{"Name":"Hypomyelinating leukodystrophy 6","DiseaseID__c":"GARD:0010917","id":10917,"encodedName":"hypomyelinating-leukodystrophy-6","IsDeleted":false,"Disease_Name_Full__c":"Hypomyelinating leukodystrophy 6","Xref_IDs__c":"C183310; C2676244; C567314; DOID:0060798; MEDGEN:436642; MONDO:0012905; OMIM:612438; ORPHA:139441","USA_Estimate__c":"1,000","No_of_Specialist_Tagsa__c":3,"No_of_ClinGen_records__c":0,"No_of_GeneReviews__c":0,"No_of_HHS_records__c":1,"World_Estimate__c":"1 to 8,000","No_of_HRSA_records__c":0,"Evidence_Based_Score__c":1,"No_of_Disease_Descriptions__c":5,"Disease_Characteristics_Score__c":8,"No_of_Age_at_Onset__c":3,"Description_Source__c":"MONDO:0012905","Disease_Description__c":"A rare disorder characterized by slowly progressive spasticity, extrapyramidal movement disorders (dystonia, choreoathetosis and rigidity), cerebellar ataxia, moderate to severe cognitive deficit, and anarthria/dysarthria.","GARD_Name__c":"Hypomyelinating leukodystrophy 6","GARD_Synonym__c":"h-abc; h-abc - hypomyelination, atrophy of basal ganglia and cerebellum; habc; hld6; hypomyelinating leukodystrophy type 6; hypomyelinating leukodystrophy with atrophy of basal ganglia and cerebellum; hypomyelinating leukodystrophy with atrophy of the basal ganglia and cerebellum; hypomyelination with atrophy of basal ganglia and cerebellum; hypomyelination with atrophy of basal ganglia and cerebellum syndrome; leukodystrophy, hypomyelinating, type 6; leukodystrophy, hypomyelinating, with atrophy of the basal ganglia and cerebellum; tubb4a-associated leukodystrophy","Curated_Disease_Description_Source__c":"GARD:0010917","Curated_Disease_Description__c":"TUBB4A-related leukodystrophy is a disorder that affects the nervous system. Leukodystrophies are conditions that involve abnormalities of the nervous systems white matter, which consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve fibers and promotes the rapid transmission of nerve impulses. In particular, TUBB4A-related leukodystrophy involves hypomyelination, which means that the nervous system has a reduced ability to form myelin. In some affected individuals, myelin may also break down, which is known as demyelination. People with TUBB4A-related leukodystrophy have different combinations of signs and symptoms. Some of these combinations are described as separate disorders. However, the features in some affected individuals do not fit into these defined disorders. Researchers now group all of these cases of leukodystrophy, which have the same genetic cause, as TUBB4A-related leukodystrophy. At the most severe end of the TUBB4A-related leukodystrophy spectrum is a condition called hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). This disorder begins in infancy or early childhood. Most affected individuals have delayed development of motor skills, such as sitting and walking, and some are never able to walk on their own. In other cases, motor skills develop normally and then are lost in early childhood (developmental regression). In addition, individuals with H-ABC have other movement abnormalities, such as involuntary muscle contractions (dystonia), uncontrolled movements of the limbs (choreoathetosis), muscle stiffness (rigidity), and difficulty coordinating movements (ataxia). These individuals also often have impaired speech (dysarthria), a weak voice (dysphonia), and swallowing problems (dysphagia). Some develop seizures. Learning difficulty is common in individuals with H-ABC. H-ABC is characterized by particular brain abnormalities, including hypomyelination. In addition, tissue in certain regions of the brain breaks down (atrophies), most prominently in a region called the putamen, which is part of a group of structures that help control movement (the basal ganglia). Atrophy of brain tissue in another region involved in movement called the cerebellum is common, and atrophy of the cerebrum, which controls most voluntary activity, language, sensory perception, learning, and memory, can also occur. At the mildest end of the TUBB4A-related leukodystrophy spectrum is a condition called isolated hypomyelination, which begins at any time from late childhood to adulthood. Individuals at this end of the spectrum have mild hypomyelination and sometimes mild atrophy of the cerebellum, but no problems with the basal ganglia. These individuals can have movement problems, dysarthria, and learning difficulty, although