Condition Lookup
Sub-Category:
Mitochondrial Disorders
Number of Conditions: 4
Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (MELAS)
Specialty: Genetics
Category: Single-Gene Disorders (Mendelian Inheritance)
Sub-category: Mitochondrial Disorders
Symptoms:
muscle weakness; recurrent headaches; vomiting; seizures; stroke-like episodes before age 40; hearing loss; diabetes mellitus; vision loss; cognitive decline
Root Cause:
Mutations in mitochondrial DNA (mtDNA) impair energy production in cells by affecting oxidative phosphorylation.
How it's Diagnosed: videos
Clinical assessment, brain MRI showing stroke-like lesions, muscle biopsy with ragged red fibers, and genetic testing for mtDNA mutations.
Treatment:
Symptomatic management with physical therapy, occupational therapy, and dietary supplementation (e.g., L-arginine, coenzyme Q10). Stroke prevention strategies may include arginine supplementation during acute episodes.
Medications:
No specific FDA-approved medications for MELAS; however, supplements like L-arginine and coenzyme Q10 (antioxidants and mitochondrial support therapies) are often recommended. Anticonvulsants may be prescribed for seizures (e.g., levetiracetam , a broad-spectrum anticonvulsant).
Prevalence:
How common the health condition is within a specific population.
Rare, with an estimated prevalence of 1 in 10,000 to 1 in 20,000 individuals worldwide.
Risk Factors:
Factors or behaviors that increase the likelihood of developing the condition.
Family history of mitochondrial disorders, maternally inherited mtDNA mutations.
Prognosis:
The expected outcome or course of the condition over time.
Progressive disorder with varying severity; life expectancy depends on the severity of symptoms and complications.
Complications:
Additional problems or conditions that may arise as a result of the original condition.
Stroke-like episodes, seizures, hearing loss, progressive neurological decline, diabetes mellitus, and cardiomyopathy.
Leber Hereditary Optic Neuropathy (LHON)
Specialty: Genetics
Category: Single-Gene Disorders (Mendelian Inheritance)
Sub-category: Mitochondrial Disorders
Symptoms:
painless, acute or subacute central vision loss; blurring or clouding of vision; progressive bilateral visual impairment
Root Cause:
Mutations in mtDNA cause defective oxidative phosphorylation, leading to the degeneration of retinal ganglion cells and optic nerve.
How it's Diagnosed: videos
Clinical ophthalmologic examination, optical coherence tomography (OCT), and genetic testing for mtDNA mutations (e.g., m.11778G>A).
Treatment:
Vision aids for low vision; idebenone, an antioxidant, is used to improve outcomes in some cases.
Medications:
Idebenone (antioxidant therapy) is often prescribed; it is classified as a free radical scavenger and mitochondrial support agent.
Prevalence:
How common the health condition is within a specific population.
Estimated at 1 in 50,000 individuals, with higher prevalence in males than females.
Risk Factors:
Factors or behaviors that increase the likelihood of developing the condition.
Family history of LHON, tobacco use, alcohol abuse, and exposure to environmental toxins may trigger symptoms in carriers.
Prognosis:
The expected outcome or course of the condition over time.
Variable; some patients experience partial recovery of vision, but many remain severely visually impaired.
Complications:
Additional problems or conditions that may arise as a result of the original condition.
Permanent vision loss, depression due to visual disability, and potential progression to bilateral blindness.
Myoclonic Epilepsy with Ragged-Red Fibers (MERRF)
Specialty: Genetics
Category: Single-Gene Disorders (Mendelian Inheritance)
Sub-category: Mitochondrial Disorders
Symptoms:
myoclonus (involuntary muscle jerks); epilepsy; ataxia; muscle weakness; hearing loss; short stature; exercise intolerance; cognitive impairment
Root Cause:
Mutations in mtDNA impair mitochondrial function, affecting energy production in muscle and nerve tissues.
How it's Diagnosed: videos
Clinical features, muscle biopsy showing ragged red fibers, and genetic testing for mtDNA mutations (e.g., m.8344A>G).
Treatment:
Symptomatic treatment including antiepileptic drugs for seizures, physical therapy, and dietary supplementation (e.g., L-carnitine, coenzyme Q10).
Medications:
Anticonvulsants like valproate or levetiracetam are used for seizure control; L-carnitine and coenzyme Q10 are used as mitochondrial support therapies.
Prevalence:
How common the health condition is within a specific population.
Rare, with an estimated prevalence of 1 in 400,000 individuals.
Risk Factors:
Factors or behaviors that increase the likelihood of developing the condition.
Family history of mitochondrial disorders and maternally inherited mtDNA mutations.
Prognosis:
The expected outcome or course of the condition over time.
Progressive disease with variability in severity; life expectancy is reduced in severe cases.
Complications:
Additional problems or conditions that may arise as a result of the original condition.
Refractory epilepsy, progressive neurological decline, cardiomyopathy, and respiratory failure.
Kearns-Sayre Syndrome (KSS)
Specialty: Genetics
Category: Single-Gene Disorders (Mendelian Inheritance)
Sub-category: Mitochondrial Disorders
Symptoms:
progressive external ophthalmoplegia (weakness of eye muscles); ptosis (drooping eyelids); retinal degeneration; cardiac conduction defects; ataxia; hearing loss; short stature; diabetes mellitus
Root Cause:
Large-scale deletions of mtDNA disrupt mitochondrial energy production, affecting multiple organ systems.
How it's Diagnosed: videos
Clinical features, muscle biopsy showing ragged red fibers, and genetic testing for mtDNA deletions.
Treatment:
Supportive treatment including cardiac pacing for conduction defects, hearing aids, physical therapy, and dietary supplementation (e.g., coenzyme Q10).
Medications:
No specific FDA-approved treatments; coenzyme Q10 and antioxidants like vitamin E are commonly recommended for mitochondrial support.
Prevalence:
How common the health condition is within a specific population.
Rare, affecting approximately 1 in 100,000 individuals.
Risk Factors:
Factors or behaviors that increase the likelihood of developing the condition.
Sporadic occurrence, though some familial cases with mtDNA deletions have been reported.
Prognosis:
The expected outcome or course of the condition over time.
Progressive disease; life expectancy depends on the severity of cardiac and neurological complications.
Complications:
Additional problems or conditions that may arise as a result of the original condition.
Complete heart block, progressive vision loss, hearing impairment, and endocrinopathies like diabetes mellitus.