SCA1ATXN1
Often broader than balance
May include swallowing difficulty, spasticity, neuropathy, weakness, and abnormal eye movements.
NEW NORMAL
Ataxia describes coordination problems.
It is a neurological sign—not one diagnosis. Understanding the pattern and cause helps shape what comes next.
THE BASICS
Different causes can produce similar symptoms.
Ataxia may affect walking, balance, hand movements, speech, swallowing, or eye movements. It can be inherited or acquired, sudden or gradual, and stable or progressive.
Because causes differ, a careful medical evaluation matters. Testing may include a neurological examination, imaging, blood work, genetic testing, or other studies based on the history.
My diagnosis is idiopathic cerebellar degeneration attributed to an autoimmune condition involving CASPR2. It is an ultra-rare disease with ~1000 cases worldwide.
NEWLY DIAGNOSED
Cerebellar ataxia at a glance
A visual overview of the cerebellum, common symptoms, broad causes, rehabilitation roles, and useful next steps.
SPINOCEREBELLAR ATAXIAS
One family of conditions—not one disease.
Numbered SCA labels describe genetic ataxias, but some numbers share a gene, remain unresolved, or have been reassigned. They overlap in balance, coordination, speech, and eye-movement problems, but differ in typical age of onset, other affected systems, and average rate of progression.
The number is a label, not a severity ranking. Two people with the same SCA can still have different symptoms and timelines. This list covers numbered labels through SCA52; it is a reference to classification, not a way to diagnose by symptoms. The reference to the relevant gene is included. Deep analysis of this information starts with Springer, a global leader in scientific publishing. Reference https://link.springer.com/article/10.1007/s12311-024-01703-z
SCA2ATXN2
Slow eye movements can stand out
Often overlaps with SCA1 and SCA3; neuropathy, reduced reflexes, tremor, or parkinsonism may occur.
SCA3ATXN3
The widest symptom range
Also called Machado–Joseph disease. Spasticity, dystonia, neuropathy, eye-movement changes, or parkinsonism may accompany ataxia.
SCA4ZFHX3
Genetic basis
GGC repeat expansion in ZFHX3; sensory neuropathy can accompany ataxia.
SCA5SPTBN2
Genetic basis
Variants in SPTBN2; often a predominantly cerebellar presentation.
SCA6CACNA1A
Often more cerebellar-focused
Commonly begins later and progresses more slowly on average. Vertigo or episodic symptoms may occur in some families.
SCA7ATXN7
Vision loss is distinctive
Retinal degeneration can cause color and central-vision problems, sometimes before obvious coordination changes.
SCA8ATXN8 / ATXN8OS
Genetic basis
Repeat expansion; a positive result needs careful clinical interpretation.
SCA9Unassigned
Classification note
Historical number without an established gene or confirmed subtype.
SCA10ATXN10
Genetic basis
ATTCT repeat expansion; seizures occur in some families.
SCA11TTBK2
Genetic basis
Variants in TTBK2; often a slowly progressive cerebellar syndrome.
SCA12PPP2R2B
Genetic basis
Repeat expansion; action tremor may appear before ataxia.
SCA13KCNC3
Genetic basis
Variants in a potassium-channel gene; onset varies widely.
SCA14PRKCG
Genetic basis
Variants in PRKCG; often a slowly progressive cerebellar syndrome.
SCA15ITPR1
Genetic basis
Shares a genetic basis with SCA16; ITPR1 variants or deletions.
SCA16ITPR1
Genetic basis
Overlaps with SCA15; the two labels are often grouped as SCA15/16.
SCA17TBP
Cognition may be prominent
Movement changes can occur with cognitive, psychiatric, dystonic, parkinsonian, or seizure symptoms.
SCA18Locus 7q22–q32
Genetic basis
Cause unresolved; IFRD1 has been proposed as a candidate gene.
SCA19KCND3
Genetic basis
Shares a genetic basis with SCA22; often grouped as SCA19/22.
SCA2011q12 duplication
Genetic basis
A multigene duplication reported in a family; no single causative gene established.
SCA21TMEM240
Genetic basis
Variants in TMEM240; cognitive changes can accompany ataxia.
SCA22KCND3
Genetic basis
Overlaps genetically with SCA19; often grouped as SCA19/22.
SCA23PDYN
Genetic basis
Variants in PDYN; a rare dominant cerebellar ataxia.
SCA24Reassigned
Classification note
Former SCA24 designation was reclassified as recessive SCAR4.
SCA25PNPT1
Genetic basis
A rare PNPT1-associated form; evidence comes from limited families.
SCA26EEF2
Genetic basis
Variants in EEF2; a rare cerebellar-predominant form.
SCA27FGF14
Genetic basis
SCA27A: FGF14 sequence variants; tremor or movement changes may occur.
SCA27BFGF14
Repeat expansion
SCA27B: GAA repeat expansion; often adult onset with episodic features or vertigo.
SCA28AFG3L2
Genetic basis
Variants in AFG3L2; eye movement changes or spasticity may occur.
SCA29ITPR1
Genetic basis
ITPR1-related form that often begins early and can be nonprogressive.
SCA30Locus 4q34–q35
Genetic basis
Genetic locus mapped; a causative gene is not established.
SCA31BEAN1
Genetic basis
TGGAA repeat expansion; especially described in Japan.
SCA32Locus 7q32–q33
Genetic basis
Genetic locus mapped; a causative gene is not established.
SCA33Unassigned
Classification note
Number has not been assigned to a confirmed SCA subtype.
SCA34ELOVL4
Genetic basis
Variants in ELOVL4; skin changes can accompany ataxia.
SCA35TGM6
Genetic basis
Variants in TGM6; a rare reported dominant form.
SCA36NOP56
Genetic basis
GGCCTG repeat expansion; tongue atrophy or fasciculations may occur.
SCA37DAB1
Genetic basis
ATTTC repeat insertion; a rare adult-onset form.
SCA38ELOVL5
Genetic basis
Variants in ELOVL5; a rare dominant cerebellar ataxia.
SCA3911q21–q22 duplication
Classification note
Proposed designation based on a large duplication in one family; not formally assigned in the cited review.
SCA40CCDC88C
Genetic basis
Variants in CCDC88C; spasticity or parkinsonian signs may occur.
SCA41TRPC3
Genetic basis
Variants in a calcium-signaling channel gene.
SCA42CACNA1G
Genetic basis
Variants in a calcium-channel gene; eye movement signs may occur.
SCA43MME
Genetic basis
Variants in MME; peripheral neuropathy may accompany ataxia.
SCA44GRM1
Genetic basis
Variants in GRM1; a rare dominant form distinct from recessive GRM1 ataxia.
SCA45FAT2
Genetic basis
Variants in FAT2; a rare dominant cerebellar ataxia.
SCA46PLD3
Genetic basis
Variants in PLD3; a rare reported form.
SCA47PUM1
Genetic basis
Variants in PUM1; can include developmental or cognitive features.
SCA48STUB1
Genetic basis
Variants in STUB1; cognition or behavior may also be affected.
SCA49SAMD9L
Genetic basis
Variants in SAMD9L; blood-cell abnormalities may accompany ataxia.
SCA50NPTX1
Genetic basis
Variants in NPTX1; eye movement and cognitive changes may occur.
SCA51THAP11
Genetic basis
CAG repeat expansion; included in NIH genetic disease records.
SCA52RAB3A
Genetic basis
Variants in RAB3A; a recently characterized, usually adult-onset form.
Why testing matters: Symptoms overlap too much to identify an SCA reliably by examination alone. Genetic testing—often including repeat-expansion testing—is usually needed to confirm the type.