monogenic diseases

• What is monogenic inheritance?

  Determination of a characteristic by a single gene
• What are mitochondria?

  Cellular organelles with an independent genome
• Why do mitochondria have folds called cristae?

  To increase surface area for oxidative phosphorylation
• What is the primary function of mitochondria?

  Generate energy in the form of ATP
• What role does cytochrome c play in apoptosis?

  Initiates a pathway of procaspase activation
• What is the endosymbiont hypothesis?

  One bacterium engulfed another, leading to a symbiotic relationship
• What does the endosymbiotic theory explain?

  Origin of mitochondria and chloroplasts from symbiotic bacteria
• Where is the mitochondrial genome located?

  Mitochondrial matrix
• How many genes does the mitochondrial genome encode?

  37 genes
• Why is the mitochondrial genome more prone to mutations?

  Less robust repair system and more reactive molecules
• What is heteroplasmy?

  Presence of different versions of mtDNA in an individual
• How does the severity of mitochondrial syndromes vary?

  Depends on the number of deactivated mitochondria in the egg
• What is Leber hereditary optic neuropathy?

  Sudden loss of vision due to mtDNA mutations
• What is mitochondrial replacement therapy?

  Transplanting nuclear DNA into a donor egg with healthy mtDNA
• What are lysosomes?

  Membrane-bound organelles containing hydrolytic enzymes
• What happens in lysosomal storage diseases (LSDs)?

  Substrates accumulate inside lysosomes, causing toxicity
• What is Gaucher's disease?

  Lysosomal storage disease due to lack of glucocerebrosidase
• What is the mechanism of Tay-Sachs disease?

  Lack of GM2 hexosaminidase A leading to GM2 accumulation

  
• What is Niemann-Pick disease Type A?

  Severe lysosomal storage disease due to lack of sphingomyelinase
• What is anticipation in nucleotide repeat expansion disorders?

  Progressively earlier or more severe disease expression in recent generations
• What is myotonic dystrophy?

  Muscular dystrophy due to unstable repeat expansions
• What are the clinical features of Huntington's disease?

  Loss of mental and physical control, chorea
• What are the key features of mitochondrial genetics?

  • Maternal inheritance
  • High mutation rate
  • Less robust DNA repair system
  • Heteroplasmy
• What are the main characteristics of lysosomal storage diseases?

  • Rare and hereditary
  • Autosomal recessive or X-linked
  • Accumulation of substrates in lysosomes
  • Affects metabolic reactions
• What are the three classes of diseases due to unstable repeat expansions?

  1. Noncoding repeats causing loss of protein expression
  2. Noncoding repeats conferring novel RNA properties
  3. Codon repeats conferring novel protein properties
• What are the clinical features of myotonic dystrophy?

  • Myotonia (inability to relax muscles)
  • Muscle weakness and wasting
  • Cardiac conduction defects
  • Testicular atrophy
  • Insulin resistance
  • Cataracts
• What are the key features of Huntington's disease?

  • Inherited, degenerative brain disorder
  • Loss of mental and physical control
  • Chorea (dance-like movements)
  • Caused by CAG repeat expansion in HD gene