{"frequencyBands":{"HP:0040280":[100,100],"HP:0040281":[80,99],"HP:0040282":[30,79],"HP:0040283":[5,29],"HP:0040284":[1,4],"HP:0040285":[0,0]},"page":{"columns":[{"gene":"","key":"MONDO:0014115/OMIM:615281","label":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","mondoId":"MONDO:0014115","onsetQualifier":null,"recordKeys":["05e556d718582fec0f3008c975af905bd680dcec066712bfae7a169f394f5206","09dd86c9b56d88da6395492135f70b6604a824a5c7850a9373b7356736532174","3848b4f130c907645f06005385735b9a613d4558759baed1564e1c6ffa40daa9","510adb95f1ce34a21ea94fa0dec2e6d30c06c6f113c6e631180902302beec139","5978bf88bfab61af9c1d6fb58d4f83b71aeb5bd376c22ee177d092220cbadbd7","6bb5156929b63f2b008a618a2bee2aab6a833b590f0e3f2dd49d49f50fb646e3","711fb4e82dc902a7048771fa4e044074b2f90dc37d8d6cc98706b1f3ee18e742","770c244a59757ba6139519f397d2a6a5becb7b76615c43dc3fd527043ef955b4","932e8cb8a44a266822459fcd4be1dac1aac7f8ed2bdfd21c916bc86ed34a870d","97708f017535e3b3b74c059b3d2bd746210d1d49fe37764954b429bb54896203","a1e5315aebf8d64b2e8867e850c7713d303d41370cf63ae454a1f15737e7ad58","a998d38f5a219ee583ce19cd45570b1305fa7ec1689ff1362df5e3f37cce300d","be252cea6538531fc5cea7b4e92610f5905d6bd37ef8af6f84710e571c73f5d3","be643d8bc3a02d0f18b1c1b039323b0573d3414f27f572f29170271b20c56abe","cb37f715580e893446a00e7bd5440faf5df756b5c5f03bc1f6be3f5127633365","d5ebc24aa3cb9a3157fdf372420f0bd72d0ef824875b1ad40454bc5dd514880a","d85650533417b20a44f51bd0649c85cddb4c1e62d61345800679011cf87c7949","db58e0a662b230f6506c05675546acb302930e24bf8084aedc12845d4c39b635","fec68dcd6301770d196401e8b8dabb0c72a0eb9155e6492e29b02f45f81b04b7"],"recordQualifiers":{},"scopeLabel":"OMIM:615281","sourceIds":["OMIM:615281"],"sourceScope":"This column retains the native source entry. It is not a pooled estimate for the umbrella condition."}],"comparison":{"collapseColumnsLabel":"Show initial comparisons","defaultColumnKeys":["MONDO:0014115/OMIM:615281"],"expandColumnsLabel":"Compare all source entries","intro":"Compare the original source entries. Different entries may describe different patient groups.","primaryFeatureIds":[],"scopeNoteHtml":"<p>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.</p>"},"coverage":{"countRecords":18,"emptyColumnKeys":[],"hpoRelease":"2026-06-23","narrativeSourceChanges":[],"records":19,"sourceGroups":{"omim":0,"orphanet":0,"published":19}},"features":[{"hpoId":"HP:0001251","label":"Ataxia (coordination difficulty)","primary":false},{"hpoId":"HP:0008936","label":"Axial hypotonia","primary":false},{"hpoId":"HP:0003487","label":"Babinski sign","primary":false},{"hpoId":"HP:0001348","label":"Brisk reflexes","primary":false},{"hpoId":"HP:0010729","label":"Cherry red spot of the macula","primary":false},{"hpoId":"HP:0003429","label":"CNS hypomyelination","primary":false},{"hpoId":"HP:0001260","label":"Dysarthria","primary":false},{"hpoId":"HP:0002079","label":"Hypoplasia of the corpus callosum","primary":false},{"hpoId":"HP:0000737","label":"Irritability","primary":false},{"hpoId":"HP:0002352","label":"Leukoencephalopathy","primary":false},{"hpoId":"HP:0002061","label":"Lower limb spasticity","primary":false},{"hpoId":"HP:0001256","label":"Mild intellectual disability","primary":false},{"hpoId":"HP:0001270","label":"Motor delay","primary":false},{"hpoId":"HP:0000639","label":"Nystagmus","primary":false},{"hpoId":"HP:0000543","label":"Optic disc pallor","primary":false},{"hpoId":"HP:0001250","label":"Seizures","primary":false},{"hpoId":"HP:0001264","label":"Spastic diplegia","primary":false},{"hpoId":"HP:0003298","label":"Spina bifida occulta","primary":false},{"hpoId":"HP:0002144","label":"Tethered cord","primary":false}],"ledeHtml":"Hypomyelination with brainstem and spinal cord involvement and leg spasticity (HBSL) is a condition that affects the brain and spinal cord (central nervous system). In particular, the condition affects nerves in specific regions (called tracts) within the spinal cord and the brainstem, which is the part of the brain that connects to the spinal cord. HBSL is a form of leukodystrophy, which is a group of conditions that involve abnormalities of the nervous system&#x27;s white matter. The white matter consists of nerve fibers covered by a fatty substance, called myelin, that insulates the fibers and promotes the rapid transmission of nerve impulses. In HBSL, the nervous system has a reduced ability to form myelin (hypomyelination).","mondoId":"MONDO:0014115","records":[{"frequencyKind":"count","key":"05e556d718582fec0f3008c975af905bd680dcec066712bfae7a169f394f5206","raw":{"aspect":"P","body_system":"head_and_neck","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"1/10","hpo_id":"HP:0010729","is_excluded":false,"label":"Cherry red spot of the macula","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"09dd86c9b56d88da6395492135f70b6604a824a5c7850a9373b7356736532174","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"4/10","hpo_id":"HP:0001256","is_excluded":false,"label":"Mild intellectual disability","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"3848b4f130c907645f06005385735b9a613d4558759baed1564e1c6ffa40daa9","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"10/10","hpo_id":"HP:0002061","is_excluded":false,"label":"Lower limb spasticity","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"reported","key":"510adb95f1ce34a21ea94fa0dec2e6d30c06c6f113c6e631180902302beec139","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":null,"hpo_id":"HP:0002352","is_excluded":false,"label":"Leukoencephalopathy","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"5978bf88bfab61af9c1d6fb58d4f83b71aeb5bd376c22ee177d092220cbadbd7","raw":{"aspect":"P","body_system":"musculoskeletal","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"8/10","hpo_id":"HP:0008936","is_excluded":false,"label":"Axial hypotonia","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"6bb5156929b63f2b008a618a2bee2aab6a833b590f0e3f2dd49d49f50fb646e3","raw":{"aspect":"P","body_system":"eye","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"5/10","hpo_id":"HP:0000639","is_excluded":false,"label":"Nystagmus","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"711fb4e82dc902a7048771fa4e044074b2f90dc37d8d6cc98706b1f3ee18e742","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"1/10","hpo_id":"HP:0003298","is_excluded":false,"label":"Spina bifida occulta","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"770c244a59757ba6139519f397d2a6a5becb7b76615c43dc3fd527043ef955b4","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"3/10","hpo_id":"HP:0001270","is_excluded":false,"label":"Motor delay","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"932e8cb8a44a266822459fcd4be1dac1aac7f8ed2bdfd21c916bc86ed34a870d","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"8/10","hpo_id":"HP:0002079","is_excluded":false,"label":"Hypoplasia of the corpus callosum","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"97708f017535e3b3b74c059b3d2bd746210d1d49fe37764954b429bb54896203","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"3/10","hpo_id":"HP:0001260","is_excluded":false,"label":"Dysarthria","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"a1e5315aebf8d64b2e8867e850c7713d303d41370cf63ae454a1f15737e7ad58","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"5/9","hpo_id":"HP:0003429","is_excluded":false,"label":"CNS hypomyelination","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"a998d38f5a219ee583ce19cd45570b1305fa7ec1689ff1362df5e3f37cce300d","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"2/10","hpo_id":"HP:0000737","is_excluded":false,"label":"Irritability","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"be252cea6538531fc5cea7b4e92610f5905d6bd37ef8af6f84710e571c73f5d3","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"10/10","hpo_id":"HP:0003487","is_excluded":false,"label":"Babinski sign","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"be643d8bc3a02d0f18b1c1b039323b0573d3414f27f572f29170271b20c56abe","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"2/10","hpo_id":"HP:0001250","is_excluded":false,"label":"Seizure","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"cb37f715580e893446a00e7bd5440faf5df756b5c5f03bc1f6be3f5127633365","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"3/10","hpo_id":"HP:0001264","is_excluded":false,"label":"Spastic diplegia","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"d5ebc24aa3cb9a3157fdf372420f0bd72d0ef824875b1ad40454bc5dd514880a","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"10/10","hpo_id":"HP:0001348","is_excluded":false,"label":"Brisk reflexes","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"d85650533417b20a44f51bd0649c85cddb4c1e62d61345800679011cf87c7949","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"1/10","hpo_id":"HP:0002144","is_excluded":false,"label":"Tethered