{"Name":"Congenital myasthenic syndrome 2A","DiseaseID__c":"GARD:0009895","id":9895,"encodedName":"congenital-myasthenic-syndrome-2a","IsDeleted":false,"Disease_Name_Full__c":"Congenital myasthenic syndrome 2A","Xref_IDs__c":"C4225374; DOID:0110681; MEDGEN:908185; MONDO:0014581; OMIM:616313","USA_Estimate__c":null,"No_of_Specialist_Tagsa__c":1,"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":3,"Disease_Characteristics_Score__c":5,"No_of_Age_at_Onset__c":0,"Description_Source__c":"MONDO:0014581","Disease_Description__c":"A congenital myasthenic syndrome characterized by autosomal dominant inheritance of postsynaptic neuromuscular junction defects, early-onset progressive muscle weakness, and prolonged opening and activity of the acetylcholine receptor channel that has material basis in heterozygous mutation in the CHRNB1 gene on chromosome 17p13.","GARD_Name__c":"Congenital myasthenic syndrome 2A","GARD_Synonym__c":"cms2a; congenital myasthenic syndrome 2a slow-channel; congenital myasthenic syndrome type 2a; myasthenic syndrome, congenital, 2a, slow-channel","Curated_Disease_Description_Source__c":"MEDGEN:C4225374","Curated_Disease_Description__c":"Congenital myasthenic syndromes (designated as CMS throughout this entry) are characterized by fatigable weakness of skeletal muscle (e.g., ocular, bulbar, limb muscles) with onset at or shortly after birth or in early childhood; rarely, symptoms may not manifest until later in childhood. Cardiac and smooth muscle are usually not involved. Severity and course of disease are highly variable, ranging from minor symptoms to progressive disabling weakness. In some subtypes of CMS, myasthenic symptoms may be mild, but sudden severe exacerbations of weakness or even sudden episodes of respiratory insufficiency may be precipitated by fever, infections, or excitement. Major findings of the neonatal-onset subtype include: respiratory insufficiency with sudden apnea and cyanosis; feeding difficulties; poor suck and cry; choking spells; eyelid ptosis; and facial, bulbar, and generalized weakness. Arthrogryposis multiplex congenita may also be present. Stridor in infancy may be an important clue to CMS. Later childhood-onset subtypes show abnormal muscle fatigability with difficulty in activities such as running or climbing stairs; motor milestones may be delayed; fluctuating eyelid ptosis and fixed or fluctuating extraocular muscle weakness are common presentations.","Curated_USA_Estimate_Source__c":null,"Curated_USA_Estimate__c":null,"Age_at_Onset_Snippet_Text__c":null,"SourceID__c":"OMIM:616313","Deprecated__c":"No","Disease_Concept_Type__c":"Rare Disease Entity","MONDO_ID__c":"MONDO:0014581","ORPHANET_ID__c":null,"Replaced_By_ID__c":null,"Display_Spanish_Disease_Name__c":null,"Spanish_Description_Source__c":null,"Spanish_Description__c":null,"Spanish_Disease_Name__c":null,"Spanish_GARD_Synonym__c":null,"Category_Linearization__c":null,"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":"Congenital myasthenic syndromes (designated as CMS throughout this entry) are characterized by fatigable weakness of skeletal muscle (e.g., ocular, bulbar, limb muscles) with onset at or shortly after birth or in early childhood; rarely, symptoms may not manifest until later in childhood. Cardiac and smooth muscle are usually not involved. Severity and course of disease are highly variable, ranging from minor symptoms to progressive disabling weakness. In some subtypes of CMS, myasthenic symptoms may be mild, but sudden severe exacerbations of weakness or even sudden episodes of respiratory insufficiency may be precipitated by fever, infections, or excitement. Major findings of the neonatal-onset subtype include: respiratory insufficiency with sudden apnea and cyanosis; feeding difficulties; poor suck and cry; choking spells; eyelid ptosis; and facial, bulbar, and generalized weakness. Arthrogryposis multiplex congenita may also be present. Stridor in infancy may be an important clue to CMS. Later childhood-onset subtypes show abnormal muscle fatigability with difficulty in activities such as running or climbing stairs; motor milestones may be delayed; fluctuating eyelid ptosis and fixed or fluctuating extraocular muscle weakness are common presentations.","Curated_Disease_Description_Source__c":"MEDGEN:C4225374","GARD_Synonym__c":"cms2a; congenital myasthenic syndrome 2a slow-channel; congenital myasthenic syndrome type 2a; myasthenic syndrome, congenital, 2a, slow-channel","Name":"Congenital myasthenic syndrome 2A","estimateUsa":""}],"Organization_Supported_Diseases__c":[{"Account_Name__c":"Muscular Dystrophy Association","Website__c":"https://www.mda.org"}],"GARD_Disease_Tag__c":[{"Tag_Name__c":"Neuromuscular medicine","Tag_Category__c":"Specialist","curated_tag_name":"Neuromuscular medicine"}],"Diagnosis__c":[{"Type__c":"GTR","Curie__c":"MEDGEN:C4225374"}],"External_Identifier_Disease__c":[{"URL__c":"https://raresource.nih.gov/diseases/filter/0009895","Source__c":"RareSource"},{"URL__c":"https://www.ncbi.nlm.nih.gov/books/NBK1168","Source__c":"Gene Review","Xref__c":"NBK1168"},{"URL__c":"https://uts.nlm.nih.gov/uts/umls/concept/C4225374","Source__c":"C4225374","Xref__c":"C4225374"},{"URL__c":"https://www.ebi.ac.uk/ols4/ontologies/doid/classes?obo_id=DOID%3A0110681","Source__c":"MONDO:0014581","Xref__c":"DOID:0110681"},{"URL__c":"https://www.omim.org/entry/616313","Source__c":"C4225374; MONDO:0014581","Xref__c":"OMIM:616313"},{"URL__c":"https://www.ncbi.nlm.nih.gov/medgen/?term=908185","Source__c":"C4225374","Xref__c":"MEDGEN:908185"},{"URL__c":"http://purl.obolibrary.org/obo/MONDO_0014581","Source__c":"GARD:0009895","Xref__c":"MONDO:0014581"}],"GARD_Disease_Gene__c":[{"GeneSymbol__c":"CHRNB1","Gene_Type__c":"protein-coding gene","Causal_Gene__c":true}],"Inheritance__c":["Autosomal dominant"],"GARD_Disease_Feature__c":[{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A type of weakness that occurs after a muscle group is used and lessens if the muscle group has some rest. That is, there is diminution of strength with repetitive muscle actions.