Spinocerebellar Ataxia 8 (ATXN8)
| Dred_ID | RD00010 |
| OMIM ID | 608768 |
| Disease name | Spinocerebellar Ataxia 8 |
| Alternative names | SCA8 |
| Category | Genetic diseases, Rare diseases, Neuronal diseases, Skin diseases, Eye diseases, Mental diseases, Ear diseases, Metabolic diseases, Fetal diseases, Liver diseases |
| Phenotype | NIH Rare Diseases: Spinocerebellar ataxia type 8 (SCA8) is an inherited neurodegenerative condition characterized by slowly progressive ataxia (problems with movement, balance, and coordination). This condition typically occurs in adulthood and usually progresses over decades. Common initial symptoms include dysarthria, slow speech, and trouble walking. Some affected individuals experience nystagmus and other abnormal eye movements. Life span is typically not shortened. This condition is inherited in an autosomal dominant manner, although not all individuals with abnormalities in the disease-causing gene will develop the disease (called reduced penetrance).
OMIM: SCA8 is a slowly progressive ataxia with disease onset typically occurring in adulthood. Onset ranges from age one to 73 years. The progression is typically over decades regardless of the age of onset. Common initial symptoms are scanning dysarthria with a characteristic drawn-out slowness of speech and gait instability; life span is typically not shortened. Some individuals present with nystagmus, dysmetric saccades and, rarely, ophthalmoplegia. Tendon reflex hyperreflexity and extensor plantar responses are present in some severely affected individuals. Life span is typically not shortened. |
| Miscellaneouse | OMIM： onset between 18 and 65 years sca8 is caused by bidirectional transcription on chromosome 13q21 involving complementary repeat expansion in atxn8 and atxn8-opposite strand normal alleles contain 15 to 50 repeats pathogenic alleles contain 71 to 1,300 repeats |
| Prevalence | N/A [source: MalaCards] |
| Inheritance | autosomal dominant |
| Anticipation | Yes |
| Evidence | Strong |
| Gene symbol | ATXN8 |
| Alias symbols | Ataxin 8 |
| Gene name | Ataxin 8 |
| Gene map locus | 13q21 |
| Ensembl Gene ID | N/A |
| Gene expression and Gene Ontology | BioGPS |
| Protein expression | Human Protein Atlas |
| Gene sequence | Sequence |
| Variation | ClinVar, dbSNP | Gene conservation | Gene Conservation from UCSC Genome Browser |
| Gene Description | ATXN8 was translated into protein, which was predicted to contain an initiating methionine followed by a polyglutamine repeat broken only by 2 arg residues near its C terminus. [supplied by OMIM, Mar 2010] |
| Repeat unit | CAG |
| Normal repeat copies | 15-50 |
| Pathogenic repeat copies | ≥71 |
| Gene | ATXN8 |
| Repeat location | CDS |
| Chromosome locus | NULL |
| Repeat conservation | Repeat Conservation from UCSC Genome Browser |
| Toxic cause | Protein |
| Possible toxicity | Spinocerebellar ataxia-8 is a neurodegenerative disorder caused by a CTG/CAG trinucleotide repeat expansion on chromosome 13q21. Two genes span the CTG/CAG repeat and are expressed in opposite directions: ATXN8, which encodes a nearly pure polyglutamine expansion protein in the CAG direction, and ATXN8OS (603680), which, when transcribed, produces a noncoding CUG expansion RNA. |
| Pathway annotation | Reactome, KEGG |
| PMID | 16804541 |
| Authors | Moseley ML, Zu T, Ranum LPW |
| Title | Bidirectional expression of CUG and CAG expansion transcripts and intranuclear polyglutamine inclusions in spinocerebellar ataxia type 8 |
| Journal | Nature Genetics |
| Year | 2006 |