Spinocerebellar ataxia-7 (SCA7) is an autosomal dominant neurodegenerative disorder characterized by adult onset of progressive cerebellar ataxia associated with pigmental macular dystrophy¹.

Prevalence

0.999 300,000

<1/300,000: predominantly found in those with North European and African ancestry².

Age of Onset

Typical: 4-48³; Range: 0-92^2,4.

HPO Terms

HP:0000514 Slow saccadic eye movements HP:0000529 Progressive visual loss HP:0000548 Cone/cone-rod dystrophy HP:0000572 Visual loss HP:0000580 Pigmentary retinopathy HP:0000597 Ophthalmoparesis HP:0000602 Ophthalmoplegia HP:0000608 Macular degeneration HP:0000613 Photophobia HP:0000618 Blindness HP:0000623 Supranuclear ophthalmoplegia HP:0000639 Nystagmus HP:0000648 Optic atrophy HP:0000709 Psychosis HP:0001098 Abnormal fundus morphology HP:0001251 Ataxia HP:0001257 Spasticity HP:0001260 Dysarthria HP:0001263 Global developmental delay HP:0001268 Mental deterioration HP:0001270 Motor delay HP:0001272 Cerebellar atrophy HP:0001310 Dysmetria HP:0001319 Neonatal hypotonia HP:0001324 Muscle weakness HP:0001337 Tremor HP:0001347 Hyperreflexia HP:0001508 Failure to thrive HP:0001635 Congestive heart failure HP:0002015 Dysphagia HP:0002059 Cerebral atrophy HP:0002071 Abnormality of extrapyramidal motor function HP:0002072 Chorea HP:0002073 Progressive cerebellar ataxia HP:0002075 Dysdiadochokinesis HP:0002310 Orofacial dyskinesia HP:0002542 Olivopontocerebellar atrophy HP:0003474 Somatic sensory dysfunction HP:0003487 Babinski sign HP:0007663 Reduced visual acuity HP:0011968 Feeding difficulties HP:0012047 Hemeralopia HP:0012452 Restless legs

Association

Mendelian

Locus

hg19 chr3:63898360-63898391

hg38 chr3:63912684-63912715

t2t chr3:63956302-63956333

Details

Benign alleles range from 4-27⁵, with intermediate alleles ranging from premutations (28-33) to reduced penetrance (34-36)². Interruptions observed include CAA⁶. CAG repeat expansions have been detected in a circular RNA (circATXN7(3,4).1) derived from this locus, in SCA7 patient fibroblasts, cerebellum, and blood, though it is unclear if this contributes to disease⁷.

Mechanism

GoF

Polyglutamine expansion leading to gain of function; toxic misfolded intermediate suspected^2,8.

Detection

Short-read WGS cannot accurately detect repeat expansions at this locus. PCR fragment analysis or RP-PCR has detected expansions and sized most normal or moderate pathogenic alleles, while very large expansions have been detected with Southern blotting or long-read sequencing².

Year

1996⁹

Location in Gene

Coding Exon 1, 2, or 3 (depending on isoform)

Gene Strand

Alleles

Ref. Motif

CAG

Ranges

Benign (ref.)

–

Benign (gene)

–

Pathogenic (ref.)

CAG

Pathogen. (gene)

CAG

Unknown (ref.)

–

Unknown (gene)

–

Interruption (ref.)

–

Interrup. (gene)

–

gnomAD

References

Direct supporting references for info on this page.

1omim:164500

Spinocerebellar Ataxia Type 7

Albert R.,La Spada

GeneReviews® · 1993-01-01

genereviews:NBK1256

Clinical and genetic study of a Chinese family with spinocerebellar ataxia type 7.

Yan,Han, Benqiang,Deng, Mingyuan,Liu, Jianming,Jiang, Shuai,Wu, Yangtai,Guan

Neurology India · 2010-01-01

pmid:20739808

Spinocerebellar ataxia type 7 associated with pigmentary retinal dystrophy.

A,Michalik, J-J,Martin, C,Van Broeckhoven

European journal of human genetics : EJHG · 2004-01-01

pmid:14571264

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

Comprehensive genetic diagnosis of tandem repeat expansion disorders with programmable targeted nanopore sequencing.

Igor,Stevanovski, Sanjog R,Chintalaphani, Hasindu,Gamaarachchi, James M,Ferguson, Sandy S,Pineda, Carolin K,Scriba, Michel,Tchan, Victor,Fung, Karl,Ng, Andrea,Cortese, Henry,Houlden, Carol,Dobson-Stone, Lauren,Fitzpatrick, Glenda,Halliday, Gianina,Ravenscroft, Mark R,Davis, Nigel G,Laing, Avi,Fellner, Marina,Kennerson, Kishore R,Kumar, Ira W,Deveson

Science advances · 2022-03-04

pmid:35245110

Discovery of a mutation-containing circRNA in polyglutamine disease through systematic analysis of RNAs with CAG repeats.

