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Episodic ataxia type 1(EA1)

MedGen UID:
318554
Concept ID:
C1719788
Disease or Syndrome
Synonyms: ATAXIA, EPISODIC, WITH MYOKYMIA; EA1; MYOKYMIA WITH PERIODIC ATAXIA; PAROXYSMAL ATAXIA WITH NEUROMYOTONIA, HEREDITARY
SNOMED CT: Episodic ataxia type 1 (421182009); Episodic ataxia type 1 (EA1) (421182009)
Modes of inheritance:
Autosomal dominant inheritance
MedGen UID:
141047
Concept ID:
C0443147
Intellectual Product
Source: Orphanet
A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in heterozygotes. In the context of medical genetics, an autosomal dominant disorder is caused when a single copy of the mutant allele is present. Males and females are affected equally, and can both transmit the disorder with a risk of 50% for each child of inheriting the mutant allele.
 
Gene (location): KCNA1 (12p13.32)
 
Monarch Initiative: MONDO:0008047
OMIM®: 160120
Orphanet: ORPHA37612

Definition

Episodic ataxia type 1 (EA1) is a potassium channelopathy characterized by constant myokymia and dramatic episodes of spastic contractions of the skeletal muscles of the head, arms, and legs with loss of both motor coordination and balance. During attacks individuals may experience a number of variable symptoms including vertigo, blurred vision, diplopia, nausea, headache, diaphoresis, clumsiness, stiffening of the body, dysarthric speech, and difficulty in breathing, among others. EA1 may be associated with epilepsy. Other possible associations include delayed motor development, cognitive disability, choreoathetosis, and carpal spasm. Usually, onset is in childhood or early adolescence. [from GeneReviews]

Additional descriptions

From OMIM
Episodic ataxia is a neurologic condition characterized by spells of incoordination and imbalance, often associated with progressive ataxia (Jen et al., 2007). Genetic Heterogeneity of Episodic Ataxia Episodic ataxia is a genetically heterogeneous disorder. See also EA2 (108500), caused by mutation in the CACNA1A gene (601011) on chromosome 19p13; EA3 (606554), which maps to chromosome 1q42; EA4 (606552); EA5, caused by mutation in the CACNB4 gene (601949) on chromosome 2q22-q23; EA6 (612656), caused by mutation in the SLC1A3 gene (600111) on chromosome 5p13; EA7 (611907), which maps to chromosome 19q13; EA8 (616055), which maps to chromosome 1p36-p34; and EA9 (618924), caused by mutation in the SCN2A gene (182390) on chromosome 2q24. Isolated myokymia-2 (see 121200) is associated with mutation in the KCNQ2 gene (602235).  http://www.omim.org/entry/160120
From MedlinePlus Genetics
Episodic ataxia is a group of related conditions that affect the nervous system and cause problems with movement and coordination. People with episodic ataxia have episodes of poor coordination and balance (ataxia). During these episodes, many people also experience dizziness (vertigo), nausea and vomiting, migraines, blurred or double vision, slurred speech, and ringing in the ears (tinnitus). Seizures, muscle weakness, and paralysis that affect one side of the body (hemiplegia) may also occur during these episodes. 

Episodes of ataxia and other symptoms can begin anytime from early childhood to adulthood. They can be triggered by environmental factors such as stress, caffeine, alcohol, certain medications, physical activity, and illness. The duration of episodes may vary from seconds to days, and the frequency ranges from several episodes per day to one or two every few months. Between episodes, affected individuals may have no signs or symptoms. However, some continue to experience ataxia, which may worsen over time.

Additionally, a muscle abnormality called myokymia or an eye abnormality called nystagmus can occur during or between episodes. Myokymia causes muscle cramping; stiffness; or continuous, fine muscle twitching that appears as rippling under the skin. Nystagmus refers to rapid, involuntary eye movements.

Researchers have identified at least 11 types of episodic ataxia, distinguished by their pattern of signs and symptoms, age of onset, length of episodes, and genetic cause.