these features are typically milder than in H-ABC. The features in other individuals with TUBB4A-related leukodystrophy fall in between these two extremes. Affected individuals can have varying degrees of hypomyelination and atrophy or impairment of the basal ganglia or other brain regions. Movement problems can also occur. A small group of affected individuals develop muscle stiffness and paralysis of the lower limbs (spastic paraplegia) that slowly worsen. In addition, these individuals may have mild hypomyelination and ataxia without the other movement or learning problems common in H-ABC.","Curated_USA_Estimate_Source__c":null,"Curated_USA_Estimate__c":"1,000","Age_at_Onset_Snippet_Text__c":"from Birth to Childhood","SourceID__c":"ORPHA:139441","Deprecated__c":"No","Disease_Concept_Type__c":"Rare Disease Entity","MONDO_ID__c":"MONDO:0012905","ORPHANET_ID__c":"ORPHA:139441","Replaced_By_ID__c":null,"Display_Spanish_Disease_Name__c":"Hipomielinización con atrofia de los ganglios basales y del cerebelo","Spanish_Description_Source__c":"ORPHA:139441","Spanish_Description__c":"Es un trastorno poco frecuente caracterizado por espasticidad lentamente progresiva, trastornos extrapiramidales del movimiento (distonía, coreoatetosis y rigidez), ataxia cerebelosa, déficit cognitivo de moderado a grave, y anartria/disartria.","Spanish_Disease_Name__c":"hipomielinización con atrofia de los ganglios basales y del cerebelo","Spanish_GARD_Synonym__c":"h-abc","Category_Linearization__c":"ORPHA:98006","icd10_id__c":null,"mesh_id__c":null,"omim_id__c":null,"snomed_id__c":null,"umls_id__c":null,"GARD_Disease__c":[{"Curated_Disease_Description__c":"TUBB4A-related leukodystrophy is a disorder that affects the nervous system. Leukodystrophies are conditions that involve abnormalities of the nervous systems white matter, which consists of nerve fibers covered by a fatty substance called myelin. Myelin insulates nerve fibers and promotes the rapid transmission of nerve impulses. In particular, TUBB4A-related leukodystrophy involves hypomyelination, which means that the nervous system has a reduced ability to form myelin. In some affected individuals, myelin may also break down, which is known as demyelination. People with TUBB4A-related leukodystrophy have different combinations of signs and symptoms. Some of these combinations are described as separate disorders. However, the features in some affected individuals do not fit into these defined disorders. Researchers now group all of these cases of leukodystrophy, which have the same genetic cause, as TUBB4A-related leukodystrophy. At the most severe end of the TUBB4A-related leukodystrophy spectrum is a condition called hypomyelination with atrophy of the basal ganglia and cerebellum (H-ABC). This disorder begins in infancy or early childhood. Most affected individuals have delayed development of motor skills, such as sitting and walking, and some are never able to walk on their own. In other cases, motor skills develop normally and then are lost in early childhood (developmental regression). In addition, individuals with H-ABC have other movement abnormalities, such as involuntary muscle contractions (dystonia), uncontrolled movements of the limbs (choreoathetosis), muscle stiffness (rigidity), and difficulty coordinating movements (ataxia). These individuals also often have impaired speech (dysarthria), a weak voice (dysphonia), and swallowing problems (dysphagia). Some develop seizures. Learning difficulty is common in individuals with H-ABC. H-ABC is characterized by particular brain abnormalities, including hypomyelination. In addition, tissue in certain regions of the brain breaks down (atrophies), most prominently in a region called the putamen, which is part of a group of structures that help control movement (the basal ganglia). Atrophy of brain tissue in another region involved in movement called the cerebellum is common, and atrophy of the cerebrum, which controls most voluntary activity, language, sensory perception, learning, and memory, can also occur. At the mildest end of the TUBB4A-related leukodystrophy spectrum is a condition called isolated hypomyelination, which begins at any time from late childhood to adulthood. Individuals at this end of the spectrum have mild hypomyelination and sometimes mild atrophy of the cerebellum, but no problems with the basal ganglia. These individuals can have movement