cord","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"db58e0a662b230f6506c05675546acb302930e24bf8084aedc12845d4c39b635","raw":{"aspect":"P","body_system":"nervous_system","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"IEA","frequency_raw":"4/9","hpo_id":"HP:0001251","is_excluded":false,"label":"Ataxia","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]},{"frequencyKind":"count","key":"fec68dcd6301770d196401e8b8dabb0c72a0eb9155e6492e29b02f45f81b04b7","raw":{"aspect":"P","body_system":"eye","disease_id":"OMIM:615281","disease_name":"Hypomyelination with brainstem and spinal cord involvement and legspasticity","evidence":"PCS","frequency_raw":"3/10","hpo_id":"HP:0000543","is_excluded":false,"label":"Optic disc pallor","onset_id":null,"reference":"PMID:23643384","source_release":"2026-06-23"},"sourceGroups":["published"]}],"referenceLabels":{},"references":{"causeHtml":"<ul><li><a href=\"https://medlineplus.gov/genetics/condition/hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity\">Hypomyelination with brainstem and spinal cord involvement and leg spasticity</a></li></ul>","identityNote":"MONDO cross-references identify native condition entries. Ancestor membership does not transfer phenotype values between groups.","importantHtml":""},"sections":[{"bodyHtml":"<p>HBSL is caused by mutations in a gene called DARS1, which provides instructions for making an enzyme called aspartyl-tRNA synthetase. This enzyme is important in the production (synthesis) of proteins.</p><p>During protein synthesis, building blocks (amino acids) are connected together in a specific order, creating a chain of amino acids that forms the protein. Aspartyl-tRNA synthetase plays a role in adding the amino acid aspartate at the proper place in proteins.</p><p>Mutations in the DARS1 gene result in decreased aspartyl-tRNA synthetase enzyme activity, which hinders the addition of aspartate to proteins. It is unclear how the DARS1 gene mutations lead to the signs and symptoms of HBSL. Researchers do not understand why reduced activity of aspartyl-tRNA synthetase affects myelination or why specific parts of the brainstem and spinal cord are involved.</p><p class=\"section-source\"><a href=\"https://medlineplus.gov/genetics/condition/hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity/#causes\">MedlinePlus Genetics: Causes</a></p>","key":"forms","title":"What causes Hypomyelination with brainstem and spinal cord involvement and leg spasticity?"},{"bodyHtml":"<p>In HBSL, early development of motor skills (such as rolling over and sitting) may be normal, but movement problems typically begin within the infant&#x27;s first year. However, in some individuals, these problems do not appear until adolescence. The characteristic feature of HBSL is muscle stiffness (spasticity) in the legs that worsens over time. Most people with HBSL are unable to walk independently. Other neurological problems in affected individuals can include abnormal side-to-side movements of the eyes (nystagmus), weak muscle tone (hypotonia) in the torso, and mild intellectual disability.</p><p>Distinct changes in the brains of people with HBSL can be seen using magnetic resonance imaging (MRI). These characteristic abnormalities typically involve specific regions (called tracts) within the brainstem and spinal cord, especially the pyramidal tract, lateral corticospinal tract, and the dorsal column.</p><p class=\"section-source\">Source: <a href=\"https://medlineplus.gov/genetics/condition/hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity\">MedlinePlus Genetics</a></p>","key":"overview","title":"Condition overview"}],"sharedSources":[],"slug":"hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity","sourceDocuments":[{"name":"Hypomyelination with brainstem and spinal cord involvement and leg spasticity","reviewed":"2019-02","sections":{"causes":{"fetchedAt":"2026-10-20T20:22:23.161367+00:00","label":"Causes","pageSha256":"78fbd72a7178207357840aef937c48a68d6936f7c3c98f14ea6632213118e7c4","sourceUrl":"https://medlineplus.gov/genetics/condition/hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity/#causes","status":"available"}},"source_release":"2026-10-01","url":"https://medlineplus.gov/genetics/condition/hypomyelination-with-brainstem-and-spinal-cord-involvement-and-leg-spasticity"}],"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":"Hypomyelination with brainstem and spinal cord involvement and leg spasticity"},"schemaVersion":1}