Table 1.

Clinical Syndromes of Mitochondrial Diseases

DisorderPrimary FeaturesAdditional Features
Alpers-Huttenlocher syndrome
  • Hypotonia
  • Seizures
  • Liver failure
  • Renal tubulopathy
Ataxia neuropathy syndromes (ANS): Including MIRAS, SCAE, SANDO, MEMSA
  • SANDO
  • Other ANS: Sensory axonal neuropathy w/variable sensory & cerebellar ataxia
  • Epilepsy
  • Dysarthria, and/or
  • Myopathy
CPEO
  • External ophthalmoplegia
  • Bilateral ptosis
  • Mild proximal myopathy
KSS
  • PEO onset at age <20 years
  • Pigmentary retinopathy
  • One of the following: CSF protein >1g/L, cerebellar ataxia, heart block
  • Bilateral deafness
  • Myopathy
  • Dysphagia
  • Diabetes mellitus
  • Hypoparathyroidism
  • Dementia
Pearson syndrome
  • Sideroblastic anemia of childhood
  • Pancytopenia
  • Exocrine pancreatic failure
  • Renal tubular defects
Infantile myopathy and lactic acidosis (fatal & non-fatal forms)
  • Hypotonia in 1st year of life
  • Feeding & respiratory difficulties
  • Fatal form may be associated with a cardiomyopathy and/or the Toni-Fanconi-Debre syndrome
Leigh syndrome
  • Subacute relapsing encephalopathy
  • Cerebellar and brain stem signs
  • Infantile onset
  • Basal ganglia lucencies
  • Maternal history of neurologic disease or Leigh syndrome
NARP
  • Late-childhood or adult-onset peripheral neuropathy
  • Ataxia
  • Pigmentary retinopathy
  • Basal ganglia lucencies
  • Abnormal electroretinogram
  • Sensorimotor neuropathy
MELAS
  • Stroke-like episodes at age <40 years
  • Seizures and/or dementia
  • Ragged-red fibers and/or lactic acidosis
  • Diabetes mellitus
  • Cardiomyopathy (initially hypertrophic; later dilated)
  • Bilateral deafness
  • Pigmentary retinopathy
  • Cerebellar ataxia
MEMSA 1
  • Myopathy
  • Seizures
  • Cerebellar ataxia
  • Dementia
  • Peripheral neuropathy
  • Spasticity
MERRF
  • Myoclonus
  • Seizures
  • Cerebellar ataxia
  • Myopathy
  • Dementia
  • Optic atrophy
  • Bilateral deafness
  • Peripheral neuropathy
  • Spasticity
  • Multiple lipomata
LHON
  • Subacute painless bilateral visual failure
  • Males:females ~4:1
  • Median age of onset 24 years
  • Dystonia
  • Cardiac pre-excitation syndromes

CPEO = chronic progressive external ophthalmoplegia

KSS = Kearns-Sayre syndrome

LHON = Leber hereditary optic neuropathy

MELAS = mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes

MEMSA = myoclonic epilepsy myopathy sensory ataxia

MERRF = myoclonic epilepsy with ragged-red fibers

MIRAS = mitochondrial recessive ataxia syndrome

NARP = neurogenic weakness with ataxia and retinitis pigmentosa

SANDO = sensory ataxia neuropathy, dysarthria, ophthalmoplegia

SCAE = spinocerebellar ataxia with epilepsy

1.

Also referred to as MIRAS and SCAE

From: Mitochondrial Disorders Overview

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Pagon RA, Adam MP, Ardinger HH, et al., editors.
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