problems, dysarthria, and learning difficulty, although these features are typically milder than in H-ABC. The features in other individuals with TUBB4A-related leukodystrophy fall in between these two extremes. Affected individuals can have varying degrees of hypomyelination and atrophy or impairment of the basal ganglia or other brain regions. Movement problems can also occur. A small group of affected individuals develop muscle stiffness and paralysis of the lower limbs (spastic paraplegia) that slowly worsen. In addition, these individuals may have mild hypomyelination and ataxia without the other movement or learning problems common in H-ABC.","Curated_Disease_Description_Source__c":"GARD:0010917","GARD_Synonym__c":"h-abc; h-abc - hypomyelination, atrophy of basal ganglia and cerebellum; habc; hld6; hypomyelinating leukodystrophy type 6; hypomyelinating leukodystrophy with atrophy of basal ganglia and cerebellum; hypomyelinating leukodystrophy with atrophy of the basal ganglia and cerebellum; hypomyelination with atrophy of basal ganglia and cerebellum; hypomyelination with atrophy of basal ganglia and cerebellum syndrome; leukodystrophy, hypomyelinating, type 6; leukodystrophy, hypomyelinating, with atrophy of the basal ganglia and cerebellum; tubb4a-associated leukodystrophy","Name":"Hypomyelinating leukodystrophy 6","Curated_USA_Estimate__c":"1,000","estimateUsa":"1,000"}],"Organization_Supported_Diseases__c":[{"Account_Name__c":"H-ABC Foundation UK","Website__c":"https://www.habcfoundationuk.co.uk/"},{"Account_Name__c":"Childhood Dementia Initiative","Website__c":"https://www.childhooddementia.org/"},{"Account_Name__c":"A Rare Ruby","Website__c":"https://www.facebook.com/RarestRuby/"},{"Account_Name__c":"Kinslow TUBB4A Foundation","Website__c":"https://www.facebook.com/p/Kinslow-tubb4a-Foundation-61552524513547/"},{"Account_Name__c":"The Myelin Project","Website__c":"http://www.myelin.org"},{"Account_Name__c":"Alex The Leukodystrophy Charity","Website__c":"https://www.alextlc.org"},{"Account_Name__c":"Foundation to Fight H-ABC","Website__c":"https://www.h-abc.org/"},{"Account_Name__c":"Hunter's Hope Foundation","Website__c":"https://www.huntershope.org/"}],"GARD_Disease_Tag__c":[{"Tag_Name__c":"Genetics","Tag_Category__c":"Cause;Disease Category;Specialist","category_description":"Genetic diseases affect the DNA, or genetic instructions, which directs how tissues, organs, and body systems function.","curated_tag_name":"Genetic diseases"},{"Tag_Name__c":"Neurology","Tag_Category__c":"Disease Category;Specialist","category_description":"Neurological diseases affect the brain, spinal cord, cranial nerves, autonomic nerves, or other peripheral nerves.","curated_tag_name":"Neurological diseases"},{"Tag_Name__c":"Leukodystrophy","Tag_Category__c":"Account;Cause;Disease Category","category_description":"Leukodystrophies are a group of genetic neurological diseases that affect the white matter of the brain and spinal cord.","curated_tag_name":"Leukodystrophies"},{"Tag_Name__c":"Pediatrics","Tag_Category__c":"Specialist"}],"Age_At_Onset__c":[{"Age_At_Onset__c":"Infancy","Provided_By__c":"ORPHA:139441"},{"Age_At_Onset__c":"Childhood","Provided_By__c":"ORPHA:139441"},{"Age_At_Onset__c":"Neonatal","Provided_By__c":"ORPHA:139441"}],"Diagnosis__c":[{"Type__c":"GTR","Curie__c":"MEDGEN:C2676244"}],"External_Identifier_Disease__c":[{"URL__c":"https://raresource.nih.gov/diseases/filter/0010917","Source__c":"RareSource"},{"URL__c":"https://www.ncbi.nlm.nih.gov/mesh/C567314","Source__c":"MONDO:0012905","Xref__c":"C567314"},{"URL__c":"https://www.orpha.net/en/disease/detail/139441","Source__c":"C2676244; MONDO:0012905","Xref__c":"ORPHA:139441"},{"URL__c":"https://uts.nlm.nih.gov/uts/umls/concept/C2676244","Source__c":"C2676244","Xref__c":"C2676244"},{"URL__c":"https://www.ebi.ac.uk/ols4/ontologies/doid/classes?obo_id=DOID%3A0060798","Source__c":"MONDO:0012905","Xref__c":"DOID:0060798"},{"URL__c":"https://www.omim.org/entry/612438","Source__c":"C2676244; MONDO:0012905","Xref__c":"OMIM:612438"},{"URL__c":"https://www.ncbi.nlm.nih.gov/medgen/?term=436642","Source__c":"C2676244","Xref__c":"MEDGEN:436642"},{"URL__c":"https://evsexplore.semantics.cancer.gov/evsexplore/concept/ncit/C183310","Source__c":"C2676244","Xref__c":"C183310"},{"URL__c":"http://purl.obolibrary.org/obo/MONDO_0012905","Source__c":"GARD:0010917","Xref__c":"MONDO:0012905"},{"URL__c":"https://browser.ihtsdotools.org/?perspective=full&conceptId1=724283004","Source__c":"C2676244","Xref__c":"724283004"},{"URL__c":"https://www.ncbi.nlm.nih.gov/books/NBK395611","Source__c":"Gene