The primary features displayed on a person with MERRF include myoclonus, seizures, cerebellar ataxia, myopathy,[3] and ragged red fibers (RRF) on muscle biopsy, leading to the disease's name.

Secondary features include dementia, optic atrophy, bilateral deafness, peripheral neuropathy, spasticity, or multiple lipomata.

[3] Secondary features can include dementia, optic atrophy, bilateral deafness, peripheral neuropathy, spasticity, multiple lipomata, and/or cardiomyopathy with Wolff Parkinson-White syndrome.

As muscles are stained with Gömöri trichrome, characteristic ragged red fibers are visible under the microscope.

The mitochondrial aggregates cause the contour of the muscle fiber to become irregular, leading to the "ragged" appearance.

[14] If the individual has been experiencing myoclonus, the doctor will run a series of genetic studies to determine if it is a mitochondrial disorder.

[citation needed] The molecular genetic studies are run to identify the reason of for the mutations underlying the mitochondrial dysfunction.

They can go through computed tomography (CT) or magnetic resonance imaging (MRI).The classification for the severity of MERRF syndrome is difficult to distinguish since most individuals will exhibit multi-symptoms.

Multiple lipomas in the skin, sideroblastic anemia and pancytopenia in the metabolic system, or short stature might all be examples of patients with possible symptoms of MERRF disease.

High doses of coenzyme Q10, B complex vitamins, and L-Carnitine are used for the altered metabolic processing that results in the disease.

[citation needed] The Journal of Child Neurology published a paper in 2011 that discusses possible new methods to test for MERRF and other mitochondrial diseases through a simple swabbing technique.

Since the current understanding of the precise molecular mechanisms of these mutations is limited, there is no efficient method to treat their associated mitochondrial diseases.

All pathogenic mutants displayed pleiotropic phenotypes, with the exception of the G34A anticodon mutation, which solely affected aminoacylation.