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":0,"emptyColumnKeys":[],"hpoRelease":"2026-06-23","narrativeSourceChanges":[],"records":9,"sourceGroups":{"omim":9,"orphanet":0,"published":0}},"features":[{"hpoId":"HP:0002110","label":"Bronchiectasis","primary":false},{"hpoId":"HP:0000389","label":"Chronic otitis media","primary":false},{"hpoId":"HP:0011109","label":"Chronic sinusitis","primary":false},{"hpoId":"HP:0001083","label":"Ectopia lentis","primary":false},{"hpoId":"HP:0002097","label":"Emphysema","primary":false},{"hpoId":"HP:0100582","label":"Nasal polyposis","primary":false},{"hpoId":"HP:0002837","label":"Recurrent bronchitis","primary":false},{"hpoId":"HP:0200042","label":"Skin ulcer","primary":false},{"hpoId":"HP:0011950","label":"Unusual bronchiolitis","primary":false}],"ledeHtml":"Bare lymphocyte syndrome type I (BLS I) is an inherited disorder of the immune system (primary immunodeficiency). Immunodeficiencies are conditions in which the immune system is not able to protect the body effectively from foreign invaders such as bacteria or viruses. Starting in childhood, most people with BLS I develop recurrent bacterial infections in the lungs and airways (respiratory tract). These recurrent infections can lead to a condition called bronchiectasis, which damages the passages leading from the windpipe to the lungs (bronchi) and can cause breathing problems.","mondoId":"MONDO:0971006","records":[{"frequencyKind":"reported","key":"05ab262d2ea54252dffe22b5cf8ab726a860391c0cc98c20e15d0a3abc168a31","raw":{"aspect":"P","body_system":"respiratory","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0002097","is_excluded":false,"label":"Emphysema","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"0ac77e4ab39ef53413513cdf24f2929a2350a2430946c5e422f5a69b36919403","raw":{"aspect":"P","body_system":"respiratory","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0002110","is_excluded":false,"label":"Bronchiectasis","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"3cfe7b9cb68900a8e143ed83781800162632cb4cbc2f560d0256f277b4b88c99","raw":{"aspect":"P","body_system":"respiratory","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0011109","is_excluded":false,"label":"Chronic sinusitis","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"46312bd54ace88d72c6d9c3ec61ebc7b5b7ddc939d10f773d0f1bb7dc29540e5","raw":{"aspect":"P","body_system":"respiratory","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0002837","is_excluded":false,"label":"Recurrent bronchitis","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"7ca4a243a38f98edbef75cfafb0d80ba268ab9c171e57ca4edca448022daa2a8","raw":{"aspect":"P","body_system":"eye","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0001083","is_excluded":false,"label":"Ectopia lentis","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"a6be33f84bf44376240852d1fef48d004ee951e88592441ab8d3369dda05cef9","raw":{"aspect":"P","body_system":"skin","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0200042","is_excluded":false,"label":"Skin ulcer","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"bed2ee91e6e105687d32aabcc38de339b7588ddbbf5ab35dd0d9df99d4374800","raw":{"aspect":"P","body_system":"ear","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0000389","is_excluded":false,"label":"Chronic otitis media","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"cfd4355c32e2bee73fc21cd6411641d55cccf54242df010144e79b0707e5353f","raw":{"aspect":"P","body_system":"head_and_neck","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0100582","is_excluded":false,"label":"Nasal polyposis","onset_id":null,"reference":"OMIM:604571","source_release":"2026-06-23"},"sourceGroups":["omim"]},{"frequencyKind":"reported","key":"fc9b851b8b7c11202feda3fa603179db435a4d56ac1562e8c87345c8688a02a3","raw":{"aspect":"P","body_system":"respiratory","disease_id":"OMIM:604571","disease_name":"Bare lymphocyte syndrome, type I","evidence":"TAS","frequency_raw":null,"hpo_id":"HP:0011950","is_excluded":false,"label":"Unusual bronchiolitis","onset_id":null,"reference":"OMIM:604571","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":"BLS I is usually caused by mutations in the TAP1 or TAP2 gene. Each of these genes provides instructions for making a protein that plays a role in helping the immune system recognize and fight infections. In particular, the TAP1 and TAP2 proteins aid the function of MHC class I proteins.
The TAP1 and TAP2 proteins attach (bind) together to form a protein complex called transporter associated with antigen processing (TAP) complex. This complex, which is found in the membrane of a cell structure called the endoplasmic reticulum, moves (transports) protein fragments (peptides) from foreign invaders into the endoplasmic reticulum. There, the peptides are attached to MHC class I proteins. The peptide-bound MHC class I proteins are then moved to the surface of the cell so that specialized immune system cells can interact with them. When these immune system cells recognize the peptides as harmful, they launch an immune response to get rid of the foreign invaders.
Mutations in the TAP1 or TAP2 gene prevent formation of the TAP complex, which impairs the transport of peptides into the endoplasmic reticulum. Because there are no peptides for MHC class I proteins to bind, they are broken down, which results in a shortage of MHC class I proteins on the surface of cells. A lack of these proteins impairs the body's immune response to bacteria, leading to recurrent bacterial infections. Researchers are unsure why people with BLS I do not also get viral infections, but they suspect that other immune processes are able to recognize and fight viruses. It is also not clear how TAP1 and TAP2 gene mutations are involved in the development of skin ulcers.
Mutations in another gene involved in the attachment of peptides to MHC class I proteins very rarely cause BLS I.
","key":"forms","title":"What causes Bare lymphocyte syndrome type I?"},{"bodyHtml":"Many people with BLS I also have open sores (ulcers) on their skin, usually on the face, arms, and legs. These ulcers typically develop in adolescence or young adulthood. Some people with BLS I have no symptoms of the condition.
People with BLS I have a shortage of specialized immune proteins called major histocompatibility complex (MHC) class I proteins on cells, including infection-fighting white blood cells (lymphocytes), which is where the condition got its name.
Source: MedlinePlus Genetics
","key":"overview","title":"Condition overview"}],"sharedSources":[],"slug":"bare-lymphocyte-syndrome-type-i","sourceDocuments":[{"name":"Bare lymphocyte syndrome type I","reviewed":"2017-08","sections":{"causes":{"fetchedAt":"2026-10-20T20:19:45.466586+00:00","label":"Causes","pageSha256":"8bcd0255d039b9a1ef133b9c10dc659076bd0b95ea6303f7f8b47881c78a2dcb","sourceUrl":"https://medlineplus.gov/genetics/condition/bare-lymphocyte-syndrome-type-i/#causes","status":"available"}},"source_release":"2026-10-01","url":"https://medlineplus.gov/genetics/condition/bare-lymphocyte-syndrome-type-i"}],"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":"Bare lymphocyte syndrome type I"},"schemaVersion":1}