Last updated:
12/23/2025
Years published: 2025
NORD gratefully acknowledges Haiyun Kong, Master of Health Administration candidate at Columbia University; Allison Gregory, MS, CGC, Associate Professor and Genetic Counselor, NBIA Center of Excellence/Hayflick Lab, Oregon Health & Science University; and Gioconda Alyea, MD (FMG), MS, National Organization for Rare Disorders, for the preparation of this report.
Summary
MECR-related neurologic disorder is an ultra-rare genetic condition that mainly affects movement and vision.
The first sign is usually an involuntary movement disorder, meaning the body makes movements that the child cannot control, and it usually begins between ages 1 and 6.1, 2 The most common symptom is dystonia, which causes muscles to tighten or twist involuntarily. Some children present with a different movement disorder known as chorea, characterized by quick, jerky movements, or ataxia, which affects balance and coordination. Many children eventually need help with mobility, such as walkers or wheelchairs. 2
Speech difficulties are also common and often worsen over time. Speech often becomes progressively harder to understand because of difficulty forming words (dysarthria) expressed as slurring, mumbling, slow, garbled or quiet speech.1
Vision problems usually appear a few years after the movement problems begin, most often between ages 4 and 12.1 These problems are due to optic atrophy, which is damage to the optic nerve, which transmits visual information from the eye to the brain. This can cause major vision loss and sometimes leads to legal blindness in adulthood.
Cognitive abilities are usually normal, although some individuals may have challenges with language or executive functioning (focusing attention, controlling impulses, planning and organizing, remembering instructions, solving problems, and managing emotions). 2 Symptoms can get worse during a fever or illness, and some children may not fully regain the skills they lose during these episodes. 1,2
Symptoms usually start in childhood, but recent reports show they can also begin in adulthood as isolated optic neuropathy (damage to the optic nerve that can cause pain and vision loss) without dystonia (involuntary muscle contractions such as tightening or twisting) or other childhood movement problems, which widens the known range of symptoms.3, 4
MECR-related neurologic disorder is caused by disease-causing changes (pathogenic variants) in the MECR gene. This gene plays an important role in producing mitochondrial fatty acids and lipoic acid, which help the body produce energy.1, 5, 6 When both copies of the MECR gene have these changes, cells, especially in the brain and optic nerve, cannot produce energy normally. This leads to problems with movement, speech, and vision.
The condition is inherited in an autosomal recessive manner (An individual must inherit two copies of the gene that has the variant for the disorder to develop.). 1 Fewer than 20 affected individuals have been described in academic papers worldwide, 1,2, 3, 4 but the MEPAN Foundation reports being aware of over 30 affected individuals (www.mepan.org).
There is no cure at this time. Treatment focuses on supportive care, including therapies to help with mobility, communication, and vision.1
Because this disorder was first reported in 2016 2 and very few individuals have been identified so far, it is likely that the spectrum of disease (the range of symptoms and severity) will continue to expand.
MEPAN
MEPAN, which makes up most of MECR-related neurologic disorder, is a progressive neurologic condition that begins in early childhood. The main features are movement disorder and vision loss due to optic atrophy (damage to the optic nerve, which transmits visual information from the eye to the brain). Intellectual abilities are often preserved but can vary.
Symptoms may worsen during fever or other illness, and some children do not fully regain lost skills after these episodes.1,2 Reported signs and symptoms include:
Cognition is usually normal, but some affected individuals may have difficulties with language or executive functioning (focusing attention, controlling impulses, planning and organizing, remembering instructions, solving problems, and managing emotions).2
Seizures or encephalopathy (a general term for brain dysfunction) have not been reported. Brain MRI (magnetic resonance imaging) scans often show changes in a collection of deep brain structures called the basal ganglia, which help control movement (bilateral bright T2 signal abnormalities in the basal ganglia).1
Adult-onset Optic Atrophy
Although childhood onset with combined movement disorder and optic atrophy (damage to the optic nerve, which transmits visual information from the eye to the brain) represents the typical presentation of this condition, recent reports show that it can be more variable. There are a few reports of adult-onset isolated optic neuropathy, without dystonia (involuntary muscle contractions such as tightening or twisting) or other movement symptoms.
MECR-related neurologic disorder is caused by changes in the MECR gene. This gene provides instructions for making the MECR enzyme that works inside the cell structure known as mitochondria. The MECR enzyme is required for a metabolic process called mitochondrial fatty acid synthesis (mtFAS).2 This process helps make important fatty acids and also produces lipoic acid, a molecule needed for several key energy-producing reactions inside cells.
