LHON: Leber’s Hereditary Optic Neuropathy

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Usually manifests itself in the second or third decade of life

A sudden loss of vision due to optic nerve neuropathy

There seldom are additional neurological signs

Maternal inheritance – in 90% of the patients there is a mutation in one of the mitochondrial DNA genes: MT-ND1, MT-ND4, MT-ND6

Higher incidence in males, for an unknown reason

 

NARP: Neuropathy, Ataxia and Retinitis Pigmentosa

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Neuropathy

Ataxia

Degeneration of the retina

Sometimes delayed development

Maternal inheritance

Specific mutation on the mitochondrial gene for ATPase

 

MELAS: Mitochondrial Encephalopathy, Lactic Acidosis and Stroke-like Episodes

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Normal early development

Developmental regression in childhood or the beginning of adolescence

Short stature, vomiting attacks, seizures, myopathy, migraines, lactic acidosis, loss of hearing, dementia, cortical blindness

In a muscle biopsy, a Gomori Trichrome stain will show fibers with an accumulation of mitochondria

Electron microscopy will show an increase in the quantity and size of mitochondria and a change in their shape

Maternal inheritance, caused by a mutation in the leucine tRNA

 

MERRF: Myoclonic Epilepsy with Ragged Red Muscle Fibers 

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Ataxia

Myoclonic seizures

Numbness

Dementia

In a muscle biopsy, a Gomori Trichrome RRF stain will show fibers with an accumulation of mitochondria

Maternal inheritance, caused by a mutation in the leucine tRNA

 

MIMyCa: Maternally Inherited Myopathy and Cardiomyopathy

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Sometimes manifests itself already in early childhood, and sometimes later

Hypertrophic cardiomyopathy usually, and which later becomes dilated

Muscle weakness – myopathy

Maternal inheritance

 

Maternally Inherited Diabetes Mellitus and Deafness

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Neural deafness

Diabetes

Maternal inheritance

 

Kearns-Sayre Syndrome

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Manifests itself before age 20 years

Muscle biopsy shows RRF

Eye muscle palsy

Diabetes

Deafness

Short stature

Muscle weakness

Cardiac conduction block

Kidney tubular function disorder

Lactic acidosis

Changes in the brain’s white matter and basal ganglia calcification

The disease is not inherited and is due to a large deletion of the mitochondrial DNA

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Pearson’s Syndrome

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Its onset is in the first year of life

Severe disorder of the bone marrow: sideroblastic anemia, leukopenia, thrombocytopenia

Pancreatic disorders, loss of lipids

Failure to thrive

Hepatic disorder

The disease is not inherited and is due to a large deletion of the mitochondrial DNA

High mortality in infancy

Sometimes spontaneous remission occurs, and later symptoms of Kearns-Sayre Syndrome develop

 

Leigh Disease

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Onset in infancy

Developmental delay

Inability to grow

Eating problems

Ataxia

Seizures

Hypotonia

Cardiomyopathy

Breathing problems due to loss of the brainstem function which is usually the cause of death

Loss of vision

Lesions in the basal ganglia and brainstem

Different inheritance patterns

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For more information please visit the United Mitochondrial Disease Foundation site UMDF