Weronika,Pawlik, Magdalena,Woźna-Wysocka, Magdalena,Jazurek-Ciesiołka, Jarosław,Dulski, Tomasz M,Witkoś, Agata,Ciołak, Emilia,Kozłowska, Edyta,Kościańska, Luke C,Bartelt, Julien,Philippe, Jarosław,Sławek, Paweł M,Świtoński, Albert R,La Spada, Agnieszka,Fiszer

RNA biology · 2026-06-24

pmid:42340810

Molecular pathogenesis and cellular pathology of spinocerebellar ataxia type 7 neurodegeneration.

Gwenn A,Garden, Albert R,La Spada

Cerebellum (London, England) · 2008-01-01

pmid:18418675

An expanded CAG repeat sequence in spinocerebellar ataxia type 7.

K,Lindblad, M L,Savontaus, G,Stevanin, M,Holmberg, K,Digre, C,Zander, H,Ehrsson, G,David, A,Benomar, E,Nikoskelainen, Y,Trottier, G,Holmgren, L J,Ptacek, A,Anttinen, A,Brice, M,Schalling

Genome research · 1996-10-01

pmid:8908515

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)

How Early Should I Refer My Patient? The Benefits of a Quick Ophthalmic Referral in Spinocerebellar Ataxias, a Case Series and Literature Review.

Andrea B,Fiscal-Carvajal, José L,De-León-Guerra, Cristian E,Salinas-Aguirre, Marisol,Ibarra-Ramírez, Marissa L,Fernández-de-Luna, Ingrid E,Estrada-Bellmann, Joel,Arenas-Estala, Luis D,Campos-Acevedo, Jibran,Mohamed-Noriega

Brain sciences · 2026-07-17

pmid:42512530

Loss of astrocytic markers and impaired metabolic function in spinocerebellar ataxia type 7 patient-derived neural cultures.

Linde F,Bouwman, Ronald A M,Buijsen, Linda M,van der Graaf, Barry A,Pepers, Bas J B,Voesenek, Hailiang,Mei, Bart P C,van de Warrenburg, Willeke M C,van Roon-Mom

Neurobiology of disease · 2026-06-09

pmid:42264098

Metformin improves RAN protein pathology, alternative splicing, and behavioral phenotypes in SCA8 mice.

Lisa El,Romano, Setsuki,Tsukagoshi, Emily E,Davey-Osuch, Ramadan,Ajredini, Kamat,Manasi, Tala Vr,Ortiz, Eduardo,Rijos, Nathan J,Bourgon, S Elaine,Ames, Timothy J,Garrett, John D,Cleary, Eric T,Wang, Laura Pw,Ranum

Life science alliance · 2026-03-02

pmid:41771688

Unbiased human genomic characterization of polyglutamine disorder genes to guide biological understanding and therapeutic strategies.

Kevin Lucy,Namuli, Britt I,Drögemöller, Galen E B,Wright

HGG advances · 2025-11-17

pmid:41254939

The Case of Spinocerebellar Ataxias in Amazonas (Northern Brazil): An Analysis of Disease Frequency from a Geographic, Historical, and Genetic-Evolutionary Perspective.

Diana Vieira,Brito, Marcus Vinicius,Della Coletta, Giselle Benevides Monteiro,Ferreira, Sabrina Rodrigues,da Silva, Patricia Batista de,Azevedo, Cleiton,Fantin

Cerebellum (London, England) · 2025-09-03

pmid:40900235

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

A genome-wide approach for the discovery of novel repeat expansion disorders in the Undiagnosed Diseases Network cohort.

Sarah,Fazal, Harriet,Dashnow, Maike F,Dohrn, Jacquelyn,Raposo, Laurel,Hiatt, Matt C,Danzi, Isaac R L,Xu, Camilo,Toro, David R,Adams, Karen,Usdin, Bruce,Hayward, Shilpa Nadimpalli,Kobren, Shamil R,Sunyaev, Rebecca C,Spillmann, Vandana,Shashi, Adriana,Rebelo, Guney,Bademci, Mustafa,Tekin, Aaron R,Quinlan, Stephan,Zuchner

Genetics in medicine : official journal of the American College of Medical Genetics · 2025-05-22

pmid:40417743

ATXN10 Gene Expansions in Mexican Patients with Ataxia Without Epilepsy.

Aurelio,Jara-Prado, Eukeni,Arias-Capistran, Jorge,Guerrero-Camacho, Adriana,Ochoa-Morales, Marie Catherine,Boll, David,Dávila-Ortíz de Montellano, Astrid,Rasmussen, Tetsuo,Ashizawa, Juan,Fernandez-Ruiz, Petra,Yescas-Gómez, Miguel Ángel,Ramírez-García

Cerebellum (London, England) · 2025-01-16

pmid:39820777

Increased nuclear import characterizes aberrant nucleocytoplasmic transport in neurons from patients with spinocerebellar ataxia type 7.

Joshua G,Macopson-Jones, Maile,Adams, Julien,Philippe, Albert R,La Spada

Frontiers in molecular neuroscience · 2024-11-22

pmid:39649105

Locus SCA7 ATXN7

Disease

Locus

Alleles

gnomAD

References

Additional Literature