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Spinocerebellar ataxia type 15/16(SCA15)

MedGen UID:
338301
•Concept ID:
C1847725
•
Disease or Syndrome
Synonyms: SCA15; SCA16 (formerly); Spinocerebellar ataxia 16 (formerly); Spinocerebellar Ataxia Type 15; Spinocerebellar Ataxia Type15
SNOMED CT: Spinocerebellar ataxia type 15/16 (716724006)
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.
Autosomal dominant inheritance (Orphanet)
 
Gene (location): ITPR1 (3p26.1)
 
Monarch Initiative: MONDO:0011694
OMIM®: 606658
Orphanet: ORPHA98769

Definition

Spinocerebellar ataxia type 15 (SCA15) is characterized by slowly progressive gait and limb ataxia, often in combination with ataxic dysarthria, titubation, upper limb postural tremor, mild hyperreflexia, gaze-evoked nystagmus, and impaired vestibuloocular reflex gain. Onset is between ages seven and 72 years, usually with gait ataxia but sometimes with tremor. Affected individuals remain ambulatory for ten to 54 years after symptom onset. Mild dysphagia usually after two or more decades of symptoms has been observed in members of multiple affected families and movement-induced oscillopsia has been described in one member of an affected family. [from GeneReviews]

Additional description

From OMIM
Spinocerebellar ataxia-15 (SCA15) is an autosomal dominant, adult-onset, slowly progressive form of cerebellar ataxia. Most patients also have disabling action and postural tremor, and some have pyramidal tract affection, dorsal column involvement, and gaze palsy. Brain imaging shows cerebellar atrophy mainly affecting the vermis (summary by Synofzik et al., 2011). Autosomal dominant 'pure' cerebellar ataxia, classified as ADCA type III by Harding (1983, 1993), is a genetically heterogeneous disorder (see, e.g., 117210). For a general discussion of autosomal dominant spinocerebellar ataxia, see SCA1 (164400).  http://www.omim.org/entry/606658

Clinical features

From HPO
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.
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Hyperreflexia
MedGen UID:
57738
•Concept ID:
C0151889
•
Finding
Hyperreflexia is the presence of hyperactive stretch reflexes of the muscles.
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Action tremor
MedGen UID:
65875
•Concept ID:
C0234376
•
Sign or Symptom
A tremor present when the limbs are active, either when outstretched in a certain position or throughout a voluntary movement.
See: Feature record | Search on this feature
Postural tremor
MedGen UID:
66696
•Concept ID:
C0234378
•
Sign or Symptom
A type of tremors that is triggered by holding a limb in a fixed position.
See: Feature record | Search on this feature
Scanning speech
MedGen UID:
116113
•Concept ID:
C0240952
•
Mental or Behavioral Dysfunction
An abnormal pattern of speech in which the words are as if measured or scanned; there is a pause after every syllable, and the syllables themselves are pronounced slowly.
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Truncal ataxia
MedGen UID:
96535
•Concept ID:
C0427190
•
Sign or Symptom
Truncal ataxia is a sign of ataxia characterized by instability of the trunk. It usually occurs during sitting.
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Cerebellar atrophy
MedGen UID:
196624
•Concept ID:
C0740279
•
Disease or Syndrome
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.
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Limb ataxia
MedGen UID:
196692
•Concept ID:
C0750937
•
Finding
A kind of ataxia that affects movements of the extremities.
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Gait ataxia
MedGen UID:
155642
•Concept ID:
C0751837
•
Sign or Symptom
A type of ataxia characterized by the impairment of the ability to coordinate the movements required for normal walking. Gait ataxia is characteirzed by a wide-based staggering gait with a tendency to fall.
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Dysmetric saccades
MedGen UID:
322908
•Concept ID:
C1836392
•
Finding
The controller signal for saccadic eye movements has two components
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Impaired smooth pursuit
MedGen UID:
325176
•Concept ID:
C1837458
•
Finding
An impairment of the ability to track objects with the ocular smooth pursuit system, a class of rather slow eye movements that minimizes retinal target motion.
See: Feature record | Search on this feature
Gaze-evoked horizontal nystagmus
MedGen UID:
377895
•Concept ID:
C1853394
•
Finding
Horizontal nystagmus made apparent by looking to the right or to the left.
See: Feature record | Search on this feature
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Term Hierarchy

CClinical test,  RResearch test,  OOMIM,  GGeneReviews,  VClinVar  
  • CROGVSpinocerebellar ataxia type 15/16
Follow this link to review classifications for Spinocerebellar ataxia type 15/16 in Orphanet.

Recent clinical studies

Etiology

Genetic cerebellar ataxias.
Storey E
Semin Neurol 2014 Jul;34(3):280-92. Epub 2014 Sep 5 doi: 10.1055/s-0034-1386766. PMID: 25192506
Clinical features of hereditary spinocerebellar ataxia diagnosed by molecular genetic analysis.
Lau KK, Lam K, Shiu KL, Au KM, Tsoi TH, Chan AY, Li HL, Sheng B
Hong Kong Med J 2004 Aug;10(4):255-9. PMID: 15299171

Diagnosis

Genetic cerebellar ataxias.
Storey E
Semin Neurol 2014 Jul;34(3):280-92. Epub 2014 Sep 5 doi: 10.1055/s-0034-1386766. PMID: 25192506
Clinical features of hereditary spinocerebellar ataxia diagnosed by molecular genetic analysis.
Lau KK, Lam K, Shiu KL, Au KM, Tsoi TH, Chan AY, Li HL, Sheng B
Hong Kong Med J 2004 Aug;10(4):255-9. PMID: 15299171
Relationship of DNA lesions and their repair to chromosomal aberration production.
Bender MA
Basic Life Sci 1980;15:245-65. doi: 10.1007/978-1-4684-3842-0_17. PMID: 7011307

Prognosis

ITPR1-associated spinocerebellar ataxia with craniofacial features-additional evidence for germline mosaicism.
Kleyner R, Ung N, Arif M, Marchi E, Amble K, Gavin M, Madrid R, Lyon G
Cold Spring Harb Mol Case Stud 2023 Dec;9(4) Epub 2024 Jan 10 doi: 10.1101/mcs.a006303. PMID: 37821226Free PMC Article

Clinical prediction guides

ITPR1-associated spinocerebellar ataxia with craniofacial features-additional evidence for germline mosaicism.
Kleyner R, Ung N, Arif M, Marchi E, Amble K, Gavin M, Madrid R, Lyon G
Cold Spring Harb Mol Case Stud 2023 Dec;9(4) Epub 2024 Jan 10 doi: 10.1101/mcs.a006303. PMID: 37821226Free PMC Article

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