0315dc4320bc23a5908f3a8d4fa423d8850fde4cf0208","raw":{"aspect":"P","body_system":"head_and_neck","disease_id":"OMIM:193900","disease_name":"White sponge nevus 1","evidence":"PCS","frequency_raw":"0/8","hpo_id":"HP:0000502","is_excluded":true,"label":"Abnormal conjunctiva morphology","onset_id":null,"reference":"PMID:7493030","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"reported","key":"90024519c177846bdc8128705e710a05069cb03501dca19909210ce20df4787b","raw":{"aspect":"P","body_system":"skin","disease_id":"OMIM:615785","disease_name":"White sponge nevus 2","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0040009","is_excluded":false,"label":"Hyperparakeratosis","onset_id":null,"reference":"OMIM:615785","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"count","key":"a54a66a73a407f18475a0467ffd5ca1a40d5a67f77db68668b20b309f6564b84","raw":{"aspect":"P","body_system":"head_and_neck","disease_id":"OMIM:193900","disease_name":"White sponge nevus 1","evidence":"PCS","frequency_raw":"8/8","hpo_id":"HP:0002745","is_excluded":false,"label":"Oral leukoplakia","onset_id":null,"reference":"PMID:7493030","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"reported","key":"e94238d856e8e974e91302745e8eba0c478daf422eb62640973c9d2b745ba2e7","raw":{"aspect":"P","body_system":"metabolic","disease_id":"OMIM:615785","disease_name":"White sponge nevus 2","evidence":"IEA","frequency_raw":null,"hpo_id":"HP:0000969","is_excluded":false,"label":"Edema","onset_id":null,"reference":"OMIM:615785","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"eceea6d8108ca8b277ecdc4c947e856d5d5379af8686d83e77bd1c993b8b238e","raw":{"aspect":"P","body_system":"skin","disease_id":"OMIM:615785","disease_name":"White sponge nevus 2","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0025092","is_excluded":false,"label":"Epidermal acanthosis","onset_id":null,"reference":"OMIM:615785","source_release":"2026-06-23"},"sourceGroups":["omim"]}],"referenceLabels":{},"references":{"causeHtml":"","identityNote":"MONDO cross-references identify native condition entries. Ancestor membership does not transfer phenotype values between groups.","importantHtml":""},"sections":[{"bodyHtml":"Mutations in the KRT4 or KRT13 gene cause white sponge nevus. These genes provide instructions for making proteins called keratins. Keratins are a group of tough, fibrous proteins that form the structural framework of epithelial cells, which are cells that line the surfaces and cavities of the body and make up the different mucosae. The keratin 4 protein (produced from the KRT4 gene) and the keratin 13 protein (produced from the KRT13 gene) partner together to form molecules known as intermediate filaments. These filaments assemble into networks that provide strength and resilience to the different mucosae. Networks of intermediate filaments protect the mucosae from being damaged by friction or other everyday physical stresses.
Mutations in the KRT4 or KRT13 gene disrupt the structure of the keratin protein. As a result, keratin 4 and keratin 13 are mismatched and do not fit together properly, leading to the formation of irregular intermediate filaments that are easily damaged with little friction or trauma. Fragile intermediate filaments in the oral mucosa might be damaged when eating or brushing one's teeth. Damage to intermediate filaments leads to inflammation and promotes the abnormal growth and division (proliferation) of epithelial cells, causing the mucosae to thicken and resulting in white sponge nevus.
","key":"forms","title":"What causes White sponge nevus?"},{"bodyHtml":"White sponge nevus can be present from birth but usually first appears during early childhood. The size and location of the nevi can change over time. In the oral mucosa, both sides of the mouth are usually affected. The nevi are generally painless, but the folds of extra tissue can promote bacterial growth, which can lead to infection that may cause discomfort. The altered texture and appearance of the affected tissue, especially the oral mucosa, can be bothersome for some affected individuals.
Source: MedlinePlus Genetics
","key":"overview","title":"Condition overview"}],"sharedSources":[],"slug":"white-sponge-nevus","sourceDocuments":[{"name":"White sponge nevus","reviewed":"2014-02","sections":{"causes":{"fetchedAt":"2026-10-20T20:25:48.884530+00:00","label":"Causes","pageSha256":"e543028ebdaeb84dc1108ea4a9eeaf68005b1660571f9a020882fb004b1fc7ef","sourceUrl":"https://medlineplus.gov/genetics/condition/white-sponge-nevus/#causes","status":"available"}},"source_release":"2026-10-01","url":"https://medlineplus.gov/genetics/condition/white-sponge-nevus"}],"sourceNote":"MedlinePlus descriptions and Causes; original HPO annotations.","takeawayHtml":"Cause explanations are from MedlinePlus Genetics. Feature values below retain their original sources and patient groups.","title":"White sponge nevus"},"schemaVersion":1}