{"Name":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency","DiseaseID__c":"GARD:0002734","id":2734,"encodedName":"homocystinuria-due-to-methylene-tetrahydrofolate-reductase-deficiency","IsDeleted":false,"Disease_Name_Full__c":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency","Xref_IDs__c":"41797007; C1856061; C537357; MEDGEN:343470; MONDO:0009353; OMIM:236250; ORPHA:395","USA_Estimate__c":null,"No_of_Specialist_Tagsa__c":5,"No_of_ClinGen_records__c":0,"No_of_GeneReviews__c":0,"No_of_HHS_records__c":0,"World_Estimate__c":null,"No_of_HRSA_records__c":0,"Evidence_Based_Score__c":0,"No_of_Disease_Descriptions__c":4,"Disease_Characteristics_Score__c":8,"No_of_Age_at_Onset__c":2,"Description_Source__c":"MONDO:0009353","Disease_Description__c":"Homocystinuria due to methylene tetrahydrofolate reductase (MTHFR) deficiency is a metabolic disorder characterised by neurological manifestations.","GARD_Name__c":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency","GARD_Synonym__c":"homocysteinuria due to mthfr deficiency; homocystinuria due to deficiency of n(5,10)-methylenetetrahydrofolate reductase activity; homocystinuria due to mthfr deficiency; methylene tetrahydrofolate reductase deficiency; mthfr deficiency","Curated_Disease_Description_Source__c":"GARD:0002734","Curated_Disease_Description__c":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency (MTHFR deficiency) is a genetic condition that results from poor metabolism of folate (also called vitamin B9), due to a lack of working enzyme called MTHFR. The gene that tells our body how to make the enzyme is also called MTHFR. At least 40 rare MTHFR gene variants have been found in people with decreased or no working enzyme. Very common gene variants (C677T and A1298C) can cause some decrease in enzyme function. People with Homocystinuria due to MTHFR deficiency tend to have two rare variants or sometimes a rare variant and a common variant. Very rarely people inherit a combination of three or four common variants from their parents (for example two C677T variants and two A1298C variants) and may also develop very high levels of homocystine in their body. Homocystinuria usually does not show symptoms in a newborn baby. Symptoms may include abnormal clotting, developmental delay, seizures, intellectual disability, and microcephaly. Severe homocystinuria can also be caused by gene variants in other genes besides MTHFR.","Curated_USA_Estimate_Source__c":null,"Curated_USA_Estimate__c":null,"Age_at_Onset_Snippet_Text__c":"as a Newborn and as an Infant","SourceID__c":"ORPHA:395","Deprecated__c":"No","Disease_Concept_Type__c":"Rare Disease Entity","MONDO_ID__c":"MONDO:0009353","ORPHANET_ID__c":"ORPHA:395","Replaced_By_ID__c":null,"Display_Spanish_Disease_Name__c":"Homocistinuria por deficiencia de metilentetrahidrofolato reductasa","Spanish_Description_Source__c":"ORPHA:395","Spanish_Description__c":"La homocistinuria por deficiencia de metilentetrahidrofolato reductasa (MTHFR) es una enfermedad metabólica caracterizada por una afectación neurológica.","Spanish_Disease_Name__c":"homocistinuria por deficiencia de metilentetrahidrofolato reductasa","Spanish_GARD_Synonym__c":null,"Category_Linearization__c":"ORPHA:68367","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":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency (MTHFR deficiency) is a genetic condition that results from poor metabolism of folate (also called vitamin B9), due to a lack of working enzyme called MTHFR. The gene that tells our body how to make the enzyme is also called MTHFR. At least 40 rare MTHFR gene variants have been found in people with decreased or no working enzyme. Very common gene variants (C677T and A1298C) can cause some decrease in enzyme function. People with Homocystinuria due to MTHFR deficiency tend to have two rare variants or sometimes a rare variant and a common variant. Very rarely people inherit a combination of three or four common variants from their parents (for example two C677T variants and two A1298C variants) and may also develop very high levels of homocystine in their body. Homocystinuria usually does not show symptoms in a newborn baby. Symptoms may include abnormal clotting, developmental delay, seizures, intellectual disability, and microcephaly. Severe homocystinuria can also be caused by gene variants in other genes besides MTHFR.","Curated_Disease_Description_Source__c":"GARD:0002734","GARD_Synonym__c":"homocysteinuria due to mthfr deficiency; homocystinuria due to deficiency of n(5,10)-methylenetetrahydrofolate reductase activity; homocystinuria due to mthfr deficiency; methylene tetrahydrofolate reductase deficiency; mthfr deficiency","Name":"Homocystinuria due to methylene tetrahydrofolate reductase deficiency","estimateUsa":""}],"Organization_Supported_Diseases__c":[{"Account_Name__c":"Metabolic Support UK","Website__c":"https://www.metabolicsupportuk.org"},{"Account_Name__c":"National Blood Clot Alliance","Website__c":"https://www.stoptheclot.org/"},{"Account_Name__c":"HCU Network America","Website__c":"https://hcunetworkamerica.