MELAS and Parkinson's Disease Overview
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Questions and Answers

What does MELAS stand for?

  • Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like Episodes (correct)
  • Mitochondrial Encephalopathy, Lactic Acid, and Stroke
  • Muscle, Encephalopathy, Lactic Acid, Stroke
  • Metabolic Encephalopathy, Lactic Acidosis, and Systolic Episodes

MELAS primarily affects the respiratory system.

False (B)

At what age range is MELAS typically diagnosed?

2 to 15 years

MELAS is associated with a buildup of __________ in the body.

<p>lactic acid</p> Signup and view all the answers

Match the MELAS symptoms with their descriptions:

<p>Vomiting = A common gastrointestinal symptom Abdominal pain = Discomfort in the stomach area Extreme tiredness = Severe fatigue or lack of energy Lactic acidosis = Buildup of lactic acid in the body</p> Signup and view all the answers

What is the primary region of the brain involved in dopamine production that is affected in Parkinson's disease?

<p>Substantia nigra (A)</p> Signup and view all the answers

The striatum is not involved in the control of movement and motivation.

<p>False (B)</p> Signup and view all the answers

What is the immediate precursor of dopamine used in replacement therapy for Parkinson's disease?

<p>L-DOPA</p> Signup and view all the answers

In Parkinson's disease, there is a gradual loss of ________ producing neurons.

<p>dopamine</p> Signup and view all the answers

Match the following brain regions or terms with their corresponding functions related to Parkinson's disease:

<p>Substantia nigra = Production of dopamine Striatum = Control of movement and motivation L-DOPA = Dopamine replacement therapy Dopamine deficiency = Severity of motor syndrome</p> Signup and view all the answers

At what rate does LHON occur in the population?

<p>1:50,000 (C)</p> Signup and view all the answers

LHON most commonly appears in individuals over the age of 35.

<p>False (B)</p> Signup and view all the answers

What is the main pathology associated with LHON?

<p>optic nerve atrophy</p> Signup and view all the answers

Individuals with LHON experience a subacute loss of _____ vision.

<p>central</p> Signup and view all the answers

What supportive management strategies are recommended for individuals affected by LHON?

<p>Smoking cessation (B)</p> Signup and view all the answers

Match the therapy or management strategy with its description:

<p>Idebenone Therapy = Investigational medication to enhance cellular energy production Genetic Counseling = Helps families understand the genetic basis of the condition Low-vision aids = Tools to assist individuals in making the most of their residual vision Vision rehabilitation programs = Programs to support adapting to vision loss</p> Signup and view all the answers

All progeny of an affected female with LHON will manifest the disease.

<p>True (A)</p> Signup and view all the answers

What lifestyle changes should individuals with LHON consider to manage their condition?

<p>Avoid smoking and excessive alcohol consumption</p> Signup and view all the answers

What is the primary purpose of mitochondrial replacement therapy?

<p>To avoid passing defective mitochondria to children (A)</p> Signup and view all the answers

Alzheimer's disease is the least common form of adult-onset dementia.

<p>False (B)</p> Signup and view all the answers

What percentage chance does an 80-year-old person have of developing Alzheimer's disease?

<p>30%</p> Signup and view all the answers

Amyloid plaques are primarily made up of _____ protein.

<p>beta-amyloid</p> Signup and view all the answers

Match the following terms with their descriptions:

<p>Amyloid Plaques = Abnormal protein deposits disrupting neuronal function Neurofibrillary Tangles = Accumulations of tau protein impairing neuronal transport Mitochondrial Dysfunction = Effects of aging and lifestyle on mitochondrial health Alzheimer's Disease = Most common form of adult-onset dementia</p> Signup and view all the answers

Which factors can lead to mitochondrial dysfunction?

<p>Age, genetics, lifestyle, and environment (B)</p> Signup and view all the answers

What is a consequence of mitochondrial dysfunction in cells?

<p>Decreased Respiration (B)</p> Signup and view all the answers

Amyloid-beta (Aβ) peptides accumulation is linked to neuroinflammation.

<p>True (A)</p> Signup and view all the answers

Neurofibrillary tangles are found outside nerve cells.

<p>False (B)</p> Signup and view all the answers

Why don't paternal mitochondria get passed to children?

<p>They are degraded.</p> Signup and view all the answers

Name a type of medication used to manage Alzheimer's Disease symptoms.