Review","Xref__c":"NBK395611"},{"URL__c":"https://www.h-abc.org/blog/2022/6/6/iebb843iq8b5dfzb0k7l60fnenwr5g"}],"GARD_Disease_Gene__c":[{"GeneSymbol__c":"TUBB4A","GHR_URL__c":"https://medlineplus.gov/genetics/gene/tubb4a","Gene_Type__c":"protein-coding gene","Causal_Gene__c":true}],"Inheritance__c":["Autosomal dominant","Autosomal recessive"],"GARD_Disease_Feature__c":[{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"The term intellectual disability or intellectual developmental disorder is used to describe significantly sub-average intellectual and adaptive functioning based on clinical assessment and as measured by individually administered, appropriately normed, standardized and validated tests of intellectual functioning and adaptive behavior, with onset during the developmental period from infancy through adolescence.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001249","HPO_Synonym__c":"Intellectual disability; Mental deficiency; Mental retardation; Mental retardation, nonspecific; Mental-retardation; Nonprogressive intellectual disability; Nonprogressive mental retardation","HPO_Name__c":"Intellectual disability","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Involuntary movements characterized by both athetosis (inability to sustain muscles in a fixed position) and chorea (widespread jerky arrhythmic movements).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001266","HPO_Synonym__c":"Choreoathetoid movements","HPO_Name__c":"Choreoathetosis","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Dysarthric speech is a general description referring to a neurological speech disorder characterized by poor articulation. Depending on the involved neurological structures, dysarthria may be further classified as spastic, flaccid, ataxic, hyperkinetic and hypokinetic, or mixed.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001260","HPO_Synonym__c":"Difficulty articulating speech; Dysarthric speech","HPO_Name__c":"Dysarthria","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Reduced amount of myelin in the nervous system resulting from defective myelinogenesis in the white matter of the central nervous system.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0006808","HPO_Synonym__c":"Hypomyelination of the brain","HPO_Name__c":"Cerebral hypomyelination","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Cerebellar atrophy is defined as a cerebellum with initially normal structures, in a posterior fossa with normal size, which displays enlarged fissures (interfolial spaces) in comparison to the foliae secondary to loss of tissue. Cerebellar atrophy implies irreversible loss of tissue and result from an ongoing progressive disease until a final stage is reached or a single injury, e.g. an intoxication or infectious event.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001272","HPO_Synonym__c":"Atrophic cerebellum; Degeneration of cerebellum","HPO_Name__c":"Cerebellar atrophy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"A degree of language development that is significantly below the norm for a child of a specified age.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000750","HPO_Synonym__c":"Deficiency of speech development; Delayed language development; Delayed speech; Delayed speech acquisition; Delayed speech and language development; Delayed speech development; Impaired speech and language development; Impaired speech development; Language delay; Language delayed; Language development deficit; Late-onset speech development; Poor language development; Speech and language delay; Speech and language difficulties; Speech delay","HPO_Name__c":"Delayed speech and language development","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Hypotonia is an abnormally low muscle tone (the amount of tension or resistance to movement in a muscle). Even when relaxed, muscles have a continuous and passive partial contraction which provides some resistance to passive stretching. Hypotonia thus manifests as diminished resistance to passive stretching. Hypotonia is not the same as muscle weakness, although the two conditions can co-exist.