Clinical diagnosis is conducted on individuals with age onset between late teens and late forties who show the initial characteristics for the recessive autosomal cerebellar ataxia.

The following tests are performed:

- MRI brain screening for cerebellum atrophy.

- Molecular genetic testing for SYNE-1 sequence analysis.

- Electrophysiologic studies for polyneurotherapy

- Neurological examination

Prenatal diagnosis and preimplantation genetic diagnosis (PGD) can be performed to identify the mothers carrying the recessive genes for cerebellar ataxia.

Different types of ataxia:

- congenital ataxias (developmental disorders)

- ataxias with metabolic disorders

- ataxias with a DNA repair defect

- degenerative ataxias

- ataxia associated with other features.

A diagnosis of Friedreich's ataxia requires a careful clinical examination, which includes a medical history and a thorough physical exam, in particular looking for balance difficulty, loss of proprioception, absence of reflexes, and signs of neurological problems. Genetic testing now provides a conclusive diagnosis. Other tests that may aid in the diagnosis or management of the disorder include:

- Electromyogram (EMG), which measures the electrical activity of muscle cells,

nerve conduction studies, which measure the speed with which nerves transmit impulses

- Electrocardiogram (ECG), which gives a graphic presentation of the electrical activity or beat pattern of the heart

- Echocardiogram, which records the position and motion of the heart muscle

- Blood tests to check for elevated glucose levels and vitamin E levels

- Magnetic resonance imaging (MRI) or computed tomography (CT) scans, tests which provide brain and spinal cord images that are useful for ruling out other neurological conditions

There is no known prevention of spinocerebellar ataxia. Those who are believed to be at risk can have genetic sequencing of known SCA loci performed to confirm inheritance of the disorder.

In diagnosing autosomal dominant cerebellar ataxia the individuals clinical history or their past health examinations, a current physical examination to check for any physical abnormalities, and a genetic screening of the patients genes and the genealogy of the family are done. The large category of cerebellar ataxia is caused by a deterioration of neurons in the cerebellum, therefore magnetic resonance imaging (MRI) is used to detect any structural abnormality such as lesions which are the primary cause of the ataxia. Computed tomography (CT) scans can also be used to view neuronal deterioration, but the MRI provides a more accurate and detailed picture.

MJD can be diagnosed by recognizing the symptoms of the disease and by taking a family history. Physicians ask patients questions about the kind of symptoms relatives with the disease had, the progression and harshness of symptoms, and the ages of onset in family members.

Presymptomatic diagnosis of MJD can be made with a genetic test. The direct detection of the genetic mutation responsible for MJD has been available since 1995. Genetic testing looks at the number of CAG repeats within the coding region of the MJD/ATXN3 gene on chromosome 14. The test will show positive for MJD if this region contains 61-87 repeats, as opposed to the 12-44 repeats found in healthy individuals. A limitation to this test is that if the number of CAG repeats in an individual being tested falls between the healthy and pathogenic ranges (45-60 repeats), then the test cannot predict whether an individual will have MJD symptoms.

Diagnosis of MSA can be challenging because there is no test that can definitively make or confirm the diagnosis in a living patient. Clinical diagnostic criteria were defined in 1998 and updated in 2007. Certain signs and symptoms of MSA also occur with other disorders, such as Parkinson's disease, making the diagnosis more difficult.

Both MRI and CT scanning frequently show a decrease in the size of the cerebellum and pons in those with cerebellar features. The putamen is hypodense on T2-weighted MRI and may show an increased deposition of iron in Parkinsonian form. In cerebellar form, a "hot cross" sign has been emphasized; it reflects atrophy of the pontocereballar fibers that manifest in T2 signal intensity in atrophic pons.

A definitive diagnosis can only be made pathologically on finding abundant glial cytoplasmic inclusions in the central nervous system.

Diffuse, symmetric white matter abnormalities were demonstrated by magnetic resonance imaging (MRI) suggesting that Behr syndrome may represent a disorder of white matter associated with an unknown biochemical abnormality.

Diagnosis is suspected clinically and family history, neuroimaging and genetic study helps to confirm Behr Syndrome.

In terms of a cure there is currently none available, however for the disease to manifest itself, it requires mutant gene expression. Manipulating the use of protein homoestasis regulators can be therapuetic agents, or a treatment to try and correct an altered function that makes up the pathology is one current idea put forth by Bushart, et al. There is some evidence that for SCA1 and two other polyQ disorders that the pathology can be reversed after the disease is underway. There is no effective treatments that could alter the progression of this disease, therefore care is given, like occupational and physical therapy for gait dysfunction and speech therapy.

There are five sub-types of MJD that are characterized by the age of onset and range of symptoms.

