MEMSA

Overview

Myoclonic epilepsy myopathy sensory ataxia (MEMSA) is a disease which starts in childhood to late adulthood. The symptoms include problems in movement coordination, seizures and uncontrollable muscle jerks as well as a degeneration of muscles and brain dysfunctions. The disease itself is caused by a mutation in the DNA of mitochondria, which leads to a lower energy supply in the cells of the body. Treatment of MEMSA is largely supportive, including physiotherapy, speech therapy and seizure management.

 

Other names: Spinocerebellar ataxia with epilepsy (SCAE)

Sources: Genetics Home Reference (NIH), GeneReviews

Symptoms

The symptoms of MEMSA include the following

-       Cerebellar ataxia (Problems in movement coordination and balance)

-       Epilepsy (recurrent seizures)

-       Myoclonus (uncontrollable muscle jerks)

-       Encephalopathy (brain dysfunction)

-       Myopathy (muscle weakness)

 

Sources: Genetics Home Reference (NIH)

Causes

MEMSA caused by a change (mutation) in the mitochondrial DNA. Mitochondria are small structures in the cells of the body, which convert food and oxygen to energy (ATP). This energy is absolutely necessary for a proper functioning of the cell and the whole body.

In MEMSA, a gene called POLG is mutated. POLG is part of the protein polymerase, which copies the DNA of the mitochondria. With this mutation, the polymerase is less efficient in replicating the mitochondrial DNA. This leads to fewer copies of the mitochondrial DNA, thus to fewer mitochondria and less energy in cells that have a high demand in energy, like in the brain or the muscles.

 

Sources: Genetics Home Reference (NIH)

Prevention

MEMSA is an autosomal recessive disease. This means that a person does not show symptoms, if only one out of two POLG genes in the genome is mutated. To develop this disease, a child needs to inherit a mutated form of the POLG gene from both its parents.

If you know of a case of MEMSA in your family, genetic counseling might be advised if you plan to have children of your own.

 

Sources: Genetics Home Reference (NIH)

Diagnosis

To diagnose MEMSA, the mitochondrial DNA is analyzed for mutations in the POLG gene. For this molecular test, a small quantity of blood is sufficient. The biochemical analysis of muscle tissue can also be done, but is less sensitive and specific compared to the analysis of mitochondrial DNA.

Sources: GeneReviews

 

Prognosis

Not supplied.

Treatment

Treatment of MEMSA is largely supportive, limited to symptom management and involves physiotherapy, speech therapy and seizure management

Sources: GeneReviews

 

Resources

Not supplied.