When both copies of the MECR gene have changes that affect how the enzyme functions:
Over time, this leads to problems with movement, speech, and vision.
Studies suggest that reduced MECR enzyme activity disrupts normal mitochondrial protein assembly and energy production, which affects brain and optic nerve cells most strongly.1 ,5, 6
Inheritance
MECR-related neurologic disorder is inherited in an autosomal recessive fashion.1 This means a child must inherit two disease-causing variant (one from each parent) to be affected.
Parents with one working copy and one altered copy are carriers and typically have no symptoms. For each pregnancy between two carriers, there is a:
These chances are the same whether the developing baby is male or female.
MECR-related neurologic disorder is extremely rare, and the exact number of affected individuals worldwide is not known. As of 2025, fewer than 20 individuals have been described in the medical literature.1, 2, 3, 4 The MEPAN Foundation reports being aware of at least 30 affected individuals.
Some families reported in the literature are of Ashkenazi Jewish ancestry, where two MECR gene variants are more common. However, cases have also been identified in individuals from other ethnic backgrounds, and the condition can occur in any population.
Doctors may suspect MECR-related neurologic disorder when a child has early-onset movement problems and later development of optic atrophy (damage to the optic nerve, which transmits visual information from the eye to the brain). The combination of dystonia (involuntary muscle contractions such as tightening or twisting) beginning in early childhood, gradually worsening speech, and progressive vision loss can point toward this condition.1
Clinical features that raise suspicion may include:1
Diagnosis is confirmed through genetic testing. This can involve tests that look at one specific gene (single-gene testing) or a group of genes that are linked to the person’s symptoms (multigene panel). These are called gene-targeted tests. Often, doctors may use broader tests that scan large sections of a person’s DNA, or even their entire genetic code, to search for the cause. These are called comprehensive genomic tests. The choice of test depends on the person’s signs and symptoms.1
There are currently no proven treatments that treat the underlying cause of MECR-related neurologic disorder. ¹ Based on what is known about how the MECR enzyme works, supplements such as lipoic acid and octanoic acid have been suggested as possible treatments. This approach has been tried in one individual, with reported improvement. 2 Families interested in this type of supplementation should only consider it in close partnership with their treating physicians, since no clinical trials have been done to study these compounds in this population.
Standard care focuses on managing symptoms, supporting daily activities, and maintaining movement and communication. Most affected individuals are cared for by several different specialists, with one provider ideally helping to coordinate care and communication among the team. These specialists may include:
Children who develop vision loss from optic atrophy (damage to the optic nerve, which transmits visual information from the eye to the brain) may benefit from visual aids such as glasses or magnifiers, along with regular visits to an eye specialist to monitor changes in vision.¹
To support mobility and physical function, physical and occupational therapy are essential for helping children stay active and preventing secondary complications. Physical therapy helps maintain range of motion, and occupational therapy supports daily living skills like dressing or feeding. As symptoms progress, braces, walkers, or wheelchairs may be needed to promote safety and independence.¹
Speech difficulties caused by dysarthria (difficulty forming words) can be addressed through speech therapy. Some individuals may also benefit from augmentative and alternative communication devices, which provide other ways to communicate when speaking becomes difficult.¹
Several medications may help reduce dystonia (involuntary muscle contractions such as tightening or twisting). These include anticholinergic agents, baclofen, and benzodiazepines. Each has different potential side effects, for example, benzodiazepines may cause sedation. When oral medications can no longer provide adequate dystonia control, deep brain stimulation (DBS) could be considered in some situations. DBS delivers electrical stimulation to targeted regions of the brain using a surgically implanted electrode and battery pack. Treatment with DBS has been reported in two children with MEPAN, with improvement in dystonia lasting up to one year after surgery.7 These treatments may help manage symptoms, but they do not slow the overall progression of the condition.
Genetic counseling is recommended for families. A genetic counselor can explain the autosomal recessive inheritance pattern, identify other family members who may be affected by the diagnosis or may be carriers, discuss the chances of recurrence in future pregnancies and review options for carrier testing or prenatal testing.¹
Information on current clinical trials is posted on the Internet at https://clinicaltrials.gov/. All studies receiving U.S. Government funding, and some supported by private industry, are posted on this government web site.
For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:
Toll-free: (800) 411-1222
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Email: [email protected]
Some current clinical trials also are posted on the following page on the NORD website:
https://rarediseases.org/living-with-a-rare-disease/find-clinical-trials/
For information about clinical trials sponsored by private sources, contact:
https://www.centerwatch.com/
For information about clinical trials conducted in Europe, contact:
https://www.clinicaltrialsregister.eu/
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