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":"Inborn Errors of Metabolism","Tag_Category__c":"Cause;Disease Category","category_description":"Inherited metabolic diseases, or inborn errors of metabolism, are a group of genetic diseases that affect the ability of the body's cells to convert food into energy.","curated_tag_name":"Inherited metabolic diseases"},{"Tag_Name__c":"Peripheral Neuropathy","Tag_Category__c":"Account","curated_tag_name":"Peripheral neuropathy"},{"Tag_Name__c":"Epilepsy","Tag_Category__c":"Account;Specialist","curated_tag_name":"Epilepsy"},{"Tag_Name__c":"Neuromuscular medicine","Tag_Category__c":"Specialist","curated_tag_name":"Neuromuscular medicine"},{"Tag_Name__c":"Pediatrics","Tag_Category__c":"Specialist"}],"Age_At_Onset__c":[{"Age_At_Onset__c":"Infancy","Provided_By__c":"ORPHA:395"},{"Age_At_Onset__c":"Neonatal","Provided_By__c":"ORPHA:395"}],"Diagnosis__c":[{"Type__c":"NEWBORN","Category__c":"Other","Curie__c":"http://newbornscreeningcodes.nlm.nih.gov/nb/sc/condition/MTHFR"}],"External_Identifier_Disease__c":[{"URL__c":"https://raresource.nih.gov/diseases/filter/0002734","Source__c":"RareSource"},{"URL__c":"https://www.orpha.net/en/disease/detail/395","Source__c":"C1856061; MONDO:0009353; ORPHA:395","Xref__c":"ORPHA:395"},{"URL__c":"https://browser.ihtsdotools.org/?perspective=full&conceptId1=41797007","Source__c":"MONDO:0009353","Xref__c":"41797007"},{"URL__c":"https://www.ncbi.nlm.nih.gov/medgen/?term=343470","Source__c":"C1856061","Xref__c":"MEDGEN:343470"},{"URL__c":"https://uts.nlm.nih.gov/uts/umls/concept/C1856061","Source__c":"C1856061","Xref__c":"C1856061"},{"URL__c":"https://www.omim.org/entry/236250","Source__c":"C1856061; MONDO:0009353; ORPHA:395","Xref__c":"OMIM:236250"},{"URL__c":"https://www.ncbi.nlm.nih.gov/mesh/C537357","Source__c":"MONDO:0009353","Xref__c":"C537357"},{"URL__c":"http://purl.obolibrary.org/obo/MONDO_0009353","Source__c":"GARD:0002734","Xref__c":"MONDO:0009353"},{"URL__c":"https://www.ncbi.nlm.nih.gov/books/NBK615089","Source__c":"Gene Review","Xref__c":"NBK615089"}],"GARD_Disease_Gene__c":[{"GeneSymbol__c":"MTHFR","GHR_URL__c":"https://medlineplus.gov/genetics/gene/mthfr","Gene_Type__c":"protein-coding gene","Causal_Gene__c":true}],"Inheritance__c":["Autosomal recessive"],"GARD_Disease_Feature__c":[{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Abnormal cognition is characterized by deficits in thinking, reasoning, or remembering.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0100543","HPO_Synonym__c":"Abnormality of cognition; Cognitive abnormality; Cognitive defects; Cognitive deficits; Cognitive impairment; Intellectual impairment","HPO_Name__c":"Cognitive impairment","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","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":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Partial loss of the ability to move the lower limbs accompanied by spasticity of the lower limbs.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002313","HPO_Name__c":"Spastic paraparesis","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"An anomaly of metabolism or structure of the brain identified by imaging.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0410263","HPO_Synonym__c":"Abnormal brain imaging","HPO_Name__c":"Brain imaging abnormality","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"Encephalopathy is a term that means brain disease, damage, or malfunction. In general, encephalopathy is manifested by an altered mental state.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001298","HPO_Name__c":"Encephalopathy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A functional anomaly of the upper motor neuron. The upper motor neurons are neurons of the primary motor cortex which project to the brainstem and spinal chord via the corticonuclear, corticobulbar and corticospinal (pyramidal) tracts. They are involved in control of voluntary movements. Dysfunction leads to weakness, impairment of fine motor movements, spasticity, hyperreflexia and abnormal pyramidal signs.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002493","HPO_Synonym__c":"Corticospinal tract dysfunction; Pyramidal tract dysfunction","HPO_Name__c":"Upper motor neuron dysfunction","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A state of fatigue, either physical or mental slowness and sluggishness, with difficulties in initiating or performing simple tasks. Distinguished from apathy which implies indifference and a lack of desire or interest in the task. A person with lethargy may have the desire, but not the energy to engage in personal or socially relevant tasks.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001254","HPO_Synonym__c":"Dullness; Inaction; Inactivity; Languor; Lethargy; Slowness; Torpor","HPO_Name__c":"Lethargy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"A generalized non-motor (absence) seizure is a type of a type of dialeptic seizure that is of electrographically generalized onset. It is a generalized seizure characterized by an interruption of activities, a blank stare, and usually the person will be unresponsive when spoken to. Any ictal motor phenomena are minor in comparison to these non-motor features.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002121","HPO_Synonym__c":"Absence seizure; Absence seizures; Brief seizures with staring spells; Petit mal; Petit mal seizure; Petit mal seizures","HPO_Name__c":"Generalized non-motor (absence) seizure","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"An increase in size of the ventricular system of the brain.