Spinocerebellar ataxia type 12 (SCA12) is a very rare subtype of type I autosomal dominant cerebellar ataxia (ADCA type I). It is characterized by the presence of action tremor associated with relatively mild cerebellar ataxia. Associated pyramidal and extrapyramidal signs and dementia have been reported¹.

Prevalence

Frequent in India; rare in other populations².

Age of Onset

Typical: 26-50; Range: 8-62^3,4.

HPO Terms

–

Association

Mendelian

Locus

hg19 chr5:146258290-146258322

hg38 chr5:146878727-146878759

t2t chr5:147414733-147414780

Details

Benign range is 6-32 repeats, intermediate range 40-49, and pathogenic range is 51-78⁵; intermediate alleles are associated with reduced penetrance⁶.

Mechanism

GoF

Polyalanine gain of function associated with RAN translation⁷.

Detection

RP-PCR generally detects expansions, while PCR fragment analysis approximates allele size. Large expansions may require Southern blot confirmation [@pmid:35262663; @pmid:10581021].

Year

1999⁸

Location in Gene

5' UTR

Gene Strand

Alleles

Ref. Motif

GCT

Ranges

Benign (ref.)

–

Benign (gene)

–

Pathogenic (ref.)

GCT

Pathogenic (gene)

AGC

Unknown (ref.)

–

Unknown (gene)

–

Interruption (ref.)

–

Interruption (gene)

–

gnomAD

References

Direct supporting references for info on this page.

Ontology Lookup Service (OLS)

mondo:0011439

Spinocerebellar ataxias in Asia: Prevalence, phenotypes and management.

Teije,van Prooije, Norlinah Mohamed,Ibrahim, Shahrul,Azmin, Bart,van de Warrenburg

Parkinsonism & related disorders · 2021-10-22

pmid:34711523

3omim:604326

Abnormal Amyloidogenesis Identified in Plasma of Patients with Spinocerebellar Ataxia Type 12.

Rebecca,Banerjee, Swarnava,Sengupta, Jyoti,Rungta, Sabbir,Ansari, Sattwika,Banerjee, Bishmita,Biswas, Rakhi,Pal, Sumantra,Chattarji, Supriyo,Choudhury, Hrishikesh,Kumar

Cerebellum (London, England) · 2026-05-09

pmid:42105155

The Frequency of Intermediate Alleles in Patients with Cerebellar Phenotypes.

Elena,Capacci, Silvia,Bagnoli, Giulia,Giacomucci, Costanza Maria,Rapillo, Alessandra,Govoni, Valentina,Bessi, Cristina,Polito, Irene,Giotti, Alice,Brogi, Elisabetta,Pelo, Sandro,Sorbi, Benedetta,Nacmias, Camilla,Ferrari

Cerebellum (London, England) · 2023-10-31

pmid:37906407

SCA12 is a rare locus for autosomal dominant cerebellar ataxia: a study of an Indian family.

H,Fujigasaki, I C,Verma, A,Camuzat, R L,Margolis, C,Zander, A S,Lebre, L,Jamot, R,Saxena, I,Anand, S E,Holmes, C A,Ross, A,Dürr, A,Brice

Annals of neurology · 2001-01-01

pmid:11198281

Sequence composition changes in short tandem repeats: heterogeneity, detection, mechanisms and clinical implications.

Indhu-Shree,Rajan-Babu, Egor,Dolzhenko, Michael A,Eberle, Jan M,Friedman

Nature reviews. Genetics · 2024-03-11

pmid:38467784

Expansion of a novel CAG trinucleotide repeat in the 5' region of PPP2R2B is associated with SCA12.

S E,Holmes, E E,O'Hearn, M G,McInnis, D A,Gorelick-Feldman, J J,Kleiderlein, C,Callahan, N G,Kwak, R G,Ingersoll-Ashworth, M,Sherr, A J,Sumner, A H,Sharp, U,Ananth, W K,Seltzer, M A,Boss, A M,Vieria-Saecker, J T,Epplen, O,Riess, C A,Ross, R L,Margolis

Nature genetics · 1999-12-01

pmid:10581021

Additional Literature

Additional literature related to this locus.

Raw PubMed search results
(All PubMed results returned by searching for this gene, tandem repeats, and disease, in medline format)

Abnormal Amyloidogenesis Identified in Plasma of Patients with Spinocerebellar Ataxia Type 12.