Some children with episodic ataxia have delayed development of speech or motor skills, such as standing and walking. They may also have learning difficulties.  https://medlineplus.gov/genetics/condition/episodic-ataxia

Clinical features

From HPO
Abnormality of the hand
MedGen UID:
6715
Concept ID:
C0018564
Anatomical Abnormality
An abnormality affecting one or both hands.
Vertigo
MedGen UID:
53006
Concept ID:
C0042571
Sign or Symptom
An abnormal sensation of spinning while the body is actually stationary.
Dysarthria
MedGen UID:
8510
Concept ID:
C0013362
Mental or Behavioral Dysfunction
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.
Headache
MedGen UID:
9149
Concept ID:
C0018681
Sign or Symptom
Cephalgia, or pain sensed in various parts of the head, not confined to the area of distribution of any nerve.
Babinski sign
MedGen UID:
19708
Concept ID:
C0034935
Finding
Upturning of the big toe (and sometimes fanning of the other toes) in response to stimulation of the sole of the foot. If the Babinski sign is present it can indicate damage to the corticospinal tract.
Tremor
MedGen UID:
21635
Concept ID:
C0040822
Sign or Symptom
An unintentional, oscillating to-and-fro muscle movement about a joint axis.
Hyperreflexia
MedGen UID:
57738
Concept ID:
C0151889
Finding
Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.
Spastic gait
MedGen UID:
115907
Concept ID:
C0231687
Finding
Spasticity is manifested by increased stretch reflex which is intensified with movement velocity. This results in excessive and inappropriate muscle activation which can contribute to muscle hypertonia. Spastic gait is characterized by manifestations such as muscle hypertonia, stiff knee, and circumduction of the leg.
Slurred speech
MedGen UID:
65885
Concept ID:
C0234518
Finding
Abnormal coordination of muscles involved in speech.
Incoordination
MedGen UID:
141714
Concept ID:
C0520966
Finding
Myokymia
MedGen UID:
146882
Concept ID:
C0684219
Sign or Symptom
Myokymia consists of involuntary, fine, continuous, undulating contractions that spread across the affected striated muscle.
Hereditary episodic ataxia
MedGen UID:
314033
Concept ID:
C1720189
Disease or Syndrome
Periodic spells of incoordination and imbalance, that is, episodes of ataxia typically lasting from 10 minutes to several hours or days.
Abnormality of the musculature
MedGen UID:
867380
Concept ID:
C4021745
Anatomical Abnormality
Abnormality originating in one or more muscles, i.e., of the set of muscles of body.
Elevated circulating creatine kinase concentration
MedGen UID:
69128
Concept ID:
C0241005
Finding
An elevation of the level of the enzyme creatine kinase (also known as creatine phosphokinase (CK; EC 2.7.3.2) in the blood. CK levels can be elevated in a number of clinical disorders such as myocardial infarction, rhabdomyolysis, and muscular dystrophy.
Blurred vision
MedGen UID:
91020
Concept ID:
C0344232
Finding
Lack of sharpness of vision resulting in the inability to see fine detail.

Professional guidelines

PubMed

Silveira-Moriyama L, Kovac S, Kurian MA, Houlden H, Lees AJ, Walker MC, Roze E, Paciorkowski AR, Mink JW, Warner TT
Dev Med Child Neurol 2018 Jun;60(6):559-565. Epub 2018 Mar 30 doi: 10.1111/dmcn.13744. PMID: 29600549
Almgren M, Schalling M, Lavebratt C
Eur J Paediatr Neurol 2008 Nov;12(6):438-45. Epub 2008 Jan 31 doi: 10.1016/j.ejpn.2007.11.008. PMID: 18242108
Dressler D, Benecke R
J Neurol 2005 Nov;252(11):1299-306. Epub 2005 Oct 10 doi: 10.1007/s00415-005-0006-x. PMID: 16208529

Recent clinical studies

Etiology

Graves TD, Griggs RC, Bundy BN, Jen JC, Baloh RW, Hanna MG; CINCH Investigators
Cerebellum 2023 Aug;22(4):578-586. Epub 2022 Jun 3 doi: 10.1007/s12311-021-01360-6. PMID: 35655106Free PMC Article
Paulhus K, Ammerman L, Glasscock E
Int J Mol Sci 2020 Apr 17;21(8) doi: 10.3390/ijms21082802. PMID: 32316562Free PMC Article
Fernández-Alvarez E, Perez-Dueñas B
Handb Clin Neurol 2013;112:847-52. doi: 10.1016/B978-0-444-52910-7.00004-0. PMID: 23622292
Lerche H, Jurkat-Rott K, Lehmann-Horn F
Am J Med Genet 2001 Summer;106(2):146-59. doi: 10.1002/ajmg.1582. PMID: 11579435
Surtees R
Eur J Pediatr 2000 Dec;159 Suppl 3:S199-203. doi: 10.1007/pl00014403. PMID: 11216900

