Some genetic conditions are so rare that families can wait years for a name that explains what they are seeing in their child. MECR-related neurologic disorder is one of them. You may also see it called MEPAN syndrome, short for mitochondrial enoyl CoA reductase protein-associated neurodegeneration. In this post, we explain what the condition is, how it is inherited and diagnosed, and how genetic counselling can support families.
What is MECR-related neurologic disorder?
MECR-related neurologic disorder is an ultra-rare genetic condition that mainly affects movement and vision. It was first described in 2016, and only a small number of people have been reported worldwide, although patient organisations are aware of more affected individuals than appear in the medical literature.
The condition is caused by changes in the MECR gene. This gene gives instructions for an enzyme that carries out the final step of fatty acid production inside the mitochondria, the energy-producing parts of our cells. When this enzyme does not work properly, nerve cells, which have very high energy needs, are especially affected.
Signs and symptoms
Symptoms usually begin in early childhood and can include:
- Delays in reaching motor milestones in the first year of life
- A progressive movement disorder, usually starting between ages 1 and 6, most often dystonia (involuntary muscle contractions that cause twisting movements or unusual postures), sometimes alongside chorea or ataxia
- Difficulty with speech
- Optic atrophy, which is damage to the optic nerve that affects vision, typically developing between ages 4 and 12
Importantly, intellect is often, though not always, preserved. A brain MRI may show characteristic changes in an area called the basal ganglia.
Not everyone follows this classic pattern. One person has been reported with vision loss in adolescence but no movement disorder, a reminder that we are still learning about the full range of this condition.
How is it inherited?
MECR-related neurologic disorder is inherited in an autosomal recessive way. This means a person needs a change in both copies of the MECR gene to be affected. People with one changed copy are called carriers. Carriers are usually healthy and often have no idea they carry the change.
When both parents are carriers, each pregnancy has a 25% chance of the child being affected, a 50% chance of the child being a carrier, and a 25% chance of the child inheriting two working copies. The condition appears to be more common in people of Ashkenazi Jewish ancestry, but it has been found in families from many backgrounds.
How is it diagnosed?
Diagnosis is confirmed by genetic testing that finds two disease-causing changes in the MECR gene. Because the condition was only recently recognised, some older gene panels for dystonia may not include MECR. Broader testing, such as exome or genome sequencing, can be helpful when a child has unexplained dystonia and vision changes.
Treatment and management
There is currently no cure or standard treatment. Care focuses on managing symptoms and supporting quality of life, usually through a team that may include a neurologist, ophthalmologist, physiotherapist, occupational therapist, and speech pathologist. Medications can help with dystonia, and deep brain stimulation has been explored in a small number of people. Research into this condition is ongoing, and family-led groups such as the MEPAN Foundation are helping to drive it forward.
How genetic counselling can help
A rare diagnosis can feel isolating. A genetic counsellor can help you understand test results, explain what they mean for your child and your wider family, and talk through options for future pregnancies, including carrier testing, preimplantation genetic testing (PGT) and prenatal testing. We can also help connect you with support networks.
At Rosalind Genetics, we see clients via telehealth, so we can support families from anywhere in Australia. You can self-refer, and we will ask you to obtain a referral from your doctor. If MECR-related neurologic disorder has touched your family, we are here to help you make sense of it.