Rebecca,Banerjee, Swarnava,Sengupta, Jyoti,Rungta, Sabbir,Ansari, Sattwika,Banerjee, Bishmita,Biswas, Rakhi,Pal, Sumantra,Chattarji, Supriyo,Choudhury, Hrishikesh,Kumar

Cerebellum (London, England) · 2026-05-09

pmid:42105155

Detection of short tandem repeat expansions on a targeted neurological gene panel using STRipy improves the diagnostic rate for ataxias.

Carolin K,Scriba, Chiara,Folland, Michael,Black, Jessica,Baker, Daniel,Abromeit, Samantha,Saw, Mei-Ting,Chiew, Rebecca,Gooding, Nigel G,Laing, Mark R,Davis, Gianina,Ravenscroft

Brain communications · 2026-03-16

pmid:42038259

Precision Diagnosis of Wilson Disease Using a MultiGene Panel: Insights From a Prospective Cohort Study.

Jie,Lin, You-Liang,Wang, Yongqiang,Qu, Senwei,Dong, Yaofeng,Fang, Rukai,Chen, Ying,Ding, Weihong,Lin, Jian,Chen, Naiqing,Cai, Ning,Wang, Wan-Jin,Chen, Yi,Lin, Zhiqiang,Wang

Neurology. Genetics · 2026-03-03

pmid:41788301

Short tandem repeat expansions in patients with neurodegenerative dementia.

Yuan,Zhu, Xuewen,Xiao, Yiliang,Liu, Zheng,Wang, Tengfei,Luo, Tianyan,Xu, Qijie,Yang, Xiaoli,Hao, Cong,Zhang, Sizhe,Zhang, Shilin,Luo, Yafang,Zhou, Xinxin,Liao, Yun,Tian, Ling,Weng, Liangjuan,Fang, Beisha,Tang, Bin,Jiao, Jinchen,Li, Lu,Shen

EBioMedicine · 2026-02-26

pmid:41762523

Mitochondrial quality control gene expression in peripheral blood mononuclear cells of SCA12 patients.

Sabbir,Ansari, Jyoti,Rungta, Rebecca,Banerjee, Swarnava,Sengupta, Bishmita,Biswas, Rakhi,Pal, Sanjit,Dey, Sumantra,Chattarji, Jacky,Ganguly, Supriyo,Choudhury, Hrishikesh,Kumar

Parkinsonism & related disorders · 2026-02-12

pmid:41691974

Non-Huntington's disease chorea: an expanding universe with acquired causes.

Francisco,Cardoso, Débora,Maia, Ricardo,Maciel, Jonathan,Carr, Taku,Hatano, Alexandra,Durr, Werner,Poewe

Brain : a journal of neurology · 2026-01-30

pmid:41612618

Association of Non-Coding Repeat Expansions with Parkinson's Disease Risk: Evidence from a UK Biobank-Based Whole-Genome Sequencing Study.

Zhen,Hu, Qin-Qin,Yan, Jing-Jin,Wan, Yu,Fan, Jun,Liu

Movement disorders : official journal of the Movement Disorder Society · 2025-10-11

pmid:41074692

Diagnostic yield and limitations of whole-genome sequencing for hereditary cerebellar ataxia.

Wai Yan,Yau, Roisin,Sullivan, Emer,O'Connor, David,Pellerin, Michael H,Parkinson, Paola,Giunti, Marie-Josée,Dicaire, Matt C,Danzi, Stephan,Züchner, Bernard,Brais, Nicholas W,Wood, Henry,Houlden, Jana,Vandrovcova

Brain communications · 2025-05-17

pmid:40488180

De novo missense variants in the PP2A regulatory subunit PPP2R2B in a neurodevelopmental syndrome: potential links to mitochondrial dynamics and spinocerebellar ataxias.

Priyanka,Sandal, Chian Ju,Jong, Ronald A,Merrill, Grace J,Kollman, Austin H,Paden, Eric G,Bend, Jennifer,Sullivan, Rebecca C,Spillmann, Vandana,Shashi, Anneke T,Vulto-van Silfhout, Rolph,Pfundt, Bert B A,de Vries, Pan P,Li, Louise S,Bicknell, Stefan,Strack

Human molecular genetics · 2025-01-29

pmid:39565297

Locus SCA12 PPP2R2B

Disease

Locus

Alleles

gnomAD

References

Additional Literature