<p>AChE inhibitors</p> Signup and view all the answers

Parkinson's Disease typically has an onset age of _____ years.

<p>60</p> Signup and view all the answers

Which of the following is an NMDA antagonist used in Alzheimer's Disease management?

<p>Namenda® (A)</p> Signup and view all the answers

Match the following conditions with their characteristics:

<p>Alzheimer's Disease = Accumulation of amyloid-beta (Aβ) and cognitive decline Parkinson's Disease = Resting tremor and rigidity</p> Signup and view all the answers

Cholinesterase inhibitors work by blocking the NMDA receptor for glutamate.

<p>False (B)</p> Signup and view all the answers

What percentage of people aged 80 and older are affected by Parkinson's Disease?

<p>10%</p> Signup and view all the answers

What role does rotenone play in relation to Parkinson's disease?

<p>It is used to induce animals to become study models. (C)</p> Signup and view all the answers

Statins inhibit the biosynthesis of CoQ10.

<p>True (A)</p> Signup and view all the answers

What type of mutations in mitochondrial DNA could lead to reduced ATP synthesis?

<p>Transition mutations or transversion mutations</p> Signup and view all the answers

Larger animals typically have slower metabolic rates, often leading to longer lifespans, while birds have both _____ metabolic rates and extended lifespans.

<p>fast</p> Signup and view all the answers

Match the drugs to their effects:

<p>Statins = Inhibit CoQ10 biosynthesis Anti-retroviral drugs = Inhibit mitochondrial DNA polymerase Rotenone = Induce study models for Parkinson's Transition mutations = Compromise ATP synthesis</p> Signup and view all the answers

What is a noted benefit of the efficiency of bird mitochondria?

<p>Fewer harmful free radicals (B)</p> Signup and view all the answers

Transition mutations occur when a purine is changed to a pyrimidine.

<p>True (A)</p> Signup and view all the answers

What do anti-retroviral drugs inhibit in relation to HIV treatments?

<p>Mitochondrial DNA polymerase</p> Signup and view all the answers

Flashcards

MELAS Symptoms

MELAS, a mitochondrial disorder, causes lactic acidosis (excess lactic acid), resulting in symptoms like vomiting, abdominal pain, and fatigue.

MELAS Cause

MELAS is mainly caused by mutations in mitochondrial DNA (mtDNA) or nuclear DNA, affecting the brain, nervous system, and muscles.

MELAS impact

MELAS primarily impacts brain function, neurons, and muscle tissues and often starts in childhood, usually diagnosed by age 20.

MELAS Diagnosis Age

MELAS diagnosis usually occurs between ages 2 and 15, but most cases are detected before age 20.

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Lactic Acidosis

Lactic acidosis is a condition where there's a buildup of lactic acid in the body, which can cause a range of symptoms.

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LHON Prevalence

Leber's hereditary optic neuropathy (LHON) affects about 1 in 50,000 people, typically appearing in young adulthood (15-35), but can occur at any age.

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LHON Vision Loss

LHON often causes painless, gradual loss of central vision in both eyes.

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LHON Inheritance

LHON is maternally inherited; affected mothers transmit the disease to all their children, but affected fathers do not.

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LHON Optic Nerve Atrophy

A key feature of LHON is the development of optic nerve damage, causing vision loss.

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LHON Management

While LHON has no cure, supportive care such as eyewear, vision aids, and rehabilitation helps affected individuals.

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LHON Lifestyle

Avoiding smoking and excessive alcohol is advised in LHON to minimize oxidative stress on the mitochondria.

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Idebenone Therapy

Idebenone is an experimental medication that may improve cellular energy production to potentially slow LHON progression.

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Genetic Counseling

Genetic counseling advises families on the condition's genetic basis, and helps them and affected individuals make informed decisions.

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Substantia Nigra

A brain region critical for producing dopamine, a neurotransmitter essential for smooth movement and motivation.

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Dopamine Deficiency in Parkinson's

Parkinson's disease is caused by a gradual loss of dopamine-producing neurons in the substantia nigra, leading to a decrease in dopamine in the striatum.

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The Striatum

A deep brain region involved in selecting actions, controlling movement, and motivation. It relies on dopamine for these functions.

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L-DOPA

A precursor to dopamine, used to treat Parkinson's disease by increasing dopamine levels in the brain.

