Table 1. [Clinical Syndromes of mtDNA Disorders]. - GeneReviews®

Disorder	Primary Features	Additional Features
CPEO	External ophthalmoplegia Bilateral ptosis	Mild proximal myopathy
KSS	PEO onset age <20 yrs Pigmentary retinopathy One of the following: CSF protein >1 g/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
Leigh syndrome	Subacute relapsing encephalopathy Cerebellar & 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 yrs Seizures &/or dementia Ragged-red fibers &/or lactic acidosis	Diabetes mellitus Cardiomyopathy (initially hypertrophic; later dilated) Bilateral deafness Pigmentary retinopathy Cerebellar ataxia
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 yrs	Dystonia Cardiac pre-excitation syndromes

Disorder

Primary Features

Additional Features

CPEO

External ophthalmoplegia
Bilateral ptosis

Mild proximal myopathy

KSS

PEO onset age <20 yrs
Pigmentary retinopathy
One of the following: CSF protein >1 g/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

Leigh syndrome

Subacute relapsing encephalopathy
Cerebellar & 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 yrs
Seizures &/or dementia
Ragged-red fibers &/or lactic acidosis

Diabetes mellitus
Cardiomyopathy (initially hypertrophic; later dilated)
Bilateral deafness
Pigmentary retinopathy
Cerebellar ataxia

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 yrs

Dystonia
Cardiac pre-excitation syndromes

From: Primary Mitochondrial Disorders Overview

GeneReviews^® [Internet].

Adam MP, Feldman J, Mirzaa GM, et al., editors.

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