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002119","HPO_Synonym__c":"Cerebral ventricular dilatation; Dilated cerebral ventricle; Dilated cerebral ventricles; Dilated ventricles; Enlarged cerebral ventricles; Enlarged ventricles; Enlarged ventricular system; Large cerebral ventricles and cisternae; Ventricular dilatation","HPO_Name__c":"Ventriculomegaly","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An increased concentration of homocystine in the urine.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002156","HPO_Synonym__c":"High urine homocystine levels","HPO_Name__c":"Homocystinuria","HPO_Feature_Type__c":"Lab"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A pattern of thinking and perceiving characterized by a loss of contact with reality, leading to significant changes in thoughts, perceptions, and behaviors.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001345","HPO_Name__c":"Psychotic mentation","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"Hydrocephalus is an active distension of the ventricular system of the brain resulting from inadequate passage of CSF from its point of production within the cerebral ventricles to its point of absorption into the systemic circulation.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000238","HPO_Synonym__c":"Hydrocephaly; Nonsyndromal hydrocephalus; Too much cerebrospinal fluid in the brain","HPO_Name__c":"Hydrocephalus","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"An abnormality of the cerebral white matter.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002500","HPO_Synonym__c":"Abnormality of subcortical white matter; Abnormality of the cerebral white matter; Cerebral white matter abnormalities; Leukoaraiosis; White matter abnormalities; White matter alterations","HPO_Name__c":"Abnormal cerebral white matter morphology","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","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":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0006827","HPO_Synonym__c":"Degeneration of the spinal cord","HPO_Name__c":"Atrophy of the spinal cord","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Peripheral neuropathy is a general term for any disorder of the peripheral nervous system. The main clinical features used to classify peripheral neuropathy are distribution, type (mainly demyelinating versus mainly axonal), duration, and course.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0009830","HPO_Synonym__c":"Peripheral nerve damage; Peripheral neuritis","HPO_Name__c":"Peripheral neuropathy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Loss of strength in the arm, leg, and sometimes face on one side of the body. Hemiplegia refers to a complete loss of strength, whereas hemiparesis refers to an incomplete loss of strength.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001269","HPO_Synonym__c":"Weakness of one side of body","HPO_Name__c":"Hemiparesis","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","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":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A cerebrovascular accident (stroke) that occurs because of thromboembolism.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001727","HPO_Name__c":"Thromboembolic stroke","Feature_System__c":"Blood and Blood-Forming Tissue","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A condition characterized by changes in personality and thought patterns, often accompanied by hallucinations and delusional beliefs, is known as psychosis.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000709","HPO_Synonym__c":"Psychosis","HPO_Name__c":"Psychosis","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A focal-onset seizure is a type of seizure originating within networks limited to one hemisphere. They may be discretely localized or more widely distributed, and may originate in subcortical structures.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0007359","HPO_Synonym__c":"Focal onset seizure; Focal seizure; Focal seizures; Focal-onset seizures; Partial seizure; Partial seizures; Seizure affecting one half of brain","HPO_Name__c":"Focal-onset seizure","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A structural abnormality of the central nervous system.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002011","HPO_Synonym__c":"Abnormality of the central nervous system; Morphological abnormality of the central nervous system; Morphological abnormality of the CNS","HPO_Name__c":"Morphological central nervous system abnormality","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period and affecting the entire musculature.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0008935","HPO_Synonym__c":"Generalized low muscle tone in neonate; Hypotonia, neonatal, generalized","HPO_Name__c":"Generalized neonatal hypotonia","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Impaired feeding performance of an infant as manifested by difficulties such as weak and ineffective sucking, brief bursts of sucking, and falling asleep during sucking. There may be difficulties with chewing or maintaining attention.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0008872","HPO_Name__c":"Feeding difficulties in infancy","Feature_System__c":"Digestive System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"The term gait disturbance can refer to any disruption of the ability to walk.