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Parkinson's Disease Pathology

Parkinson's disease involves the degeneration of dopamine-producing neurons in the substantia nigra, leading to a reduction in dopamine levels in the striatum, disrupting movement control.

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Mitochondrial Replacement Therapy

A modified IVF method allowing women with mitochondrial disorders to avoid passing defective mitochondria to their children.

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Mitochondrial Disorders

Genetic conditions affecting mitochondria, potentially passed to offspring.

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Amyloid Plaques

Abnormal protein deposits in the brain, disrupting nerve cell function in Alzheimer's disease.

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Neurofibrillary Tangles

Abnormal accumulations of tau protein within nerve cells, impairing function in Alzheimer's.

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Alzheimer's Disease

Most common form of adult-onset dementia, characterized by amyloid plaques and neurofibrillary tangles.

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Mitochondrial Dysfunction

Impaired functioning of mitochondria, potentially attributed to factors like age, genetics, lifestyle, and environment.

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Risk Factor for Alzheimer's Disease

Aging is a key risk factor for the development of Alzheimer's.

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IVF

In-vitro fertilization, a process that can be used to help people get pregnant.

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Oxidative Stress

An imbalance in the production and neutralisation of free radicals, causing damage to cells, including mtDNA

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mtDNA Damage

Damage to mitochondrial DNA (mtDNA) caused by free radicals, further impairing mitochondrial function.

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Alzheimer's Disease (AD) risk factors

A neurodegenerative disease associated with abnormal protein accumulation, neuroinflammation and eventual neurodegeneration. Mitochondrial dysfunction is a contributing factor.

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Amyloid-beta (Aβ) peptides

Abnormal protein deposits, a hallmark of Alzheimer's disease. They accumulate in the brain, leading to cell damage.

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Neuroinflammation

Inflammation in the nervous system, a contributing factor to neurodegeneration.

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Parkinson's Disease (PD)

A progressive neurodegenerative disorder affecting movement, with symptoms like tremors and rigidity.

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AChE Inhibitors (for AD)

Drugs that block the enzyme acetylcholinesterase, increasing acetylcholine levels and improving communication between brain cells.

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Mitochondrial Theory of Aging

The idea that aging is caused by the accumulation of damage to mitochondrial DNA (mtDNA), leading to reduced ATP production and impaired cellular function.

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Transition Mutations in mtDNA

A type of mutation in mtDNA where a purine base (adenine or guanine) is replaced by another purine base or a pyrimidine base (cytosine or thymine) is replaced by another pyrimidine.

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Transversion Mutations in mtDNA

A type of mutation in mtDNA where a purine base is replaced by a pyrimidine base, or vice versa.

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Impact of mtDNA Mutations on ATP Synthesis

Mutations in mtDNA, especially transition or transversion mutations, can disrupt the production of proteins involved in ATP synthesis, leading to reduced energy production.

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Mitochondrial Efficiency and Longevity

The efficiency of mitochondria in producing energy and minimizing harmful free radicals plays a crucial role in determining lifespan and susceptibility to age-related diseases.

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Birds' Longevity Paradox

Despite having fast metabolic rates, birds have longer lifespans and are less prone to age-related diseases compared to other animals with slower metabolic rates, which can be attributed to their highly efficient mitochondria.

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Tortoises and Longevity

Tortoises, known for their long lifespans, often have slower metabolic rates, which contributes to their extended lifespans.

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Study Notes

Unit 8: Mitochondrial Disorders

  • Mitochondrial disorders are primarily caused by mutations in mitochondrial DNA (mtDNA)
  • External factors, and oxidative stress can also contribute.
  • Mutations can disrupt the assembly of respiratory chain enzyme complexes and ATP synthase, impacting oxidative phosphorylation.
  • Mutations can also occur in nuclear DNA and affect mitochondrial functions.
  • Mitochondrial disorders can affect various organs and systems, leading to diverse clinical symptoms.

Dynamics of Mitochondrial Adaptation and Maintenance

  • Mitochondria undergo dynamic processes like biogenesis (creation of new mitochondria), fission (division into two), fusion (two mitochondria fusing into one), repair (fixing minor damage), and mitophagy (selective removal of damaged mitochondria).
  • These processes are crucial for adapting and maintaining cellular health.