The sub-types illustrate a wide variety of symptoms that patients can experience. However, assigning individuals to a specific sub-type of the disease is of limited clinical significance.

- Type I is distinguished by arrival between the ages of 10 and 30 and represents approximately 13% of individuals. It usually has fast development and severe rigidity and dystonia.

- Type II is the most common sub-type (approximately 57% of individuals with MJD ) and typically begins between 20 and 50 years of age . It has an intermediate progression and causes symptoms that include spasticity, exaggerated reflex responses and spastic gait, ataxia and upper motor neuron signs.

- Type III MJD has a slow progression. Patients typically have an onset between the ages of 40 and 70 and represent approximately 30% of MJD patients. Symptoms include muscle twitching, tingling, cramps, unpleasant sensations such as numbness, pain in the feet, hands and limbs and muscle atrophy. Nearly all patients experience a decline in their vision such as blurred vision, double vision, inability to control eye movements, and loss of capability to distinguish color. Some patients also experience Parkinsonian symptoms.

- Type IV is distinguished by Parkinsonian symptoms that respond particularly well to levodopa treatment.

- Type V appears to resemble Hereditary Spastic Paraplegia; however, more research is needed to conclude the relationship between Type V MJD and hereditary spastic paraplegia.

There is currently no cure for SCA 6; however, there are supportive treatments that may be useful in managing symptoms.

There is no known prevention of spinocerebellar ataxia. Those who are believed to be at risk can have genetic sequencing of known SCA loci performed to confirm inheritance of the disorder.

Neuroimaging like MRI is important. However, there was considerable intrafamilial variability regarding neuroimaging, with some individuals showing normal MRI findings. Early individual prognosis of such autosomal recessive cerebellar ataxias is not possible from early developmental milestones, neurological signs, or neuroimaging.

Prenatal screening is not typically done for FHM, however it may be performed if requested. As penetrance is high, individuals found to carry mutations should be expected to develop signs of FHM at some point in life.

Blood lactate and pyruvate levels usually are elevated as a result of increased anaerobic metabolism and a decreased ratio of ATP:ADP. CSF analysis shows an elevated protein level, usually >100 mg/dl, as well as an elevated lactate level.

There is no cure or treatment for GSS. It can, however, be identified through genetic testing. GSS is the slowest to progress among human prion diseases. Duration of illness can range from 3 months to 13 years, with an average duration of 5 or 6 years.

It is not necessary to biopsy an ocular muscle to demonstrate histopathologic abnormalities. Cross-section of muscle fibers stained with Gömöri trichrome stain is viewed using light microscopy. In muscle fibers containing high ratios of the mutated mitochondria, there is a higher concentration of mitochondria. This gives these fibers a darker red color, causing the overall appearance of the biopsy to be described as "ragged red fibers. Abnormalities may also be demonstrated in muscle biopsy samples using other histochemical studies such as mitochondrial enzyme stains, by electron microscopy, biochemical analyses of the muscle tissue (ie electron transport chain enzyme activities), and by analysis of muscle mitochondrial DNA. "

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 afflicted 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. The information provided by BioBlast in their research indicates that they hope this treatment may prove efficacious in other SCA treatments that have similar pathology related to PolyA and PolyQ diseases.

In addition, Dr. Beverly Davidson has been working on a methodology using RNAi technology to find a potential cure for over 2 decades. Her research began in the mid-1990s and progressed to work with mouse models about a decade later and most recently has moved to a study with non-human primates. The results from her most recent research "are supportive of clinical application of this gene therapy". Dr. Davidson along with Dr. Pedro Gonzalez-Alegre are currently working to move this technique into a Phase 1 clinical trial.

Finally, another gene transfer technology discovered in 2011 has also been shown by Dr. Davidson to hold great promise and offers yet another avenue to a potential future cure.

Diagnosis of Jansky–Bielschowsky disease is increasingly based on assay of enzyme activity and molecular genetic testing. Thirteen pathogenic candidate genes—PPT1, TPP1, CLN3, CLN5, CLN6, MFSD8, CLN8, CTSD, DNAJC5, CTSF, ATP13A2 GRN, KCTD7—are associated with the development of the disease. Patients with Jansky–Bielschowsky disease typically have up to 50% reduced lysosomal enzymes, and thus an enzyme activity assay is a quick and easy diagnostic test.

Vision impairment is an early symptom of Jansky–Bielschowsky disease, and so an eye exam is another common diagnostic tool. During the eye exam, loss of cells within the eye would indicate the presence of the disease however more tests are needed for a complete diagnosis.