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001252","HPO_Synonym__c":"Low muscle tone; Low or weak muscle tone; Muscle hypotonia; Muscular hypotonia","HPO_Name__c":"Hypotonia","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Impairment of certain skills such as reading or writing, coordination, self-control, or attention that interfere with the ability to learn. The impairment is not related to a global deficiency of intelligence.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001328","HPO_Name__c":"Specific learning disability","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Continuous involuntary sustained muscle contraction. When an affected muscle is passively stretched, the degree of resistance remains constant regardless of the rate at which the muscle is stretched. This feature helps to distinguish rigidity from muscle spasticity.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002063","HPO_Synonym__c":"Muscle rigidity; Rigidity","HPO_Name__c":"Rigidity","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A seizure is an intermittent abnormality of nervous system physiology characterized by a transient occurrence of signs and/or symptoms due to abnormal excessive or synchronous neuronal activity in the brain.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001250","HPO_Synonym__c":"Epileptic seizure; Seizures","HPO_Name__c":"Seizure","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000505","HPO_Synonym__c":"Impaired vision; Loss of eyesight; Poor vision; Visual impairment","HPO_Name__c":"Visual impairment","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Muscular hypotonia (abnormally low muscle tone) affecting the musculature of the trunk.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0008936","HPO_Synonym__c":"Low muscle tone in trunk; Muscular hypotonia of the trunk; Truncal hypotonia","HPO_Name__c":"Axial hypotonia","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A motor disorder characterized by a velocity-dependent increase in tonic stretch reflexes with increased muscle tone, exaggerated (hyperexcitable) tendon reflexes.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001257","HPO_Synonym__c":"Involuntary muscle stiffness, contraction, or spasm; Muscle spasticity; Muscular spasticity","HPO_Name__c":"Spasticity","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Ataxia refers to impaired coordination of voluntary muscle movement. Cerebellar ataxia refers to ataxia due to dysfunction of the cerebellum. This causes a variety of elementary neurological deficits including asynergy (lack of coordination between muscles, limbs and joints), dysmetria (lack of ability to judge distances that can lead to under- or overshoot in grasping movements), and dysdiadochokinesia (inability to perform rapid movements requiring antagonizing muscle groups to be switched on and off repeatedly).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001251","HPO_Synonym__c":"Cerebellar ataxia","HPO_Name__c":"Ataxia","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Rhythmic, involuntary oscillations of one or both eyes related to abnormality in fixation, conjugate gaze, or vestibular mechanisms.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000639","HPO_Synonym__c":"Involuntary, rapid, rhythmic eye movements","HPO_Name__c":"Nystagmus","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Leukodystrophy refers to deterioration of white matter of the brain resulting from degeneration of myelin sheaths in the CNS. Their basic defect is directly related to the synthesis and maintenance of myelin membranes. Symmetric white matter involvement at MRI is a typical finding in patients with leukodystrophies.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002415","HPO_Synonym__c":"Degeneration of white matter of brain","HPO_Name__c":"Leukodystrophy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Ocular motor apraxia is a deficiency in voluntary, horizontal, lateral, fast eye movements (saccades) with retention of slow pursuit movements. The inability to follow objects visually is often compensated by head movements. There may be decreased smooth pursuit, and cancelation of the vestibulo-ocular reflex.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000657","HPO_Synonym__c":"Ocular motor apraxia","HPO_Name__c":"Oculomotor apraxia","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"An unintentional, oscillating to-and-fro muscle movement about a joint axis.