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003473","HPO_Synonym__c":"Fatigable weakness of limb muscles; Generalized muscle weakness due to defect at the neuromuscular junction; Myasthenia; Myasthenic weakness; Proximal muscle weakness due to defect at the neuromuscular junction","HPO_Name__c":"Fatigable weakness","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A failure to achieve the ability to sit at an appropriate developmental stage. Most children sit with support at 6 months of age and sit steadily without support at 9 months of age.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0025336","HPO_Name__c":"Delayed ability to sit","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","Feature__r":{"HPO_Description__c":"A disorder of muscle unrelated to impairment of innervation or neuromuscular junction.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003198","HPO_Synonym__c":"Muscle tissue disease; Myopathic changes","HPO_Name__c":"Myopathy","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Facial height (length) is more than 2 standard deviations above the mean (objective); or, an apparent increase in the height (length) of the face (subjective).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000276","HPO_Synonym__c":"Elongation of face; Increased height of face; Increased length of face; Increased vertical dimension of face; Long face; Long facies; Vertical elongation of face; Vertical enlargement of face; Vertical excess of face; Vertical Facial Excess; Vertical hyperplasia of face; Vertical overgrowth of face","HPO_Name__c":"Long face","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A failure to achieve the ability to walk at an appropriate developmental stage. Most children learn to walk in a series of stages, and learn to walk short distances independently between 12 and 15 months.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0031936","HPO_Synonym__c":"Delayed walking","HPO_Name__c":"Delayed ability to walk","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Increased susceptibility to fatigue.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003388","HPO_Name__c":"Easy fatigability","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An abnormally high degree of muscle fiber size variation. This phenotypic feature can be observed upon muscle biopsy.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003557","HPO_Synonym__c":"Increased fiber size variation; Increased variability in muscle fiber size; Increased variation in fiber size; Increased variation in muscle fiber size; Variation in muscle fiber size","HPO_Name__c":"Increased variability in muscle fiber diameter","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A persistent (minutes to hours) abnormal increase in the pitch (frequency) of the voice for the context or social situation or significantly different from baseline of the individual.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001620","HPO_Synonym__c":"High pitched voice; High-pitched voice","HPO_Name__c":"Abnormally high-pitched voice","Feature_System__c":"Nervous System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An inadequate sucking reflex, resulting in the difficult of newborns to be breast-fed.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002033","HPO_Synonym__c":"Poor suck; Poor sucking; Sucking weakness","HPO_Name__c":"Poor suck","Feature_System__c":"Digestive System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Difficulty to maintain correct position of the head while standing or sitting. Infant head lag is observed when the head seems to flop around or lags posteriorly behind the trunk. Several articles have maintained that head lag should be absent by age 3 to 4 months.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0002421","HPO_Synonym__c":"Delay in head control; Delay in head righting; Infant head lag; Poor head control","HPO_Name__c":"Poor head control","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","Feature__r":{"HPO_Description__c":"Bizygomatic (upper face) and bigonial (lower face) width are both more than 2 standard deviations below the mean (objective); or, an apparent reduction in the width of the upper and lower face (subjective).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000275","HPO_Synonym__c":"Decreased breadth of face; Decreased horizontal dimension of face; Decreased transverse dimension of face; Decreased width of face; Horizontal deficiency of face; Horizontal hypoplasia of face; Horizontal insufficiency of face; Narrow face; Narrow facies; Thin facies; Transverse deficiency of face; Transverse hypoplasia of face; Transverse insufficiency of face","HPO_Name__c":"Narrow face","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","Feature__r":{"HPO_Description__c":"Facial nerve palsy is a dysfunction of cranial nerve VII (the facial nerve) that results in inability to control facial muscles on the affected side with weakness of the muscles of facial expression and eye closure. This can either be present in unilateral or bilateral form.