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001288","HPO_Synonym__c":"Abnormal gait; Abnormal walk; Difficulty in walking; Gait abnormalities; Gait difficulties; Gait disturbances; Impaired gait; Walking disability","HPO_Name__c":"Gait disturbance","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"Any abnormality of the eye, including location, spacing, and intraocular abnormalities.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000478","HPO_Synonym__c":"Abnormal eye; Abnormality of the eye","HPO_Name__c":"Abnormality of the eye","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"A structural abnormality of the myelinated axons (white matter) located near the cerebral ventricles.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002518","HPO_Synonym__c":"Abnormality of the periventricular white matter","HPO_Name__c":"Abnormal periventricular white matter morphology","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Cephalgia, or pain sensed in various parts of the head, not confined to the area of distribution of any nerve.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002315","HPO_Synonym__c":"Headache; Headaches","HPO_Name__c":"Headache","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Loss of previously present mental abilities, generally in adults.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001268","HPO_Synonym__c":"Cognitive decline; Cognitive decline, progressive; Intellectual deterioration; Mental deterioration; Progressive cognitive decline","HPO_Name__c":"Mental deterioration","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Failure to thrive (FTT) refers to a child whose physical growth is substantially below the norm.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001508","HPO_Synonym__c":"Faltering weight; FTT; Postnatal failure to thrive; Weight faltering","HPO_Name__c":"Failure to thrive","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","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":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","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":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","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":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"Sudden impairment of blood flow to a part of the brain due to occlusion or rupture of an artery to the brain.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001297","HPO_Synonym__c":"Cerebral vascular events; Cerebrovascular accident; Stroke","HPO_Name__c":"Stroke","Feature_System__c":"Nervous System; Cardiovascular System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Atypical behavior is an abnormality in a person's actions that can be controlled or modulated by the will of the individual. While abnormal behaviors can be difficult to control, they are distinct from other abnormal actions that cannot be affected by the individual's will.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000708","HPO_Synonym__c":"Behavioral abnormality; Behavioral changes; Behavioral disorders; Behavioral disturbances; Behavioral problems; Behavioral symptoms; Behavioral/psychiatric abnormalities; Behavioural symptoms; Behavioural/Psychiatric abnormality; Psychiatric disorders; Psychiatric disturbances","HPO_Name__c":"Atypical behavior","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An increased concentration of cystathionine in the blood.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003286","HPO_Synonym__c":"High blood cystathionine levels","HPO_Name__c":"Cystathioninemia","HPO_Feature_Type__c":"Lab"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A delay in the achievement of motor or mental milestones in the domains of development of a child, including motor skills, speech and language, cognitive skills, and social and emotional skills. This term should only be used to describe children younger than five years of age.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001263","HPO_Synonym__c":"Delayed cognitive development; Delayed development; Delayed developmental milestones; Delayed intellectual development; Delayed milestones; Delayed psychomotor development; Developmental delay; Developmental delay in early childhood; Developmental delay, global; Developmental retardation; GDD; Lack of psychomotor development; Motor and developmental delay; Motormental retardation; Psychomotor delay; Psychomotor development deficiency; Psychomotor development failure; Psychomotor developmental delay; Retarded development; Retarded mental development; Retarded psychomotor development","HPO_Name__c":"Global developmental delay","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An increased concentration of homocystine in the blood.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002160","HPO_Synonym__c":"Elevated blood homocystine; Homocystinemia","HPO_Name__c":"Hyperhomocystinemia","HPO_Feature_Type__c":"Lab"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"A decreased concentration of methionine in the blood.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003658","HPO_Synonym__c":"Decreased plasma methionine; Decreased serum methionine","HPO_Name__c":"Hypomethioninemia","HPO_Feature_Type__c":"Lab"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Frequent (30-79%)","Feature__r":{"HPO_Description__c":"Periods of time during which an individual experiences significant disturbances in their thoughts, perceptions, emotions, and behavior, resulting in a loss of touch with reality. These episodes are hallmark features of psychotic disorders such as schizophrenia, schizoaffective disorder, and certain forms of bipolar disorder.