Diagnosis

Graves TD, Griggs RC, Bundy BN, Jen JC, Baloh RW, Hanna MG; CINCH Investigators
Cerebellum 2023 Aug;22(4):578-586. Epub 2022 Jun 3 doi: 10.1007/s12311-021-01360-6. PMID: 35655106Free PMC Article
Nielsen EN, Ásbjörnsdóttir B, Møller LB, Nielsen JE, Lindquist SG
Cold Spring Harb Mol Case Stud 2022 Oct;8(6) Epub 2022 Oct 28 doi: 10.1101/mcs.a006236. PMID: 36307210Free PMC Article
Kotagal V
Semin Neurol 2012 Nov;32(5):533-7. Epub 2013 May 15 doi: 10.1055/s-0033-1334475. PMID: 23677664
Baloh RW
Handb Clin Neurol 2012;103:595-602. doi: 10.1016/B978-0-444-51892-7.00042-5. PMID: 21827920
Gordon N
Brain Dev 1998 Jan;20(1):9-13. doi: 10.1016/s0387-7604(97)00086-7. PMID: 9533553

Therapy

Dogra D, Meza-Santoscoy PL, Gavrilovici C, Rehak R, de la Hoz CLR, Ibhazehiebo K, Rho JM, Kurrasch DM
Epilepsia 2023 Aug;64(8):2186-2199. Epub 2023 Jun 4 doi: 10.1111/epi.17659. PMID: 37209379
Müller P, Takacs DS, Hedrich UBS, Coorg R, Masters L, Glinton KE, Dai H, Cokley JA, Riviello JJ, Lerche H, Cooper EC
Ann Clin Transl Neurol 2023 Apr;10(4):656-663. Epub 2023 Feb 15 doi: 10.1002/acn3.51742. PMID: 36793218Free PMC Article
Silveira-Moriyama L, Kovac S, Kurian MA, Houlden H, Lees AJ, Walker MC, Roze E, Paciorkowski AR, Mink JW, Warner TT
Dev Med Child Neurol 2018 Jun;60(6):559-565. Epub 2018 Mar 30 doi: 10.1111/dmcn.13744. PMID: 29600549
Kotagal V
Semin Neurol 2012 Nov;32(5):533-7. Epub 2013 May 15 doi: 10.1055/s-0033-1334475. PMID: 23677664
Gordon N
Brain Dev 1998 Jan;20(1):9-13. doi: 10.1016/s0387-7604(97)00086-7. PMID: 9533553

Prognosis

Graves TD, Griggs RC, Bundy BN, Jen JC, Baloh RW, Hanna MG; CINCH Investigators
Cerebellum 2023 Aug;22(4):578-586. Epub 2022 Jun 3 doi: 10.1007/s12311-021-01360-6. PMID: 35655106Free PMC Article
Ovsepian SV, LeBerre M, Steuber V, O'Leary VB, Leibold C, Oliver Dolly J
Pharmacol Ther 2016 Mar;159:93-101. Epub 2016 Jan 26 doi: 10.1016/j.pharmthera.2016.01.005. PMID: 26825872
Zuberi SM, Eunson LH, Spauschus A, De Silva R, Tolmie J, Wood NW, McWilliam RC, Stephenson JB, Kullmann DM, Hanna MG
Brain 1999 May;122 ( Pt 5):817-25. doi: 10.1093/brain/122.5.817. PMID: 10355668

Clinical prediction guides

Graves TD, Griggs RC, Bundy BN, Jen JC, Baloh RW, Hanna MG; CINCH Investigators
Cerebellum 2023 Aug;22(4):578-586. Epub 2022 Jun 3 doi: 10.1007/s12311-021-01360-6. PMID: 35655106Free PMC Article
Dinoi G, Morin M, Conte E, Mor Shaked H, Coppola MA, D'Adamo MC, Elpeleg O, Liantonio A, Hartmann I, De Luca A, Blunck R, Russo A, Imbrici P
Int J Mol Sci 2022 Jul 22;23(15) doi: 10.3390/ijms23158079. PMID: 35897654Free PMC Article
Ovsepian SV, LeBerre M, Steuber V, O'Leary VB, Leibold C, Oliver Dolly J
Pharmacol Ther 2016 Mar;159:93-101. Epub 2016 Jan 26 doi: 10.1016/j.pharmthera.2016.01.005. PMID: 26825872
Graves TD, Cha YH, Hahn AF, Barohn R, Salajegheh MK, Griggs RC, Bundy BN, Jen JC, Baloh RW, Hanna MG; CINCH Investigators
Brain 2014 Apr;137(Pt 4):1009-18. Epub 2014 Feb 26 doi: 10.1093/brain/awu012. PMID: 24578548Free PMC Article
Ebner TJ, Chen G
Neuroscientist 2003 Feb;9(1):37-45. doi: 10.1177/1073858402239589. PMID: 12580338

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