What is SANDO?

Sensory ataxic neuropathy, dysarthria, and ophthalmoparesis (SANDO) is a very rare mitochondrial disease that is part of the ataxia neuropathy spectrum (ANS) typically associated with mutations in the gene POLG1. It primarily affects the brain, muscles, nerves, and eyes[1,2].

SANDO usually presents during adulthood; the mean age of onset is 32 years, although with recognition of this phenotype younger patients can be identified[3]. The symptoms caused by SANDO and their severity vary widely among individuals with the disorder. While the disorder worsens over time, its progression is slower and milder than other related mitochondrial disorders[1].

There is no cure for SANDO. Available treatments focus on symptom management and improving an individual’s quality of life. 

What causes SANDO?

SANDO is caused by inherited mutations in the POLG1 gene[1]. The most common POLG1 variants associated with SANDO are p.A467T and p.W748S (although p.A467T is not specific to SANDO)[3].

POLG1 is the gene responsible for the protein that replicates mtDNA. Mutations in this gene  reduce the amount and fidelity of mitochondrial DNA present in the cell  by compromising mitochondrial DNA maintenance[4].


What are the symptoms of SANDO?

As its full acronym suggests, the defining symptoms of SANDO are impaired coordination (ataxia), slurred speech (dysarthria), and weakness of the eye muscles (ophthalmoparesis)[2]. Most (but not all) individuals with SANDO are also at great risk of eventually experiencing brain disease with seizures[1]. The natural history of SANDO can overlap with late onset Alpers Huttenlocher syndrome.

Other symptoms of SANDO may include[1,3]:

  • hearing loss
  • drooping eyelids (ptosis)
  • weakness of the limbs
  • depression
  • migraines
  • blindness
  • liver dysfunction
  • cognitive deficits
  • heart disease
  • gastrointestinal disease

How do I know if my loved one has SANDO?

Your loved one’s healthcare provider will perform a symptom assessment and test for POLG1 mutations to establish a diagnosis of SANDO. They may also use Magnetic Resonance Imaging (MRI) or a computerized tomography (CT) scan to look for changes in the brain associated with SANDO[1].

What are the treatments for SANDO?

Unfortunately, there is no way to cure SANDO or to halt its progression. However, the following treatments can help manage symptoms and improve life for individuals and their families[1]:

  • occupational and physical therapy for impaired coordination and limb weakness
  • speech therapy for speech problems
  • anti-epileptic medications for seizures (although valproic acid and sodium divalproate must be avoided as it is associated with liver failure)

Since SANDO is an inherited disorder, genetic counseling for the family may also be recommended.


Are there any clinical trials for SANDO?

To see what trials you may qualify for, visit our Clinical Trials page – which also includes a Clinical Trials Finder Tool. We also highly encourage you to join our patient registry, mitoSHARE, where we are actively recruiting SANDO families.


How can my family cope with SANDO?

We are here to help. UMDF serves many families coping with SANDO. We suggest you reach out to our Support & Education Team – online, via email at support@umdf.org, or phone at (888) 900-6486 – who can suggest a host of resources including doctors, disease or region specific support meetings, and more. They’ll also connect you with a UMDF ambassador, who will be fellow SANDO patient or family member if possible, who can help support and guide you through your questions.



What are the next steps if my loved one has SANDO?

  • Get Support
    Connect with our Support & Education Team online, via email at support@umdf.org or phone at (888) 900-6486.
  • Check our Clinical Trials Finder
    Use our Clinical Trials Finder to see if you qualify for any clinical trials.
  • Join our patient registry, mitoSHARE
    We are actively recruiting SANDO families to participate in our patient registry, mitoSHARE. Patient registries like mitoSHARE are an integral part in charting a course toward treatments and cures for SANDO and other mitochondrial diseases. There are currently over 30 active mitochondrial disease clinical trials. Next generation patient registries like mitoSHARE are an integral part of expanding that number.
  • Become an advocate
    Ask your representatives to prioritize mitochondrial disease research and support via the UMDF Advocacy Center. We’ll send regular action items so you – and your friends and family – can let Congress know where we need their support. Click here to sign up.

What is UMDF doing about SANDO?

UMDF is helping chart a path toward treatments and eventual cure of mitochondrial diseases like SANDO through:

  • Research & Funding: UMDF has provided more than $15 million in research funding to find treatments for diseases like SANDO. UMDF advocacy has helped secure an additional $55 million in federal funding via the Department of Defense and National Institutes of Health.
  • Data: Over two decades ago, UMDF pioneered patient registries for the mitochondrial disease community. Today, our next generation patient registry, mitoSHARE, is helping chart a path toward the treatment and eventual cure of mitochondrial diseases.
  • Patient Support: Thousands of families just like you depend upon UMDF for support and education on diseases like SANDO. Attendance at our support meetings annually tops 7,000, including disease specific support meetings for families.
  • Clinician Support: To help educate clinicians on diseases like SANDO, we feature monthly Bench to Bedside clinician seminars, host the annual Mitochondrial Medicine Symposium, support the Mitochondrial Care Network, and educate clinicians on our Mito U platform.

I didn’t find what I’m looking for here. What should I do?

UMDF Is here to help. Contact the Support Line at (888) 900-6486 weekdays from 8:00am to 5:00pm EST to connect with our Patient Concierge. Or, via email contact support@umdf.org.


  1. Cohen BH, Chinnery PF, Copeland WC. POLG-Related Disorders. 2010 Mar 16 [Updated 2018 Mar 1]. In: Adam MP, Everman DB, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2022. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26471/
  1. Fadic R, Russell JA, Vedanarayanan VV, Lehar M, Kuncl RW, Johns DR. Sensory ataxic neuropathy as the presenting feature of a novel mitochondrial disease. Neurology. 1997;49(1):239-245. doi:10.1212/wnl.49.1.239
  1. Li LX, Jiang LT, Pan YG, et al. Clinical and Molecular Features of POLG-Related Sensory Ataxic Neuropathy with Dysarthria and Ophthalmoparesis. J Mol Neurosci. 2021;71(12):2462-2467. doi:10.1007/s12031-021-01831-9
  1. Copeland WC. Defects in mitochondrial DNA replication and human disease. Crit Rev Biochem Mol Biol. 2012;47(1):64-74. doi:10.3109/10409238.2011.632763