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000725","HPO_Synonym__c":"Psychotic episodes","HPO_Name__c":"Psychotic episodes","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"A bilateral tonic-clonic seizure is a seizure defined by a tonic (bilateral increased tone, lasting seconds to minutes) and then a clonic (bilateral sustained rhythmic jerking) phase.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002069","HPO_Synonym__c":"Bilateral convulsive seizures; Generalised tonic-clonic seizure (without specification of onset); Generalized convulsion; Generalized tonic-clonic seizure (without specification of onset); Grand mal; Grand mal seizures; Seizures, tonic-clonic; Tonic-clonic convulsion; Tonic-clonic convulsions","HPO_Name__c":"Bilateral tonic-clonic seizure","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","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":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Weakness of the muscles of the legs.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0007340","HPO_Synonym__c":"Leg weakness; Lower extremity weakness; Lower limb muscle weakness; Lower limb weakness; Muscle weakness in lower limbs","HPO_Name__c":"Lower limb muscle weakness","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Uncommon (<1-4%)","Feature__r":{"HPO_Description__c":"A generalized myoclonic seizure is a type of generalized motor seizure characterized by bilateral, sudden, brief (<100 ms) involuntary single or multiple contraction of muscles or muscle groups of variable topography (axial, proximal limb, distal). Myoclonus is less regularly repetitive and less sustained than is clonus.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002123","HPO_Synonym__c":"Generalised epileptic myoclonus; Generalised myoclonic seizure; Generalized epileptic myoclonus; Generalized myoclonic seizures; Myoclonus seizures","HPO_Name__c":"Generalized myoclonic seizure","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Formation of a blot clot in a deep vein. The clot often blocks blood flow, causing swelling and pain. The deep veins of the leg are most often affected.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002625","HPO_Synonym__c":"Blood clot in a deep vein; Deep vein thrombosis; Multiple deep venous thrombosis","HPO_Name__c":"Deep venous thrombosis","Feature_System__c":"Blood and Blood-Forming Tissue","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Lack of breathing with no movement of the respiratory muscles and no exchange of air in the lungs. This term refers to a disposition to have recurrent episodes of apnea rather than to a single event.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002104","HPO_Synonym__c":"Absence of spontaneous respiration; Apneic episodes; Apnoea","HPO_Name__c":"Apnea","Feature_System__c":"Respiratory system","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Venous or arterial thrombosis (formation of blood clots) of spontaneous nature and which cannot be fully explained by acquired risk (e.g. atherosclerosis).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001977","HPO_Synonym__c":"Abnormal blood clot; Abnormal blood clotting","HPO_Name__c":"Abnormal thrombosis","Feature_System__c":"Blood and Blood-Forming Tissue","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Concentration or activity of an enzyme is above or below the limits of normal in the blood circulation.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0012379","HPO_Name__c":"Abnormal circulating enzyme concentration or activity","HPO_Feature_Type__c":"Lab"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Occasional (5-29%)","Feature__r":{"HPO_Description__c":"Partial or complete wasting (loss) of brain tissue that was once present.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0012444","HPO_Synonym__c":"Brain degeneration; Brain wasting","HPO_Name__c":"Brain atrophy","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"ORPHA:395","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Spasticity (velocity-dependent increase in tonic stretch reflexes with increased muscle tone and hyperexcitable tendon reflexes) in the muscles of the lower limbs, hips, and pelvis.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002061","HPO_Synonym__c":"Lower extremities spasticity; Lower extremity spasticity; Spastic lower extremities; Spastic lower extremity; Spastic lower limb; Spastic lower limbs; Spasticity in lower extremities; Spasticity in lower extremity; Spasticity in lower limb; Spasticity in lower limbs; Spasticity of lower extremities; Spasticity of lower extremity; Spasticity of lower limb; Spasticity of lower limbs","HPO_Name__c":"Lower limb spasticity","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}}],"tags":{"Cause":["Genetics","Inborn Errors of Metabolism"],"Disease Category":["Genetics","Neurology","Inborn Errors of Metabolism"],"Specialist":["Genetics","Neurology","Epilepsy","Neuromuscular medicine","Pediatrics"],"Account":["Peripheral Neuropathy","Epilepsy"]},"synonyms":["homocysteinuria due to mthfr deficiency"," homocystinuria due to deficiency of n(5,10)-methylenetetrahydrofolate reductase activity"," homocystinuria due to mthfr deficiency"," methylene tetrahydrofolate reductase deficiency"," mthfr deficiency"]}