Mitochondria and Reactive Oxygen Species (ROS)

  • ROS is a natural byproduct of the electron transport chain.
  • Excessive ROS can damage proteins, lipids, and DNA, leading to DNA mutations and genetic instability.
  • Mitochondrial oxidative damage can result in the release of cytochrome c into the cytosol, triggering apoptosis.

Mitochondrial Genome Maintenance

  • Damaged mtDNA can be repaired or degraded.
  • Severely damaged mtDNA may trigger mitophagy and apoptosis.

Mitochondrial Disorders: Types and Consequences

  • Mitochondrial disorders can affect multiple systems like the nervous, endocrine, gastrointestinal, musculoskeletal, and cardiovascular systems.
  • Mitochondrial disorders range widely in severity, from infancy to later life, and display diverse symptoms depending on the affected organ.

Primary vs. Secondary Mitochondrial Disorders

  • Primary Mitochondrial Disease (PMD): Directly caused by genetic mutations in either mtDNA or the nuclear DNA encoding for mitochondrial components, often inherited from one or both parents. These mutations specifically target the mitochondria.
  • Secondary Mitochondrial Dysfunction: Not directly due to mtDNA mutations but stems from other diseases or conditions (like genetic mutations affecting non-mitochondrial genes, environmental factors, or drugs) and environmental factors.

MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis, and Stroke-like episodes)

  • Primarily impacts the brain, nervous system (encephalo-), and muscles (myopathy).
  • Typically diagnosed in childhood, most commonly between ages 2-15.
  • Main characteristic is lactic acidosis (build-up of lactic acid).
  • Increased acidity in blood can lead to variety of symptoms including vomiting, abdominal pain, extreme tiredness, muscle weakness, loss of bowel control, and difficulty breathing.

LHON (Leber's Hereditary Optic Neuropathy)

  • A maternally inherited genetic disorder causing sudden vision loss due to optic nerve damage.
  • Typically develops in young adulthood (ages 15-35), but can occur at any age.
  • Characterized by bilateral, painless, subacute loss of central vision.

Mitochondrial Replacement Therapy

  • A modified in vitro fertilization technique to avoid passing on diseased mitochondria.
  • The technique involves transferring the nucleus from the mother's egg into an enucleated healthy egg from a donor.

Alzheimer's Disease (AD)

  • A progressive neurodegenerative disease causing dementia, characterized by amyloid plaques and neurofibrillary tangles.
  • Plaques are abnormal protein deposits primarily made up of beta-amyloid protein.
  • Tangles are abnormal accumulations of tau protein within nerve cells.
  • These disruptions impair neuronal transport and ultimately lead to neuronal death.
  • AD is linked to mitochondrial dysfunction, exacerbated by factors like aging and environmental influences.

Parkinson's Disease (PD)

  • A slowly progressive neurodegenerative disorder affecting movement.
  • Characterized by resting tremor, stiffness (rigidity), slow/decreased movement (bradykinesia), and gait/postural instability.
  • The mean age of onset is around 60 years.
  • Pathology of PD involves loss of dopamine-producing neurons in the substantia nigra, a critical brain region mediating movement.
  • Dopamine deficiency is the cause of motor dysfunction and is addressed with L-DOPA.

Drug-Induced Mitochondrial Damage

  • Some medications can harm mitochondria and trigger health problems.
  • Mitochondrial damage can lead to various side effects, some severe, like liver failure.

Mitochondrial Theory of Aging

  • Transition and transversion mutations in mitochondrial DNA (mtDNA) are factors related to decline in ATP synthesis.
  • Reduced ATP synthesis compromises essential functions in the aging process.

Mitochondria and Longevity

  • Larger animals typically have slower metabolic rates and longer lifespans, correlating with reduced mitochondrial oxidative stress.

Treatment and Management Strategies

  • There is no cure for many mitochondrial diseases, but treatments aim to manage symptoms and potentially slow disease progression.
  • Strategies for diverse disorders like MELAS and LHON may involve symptomatic management like dietary changes, medications (for seizures, e.g.), and supportive interventions to enhance the patient's quality of life.

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Mitochondrial Disorders - Unit 8 PDF

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Test your knowledge about MELAS and Parkinson's disease through this quiz. Explore their symptoms, diagnosis age, and associated characteristics. Analyze the brain functions involved in these conditions and the management strategies recommended for patients.

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