autosomal recessive spinocerebellar ataxia 10

Autosomal recessive spinocerebellar ataxia 10 (SCAR10) is a neurological condition that primarily affects the cerebellum, the part of the brain responsible for balance, coordination, and smooth movement. It is caused by disease-causing variants in the ANO10 gene, which encodes a protein thought to help regulate ion flow in nerve cells. Symptoms typically emerge in late childhood or adulthood and gradually interfere with walking, speech, and precise movements. SCAR10 affects fewer than one in a million people worldwide, making it an ultra-rare diagnosis. Severity and symptoms vary widely between individuals, even among siblings with the same genetic change.

SCAR10 first draws attention through neurological problems. Most individuals develop gait ataxia, limb incoordination, and slurred speech (dysarthria) as the earliest and most recognizable signs. Brain imaging often shows cerebellar atrophy, helping to explain these movement difficulties. Over time, exaggerated reflexes in the knees and ankles, intention tremor, and an up-and-down (downbeat) nystagmus of the eyes can appear, further affecting balance and vision. Eye-movement abnormalities such as hypermetric or slow saccades and tortuous conjunctival vessels are common and may be noticed during a neuro-ophthalmologic examination. Less frequently, individuals experience pes cavus (high-arched feet), fasciculations, or a positive Babinski sign. A minority also show mild intellectual disability or other cognitive concerns, underscoring that SCAR10 is not solely a movement disorder but can involve broader neurological development. Not all individuals experience every feature, and the pace of progression differs considerably from person to person.

SCAR10 results from pathogenic variants in the ANO10 gene. The ANO10 protein is believed to act as an ion channel regulator in many tissues, including the cerebellum, so loss of its normal function disrupts neuronal signaling and coordination. The condition follows an autosomal recessive inheritance pattern, meaning a person must inherit two altered copies of ANO10 (one from each parent) to be affected. Parents who each carry one altered copy are typically healthy but have a 25 percent chance with each pregnancy of having a child with SCAR10. Because this condition is very rare, it is more likely to appear in families where parents share a common ancestor, which increases the chance that both carry the same rare variant. Genetic counseling can help relatives understand carrier testing options and family-planning choices.

Currently, management focuses on supportive care and symptom management. Physical and occupational therapy help maintain mobility and compensate for coordination difficulties, while speech therapy can improve clarity of speech and swallowing safety. Medications may be used off-label to lessen tremor or muscle stiffness, guided by a neurologist. Regular surveillance is an essential part of long-term care, helping to identify potential complications before they become serious. Neurological follow-up, periodic eye examinations to monitor nystagmus, and orthopedic assessment for foot deformities are typical components of care. Because individual needs change over time, treatment is best coordinated by a multidisciplinary team that may include neurologists, physiatrists, rehabilitation specialists, and genetic counselors. Patients should discuss management options with their healthcare team to determine which approaches are most appropriate for their situation.

Long-term outcomes for SCAR10 have not been fully defined because only a small number of individuals are reported in the medical literature. Most people experience slow progression of balance and coordination problems, and some eventually need walking aids or a wheelchair for long distances. Cognitive changes, when present, are usually mild, but they can add to daily challenges. Outcomes described in medical literature continue to evolve as standards of care improve. Access to early rehabilitation services, adaptive equipment, and ongoing neurological surveillance can make a meaningful difference in maintaining independence and quality of life. Families often find it helpful to connect with specialists familiar with hereditary ataxias and with genetic counselors who can guide family planning and provide resources for support.

Clinical trials are underway exploring new treatment approaches for inherited cerebellar ataxias, including SCAR10. Individuals interested in participating can search ClinicalTrials.gov or consult their care team about eligibility.