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0010628","HPO_Synonym__c":"Bell's palsy; Cranial nerve VII palsy; Facial nerve palsy; Facial nerve paralysis; Facial palsy, unilateral or bilateral; Seventh cranial nerve palsy; VII th cranial nerve palsy","HPO_Name__c":"Facial palsy","Feature_System__c":"Nervous System; Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","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:616313","Feature__r":{"HPO_Description__c":"Muscular hypotonia (abnormally low muscle tone) manifesting in the neonatal period.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001319","HPO_Synonym__c":"Hypotonia, in neonatal onset; Hypotonia, neonatal; Low muscle tone, in neonatal onset","HPO_Name__c":"Neonatal hypotonia","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Reduced strength and weakness of the muscles of the arms and legs.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003690","HPO_Synonym__c":"Limb muscle weakness; Limb weakness","HPO_Name__c":"Limb muscle weakness","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Paralysis of one or more extraocular muscles that are responsible for eye movements.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000602","HPO_Synonym__c":"Eye muscle paralysis; Paralysis of extraocular eye movement","HPO_Name__c":"Ophthalmoplegia","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"The presence of skeletal muscular atrophy (which is also known as amyotrophy).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003202","HPO_Synonym__c":"Amyotrophy; Amyotrophy involving the extremities; Muscle atrophy; Muscle atrophy, neurogenic; Muscle degeneration; Muscle hypotrophy; Muscle wasting; Muscular atrophy; Neurogenic muscle atrophy; Neurogenic muscle atrophy, especially in the lower limbs; Neurogenic muscular atrophy","HPO_Name__c":"Skeletal muscle atrophy","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A compound muscle action potential (CMAP) is a type of electromyography (EMG). CMAP refers to a group of almost simultaneous action potentials from several muscle fibers in the same area evoked by stimulation of the supplying motor nerve and are recorded as one multipeaked summated action potential. This abnormality refers to a greater than normal decrease in the amplitude during the course of the investigation.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003403","HPO_Synonym__c":"EMG: decremental response of CMAP to repetitive nerve stimulation","HPO_Name__c":"EMG: decremental response of compound muscle action potential to repetitive nerve stimulation","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Procedure_EMG"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"An abnormal predominance of type I muscle fibers (in general, this feature can only be observed on muscle biopsy).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003803","HPO_Synonym__c":"Type I muscle fiber predominance","HPO_Name__c":"Type 1 muscle fiber predominance","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000508","HPO_Synonym__c":"Blepharoptosis; Drooping upper eyelid; Eyelid ptosis; Palpebral ptosis","HPO_Name__c":"Ptosis","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A type of knee joint contracture in which the knee is in a fixed bent (flexed) configuration such that it cannot be straightened actively or passively.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0006380","HPO_Synonym__c":"Flexion contracture of knees; Flexion contractures at both knees; Flexion contractures of knees; Flexion deformity of the knee; Knee flexion contractures; Knee flexion deformity","HPO_Name__c":"Knee flexion contracture","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Height of the palate more than 2 SD above the mean (objective) or palatal height at the level of the first permanent molar more than twice the height of the teeth (subjective).","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0000218","HPO_Synonym__c":"Elevated palate; High arched palate; High palate; High, arched palate; High-arched palate; Increased palatal height; Palate high-arched; Palate, high-arched","HPO_Name__c":"High palate","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"Fiber splitting or branching is a common finding in human and rat skeletal muscle pathology. Fiber splitting refers to longitudinal halving of the complete fiber, while branching originates from a regenerating end of a necrotic fiber as invaginations of the sarcolemma. In fiber branching, one end of the fiber remains intact as a single entity, while the other end has several branches.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0003555","HPO_Synonym__c":"Fiber splitting; Fibre splitting; Muscle fiber splitting","HPO_Name__c":"Muscle fiber splitting","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}},{"Provided_By__c":"OMIM:616313","HPO_Frequency__c":"Very frequent (80-99%)","Feature__r":{"HPO_Description__c":"A flexion contracture is a bent (flexed) joint that cannot be straightened actively or passively. It is thus a chronic loss of joint motion due to structural changes in muscle, tendons, ligaments, or skin that prevents normal movement of joints.","HPO_Feature_URL__c":"https://hpo.jax.org/browse/term/HP:0001371","HPO_Synonym__c":"Flexed joint that cannot be straightened; Flexion contractures; Flexion contractures of joints","HPO_Name__c":"Flexion contracture","Feature_System__c":"Musculoskeletal System","HPO_Feature_Type__c":"Symptom"}}],"tags":{"Specialist":["Neuromuscular medicine"]},"synonyms":["cms2a"," congenital myasthenic syndrome 2a slow-channel"," congenital myasthenic syndrome type 2a"," myasthenic syndrome, congenital, 2a, slow-channel"]}