Diagnosis
Classification
A few SCAs remain unspecified and can not be precisely diagnosed, but in the last decade genetic testing has allowed precise identification of dozens of different SCAs  and more tests are being added each year. In 2008, a genetic ataxia blood test developed to test for 12 types of SCA, Friedreichs ataxia, and several others. However, since not every SCA has been genetically identified some SCAs are still diagnosed  by neurological examination, which  may include a physical exam, family history, MRI scanning of the brain and spine, and spinal tap.Many SCAs below fall under the category of polyglutamine diseases, which are caused when a disease-associated protein (i.e., ataxin-1, ataxin-3, etc.) contains a large number of repeats of glutamine residues, termed a polyQ sequence or a "CAG trinucleotide repeat" disease for either the one-letter designation or codon for glutamine respectively. The threshold for symptoms in most forms of SCA is around 35, though for SCA3 it extends beyond 50. Most polyglutamine diseases are dominant due to the interactions of resulting polyQ tail.The first ataxia gene was identified in 1993 and called "Spinocerebellar ataxia type 1" (SCA1); later genes were called SCA2, SCA3, etc. Usually, the "type" number of "SCA" refers to the order in which the gene was found. At this time, there are at least 29 different gene mutations that have been found.The following is a list of some of the many types of Spinocerebellar ataxia. Others include SCA18, SCA20, SCA21, SCA23, SCA26, SCA28, and SCA29.
Four X-linked types have been described ( 302500,  302600,  301790,  301840), but only the first of these has so far been tied to a gene (SCAX1). Treatment
Medication
There is no cure for spinocerebellar ataxia, which is currently considered to be a progressive and irreversible disease, although not all types cause equally severe disability.In general, treatments are directed towards alleviating symptoms, not the disease itself. Many patients with hereditary or idiopathic forms of ataxia have other symptoms in addition to ataxia. Medications or other therapies might be appropriate for some of these symptoms, which could include tremor, stiffness, depression, spasticity, and sleep disorders, among others. Both onset of initial symptoms and duration of disease are variable. If the disease is caused by a polyglutamine trinucleotide repeat CAG expansion, a longer expansion may lead to an earlier onset and a more radical progression of clinical symptoms. Typically, a person with this disease will eventually be unable to perform daily tasks (ADLs). However, rehabilitation therapists can help patients to maximize their ability of self-care and delay deterioration to certain extent. Researchers are exploring multiple avenues for a cure including RNAi and the use of Stem Cells and several other avenues.On January 18, 2017, BioBlast Pharma announced completion of Phase 2a clinical trials of their medication, Trehalose, in the treatment of SCA3. BioBlast has received FDA Fast Track status and Orphan Drug status for their treatment.