MELAS Syndrome

Clinical Characteristics
Ocular Features: 

This progressive mitochondrial disorder primarily affects muscles and the CNS, including the visual system.  The pattern of ocular deficits is not consistent and those that are present are not specific, requiring the clinician to take the entire neurological picture into consideration.  Hemianopsia, cortical blindness and ophthalmoplegia may be present.  The ERG can show reduced b-wave amplitudes and VEPs may be absent.  The optic nerve head has been described as normal without the atrophy often seen with other mitochondrial disorders.  A pigmentary retinopathy may be present.

Systemic Features: 

The clinical picture is highly variable.  Most commonly patients have myopathy, encephalopathy, lactic acidosis, and stroke-like episodes.  The onset of symptoms is usually in the first two decades of life, most commonly consisting of headaches of sudden onset accompanied by vomiting and seizures.  The headaches may simulate migraines.  Weakness, lethargy, and apathy may be present early.  However, infants and young children may present with failure to thrive, developmental delay, and learning disabilities.  Neurosensory deafness is often seen and peripheral neuropathy is usually evident.  MRIs may show cerebellar hypoplasia and infarctions in the cerebral hemispheres.  Some patients have calcifications in the basal ganglia.  Patients may develop lactic acidosis.  Muscle biopsies often show ragged, red fibers.  The heart is commonly involved with both structural and rhythm defects.  Depending upon the degree and location of brain damage, patients may have hemiparesis, lethargy, ataxia, myoclonic jerks, cognitive decline, and dementia.  Morbidity and mortality are high.


MELAS syndrome is a group of disorders caused by mutations in mitochondrial genes (at least 9 have been identified) that alter transfer RNA molecules resulting in disruption of intramitochondrial synthesis of proteins involved in oxidative phosphorylation pathways.  It is both clinically and genetically heterogeneous.  One can expect that any familial occurrence would result from maternal transmission but the occurrence of heteroplasmy results in considerable variability in the severity of clinical disease.

Treatment Options: 

There is no effective treatment that prevents development of disease or that slows its progress.

Article Title: 


Latkany P, Ciulla TA, Cacchillo PF, Malkoff MD. Mitochondrial maculopathy: geographic atrophy of the macula in the MELAS associated A to G 3243 mitochondrial DNA point mutation. Am J Ophthalmol. 1999 Jul;128(1):112-4

PubMedID: 10482110

Goto Y, Horai S, Matsuoka T, Koga Y, Nihei K, Kobayashi M, Nonaka I. Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS): a correlative study of the clinical features and mitochondrial DNA mutation. Neurology. 1992 Mar;42(3 Pt 1):545-50

PubMedID: 1549215