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001337","HPO_Synonym__c":"Tremor; Tremors","HPO_Name__c":"Tremor","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Head circumference below 2 standard deviations below the mean for age and sex.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000252","HPO_Synonym__c":"Abnormally small cranium; Abnormally small skull; Decreased circumference of cranium; Decreased size of cranium; Decreased size of skull; Reduced head circumference; small cranium; Small head circumference","HPO_Name__c":"Microcephaly","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"Atrophy of the optic nerve. Optic atrophy results from the death of the retinal ganglion cell axons that comprise the optic nerve and manifesting as a pale optic nerve on fundoscopy.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000648","HPO_Synonym__c":"Optic nerve atrophy; Optic-nerve degeneration","HPO_Name__c":"Optic atrophy","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"A type of Developmental delay characterized by a delay in acquiring motor skills.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001270","HPO_Synonym__c":"Delay in development of motor milestones; Delay in motor development; Delayed development of motor milestones; Delayed early motor milestones; Delayed motor development; Delayed motor milestones; Locomotor delay; Motor developmental delay; Motor developmental milestones not achieved; Motor retardation; Retarded motor development; Slow development of motor milestones","HPO_Name__c":"Motor delay","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Saccadic undershoot, i.e., a saccadic eye movement that has less than the magnitude that would be required to gain fixation of the object.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000571","HPO_Name__c":"Hypometric saccades","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Loss of developmental skills, as manifested by loss of developmental milestones.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002376","HPO_Synonym__c":"Loss of acquired milestones; Loss of developmental milestones; Loss of milestones; Mental deterioration in childhood; Neurodevelopmental regression; Psychomotor regression; Psychomotor regression beginning in infancy; Psychomotor regression in infants; Psychomotor regression, progressive","HPO_Name__c":"Developmental regression","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Description__c":"A height below that which is expected according to age and sex norms. Although there is no universally accepted definition of short stature, many refer to \\\"short stature\\\" as height more than 2 standard deviations below the mean for age and sex (or below the 3rd percentile for age and sex dependent norms).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0004322","HPO_Synonym__c":"Decreased body height; Height less than 3rd percentile; Short stature; Small stature; Stature below 3rd percentile","HPO_Name__c":"Short stature","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","Feature__r":{"HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002465","HPO_Synonym__c":"Poor speech","HPO_Name__c":"Poor speech","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:612438","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An abnormally increased muscular tone that causes fixed abnormal postures. There is a slow, intermittent twisting motion that leads to exaggerated turning and posture of the extremities and trunk.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001332","HPO_Synonym__c":"Dystonic movements","HPO_Name__c":"Dystonia","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}}],"tags":{"Cause":["Genetics","Leukodystrophy"],"Disease Category":["Genetics","Neurology","Leukodystrophy"],"Specialist":["Genetics","Neurology","Pediatrics"],"Account":["Leukodystrophy"]},"synonyms":["h-abc"," h-abc - hypomyelination, atrophy of basal ganglia and cerebellum"," habc"," hld6"," hypomyelinating leukodystrophy type 6"," hypomyelinating leukodystrophy with atrophy of basal ganglia and cerebellum"," hypomyelinating leukodystrophy with atrophy of the basal ganglia and cerebellum"," hypomyelination with atrophy of basal ganglia and cerebellum"," hypomyelination with atrophy of basal ganglia and cerebellum syndrome"," leukodystrophy, hypomyelinating, type 6"," leukodystrophy, hypomyelinating, with atrophy of the basal ganglia and cerebellum"," tubb4a-associated leukodystrophy"]}