Other common diagnostic tests include:

- Blood or urine test: Elevated levels of the chemical dolichol found in the urine is typical of individuals with the disease, as well as the presence of vacuolated lymphocytes in the blood.

- Skin or tissue sampling: Microscopy of skin could be used to observe lipopigment aggregation.

- CT scan or MRI: Visualization of the brain would be able to detect areas of cerebral atrophy.

RG2833, a histone deacetylase inhibitor developed by Repligen, was acquired by BioMarin Pharmaceutical in January 2014. The first human trials with this compound began in 2012.

Horizon Pharma's development plan of interferon gamma-1B for treatment of FA was given fast track designation by the Food and Drug Administration in 2015.

In its trials released in December 2016, however, the results showed no improvements over placebo in patients.

Diagnosis of FHM is made according to the following criteria:

- Two attacks of each of the following:

- At least one close (first or second degree) relative with FHM

- No other likely cause

Sporadic forms follow the same diagnostic criteria, with the exception of family history.

In all cases, family and patient history is used for diagnosis. Brain imaging techniques, such as MRI, CAT scans and SPECT, are used to look for signs of other familial conditions such as CADASIL or mitochondrial disease, and for evidence of cerebellar degeneration. With the discovery of causative genes, genetic sequencing can also be used to verify diagnosis (though not all genetic loci are known).

The diagnosis of A-T is usually suspected by the combination of neurologic clinical features (ataxia, abnormal control of eye movement, and postural instability) with telangiectasia and sometimes increased infections, and confirmed by specific laboratory abnormalities (elevated alpha-fetoprotein levels, increased chromosomal breakage or cell death of white blood cells after exposure to X-rays, absence of ATM protein in white blood cells, or mutations in each of the person’s ATM genes).

A variety of laboratory abnormalities occur in most people with A-T, allowing for a tentative diagnosis to be made in the presence of typical clinical features. Not all abnormalities are seen in all patients. These abnormalities include:

- Elevated and slowly increasing alpha-fetoprotein levels in serum after 2 years of age

- Immunodeficiency with low levels of immunoglobulins (especially IgA, IgG subclasses, and IgE) and low number of lymphocytes in the blood

- Chromosomal instability (broken pieces of chromosomes)

- Increased sensitivity of cells to x-ray exposure (cells die or develop even more breaks and other damage to chromosomes)

- Cerebellar atrophy on MRI scan

The diagnosis can be confirmed in the laboratory by finding an absence or deficiency of the ATM protein in cultured blood cells, an absence or deficiency of ATM function (kinase assay), or mutations in both copies of the cell’s ATM gene. These more specialized tests are not always needed, but are particularly helpful if a child’s symptoms are atypical.

Physical therapists can assist patients in maintaining their level of independence through therapeutic exercise programmes. One recent research report demonstrated a gain of 2 SARA points (Scale for the Assessment and Rating of Ataxia) from physical therapy. In general, physical therapy emphasises postural balance and gait training for ataxia patients. General conditioning such as range-of-motion exercises and muscle strengthening would also be included in therapeutic exercise programmes. Research showed that spinocerebellar ataxia 2 (SCA2) patients with a mild stage of the disease gained significant improvement in static balance and neurological indices after six months of a physical therapy exercise training program. Occupational therapists may assist patients with incoordination or ataxia issues through the use of adaptive devices. Such devices may include a cane, crutches, walker, or wheelchair for those with impaired gait. Other devices are available to assist with writing, feeding, and self care if hand and arm coordination are impaired. A randomised clinical trial revealed that an intensive rehabilitation program with physical and occupational therapies for patients with degenerative cerebellar diseases can significantly improve functional gains in ataxia, gait, and activities of daily living. Some level of improvement was shown to be maintained 24 weeks post-treatment. Speech language pathologists may use both behavioral intervention strategies as well as augmentative and alternative communication devices to help patients with impaired speech.

MSA usually progresses more quickly than Parkinson's disease. There is no remission from the disease. The average remaining lifespan after the onset of symptoms in patients with MSA is 7.9 years. Almost 80% of patients are disabled within five years of onset of the motor symptoms, and only 20% survive past 12 years. Rate of progression differs in every case and speed of decline may vary widely in individual patients.

O’Sullivan and colleagues (2008) identified early autonomic dysfunction to be the most important early clinical prognostic feature regarding survival in MSA. Patients with concomitant motor and autonomic dysfunction within three years of symptom onset had a shorter survival duration, in addition to becoming wheelchair dependent and bed-ridden at an earlier stage than those who developed these symptoms after three years from symptom onset. Their study also showed that when patients with early autonomic dysfunction develop frequent falling, or wheelchair dependence, or severe dysphagia, or require residential care, there is a shorter interval from this point to death.