Genetic Variants

• Huntingtons Disease is caused by a dominant gene
• Cystic fibrosis is caused by a recessive gene
• What is cystic fibrosis?

  CF is a common inherited disease that affects the respiratory and digestive systems by producing abnormally thick mucus.
• To inherit cystic fibrosis, both alleles must be the SAME to develop this disease.
• Symptoms of cystic fibrosis

  • Coughs
  • Difficulty breathing
  • Repeated chest infections - bacteria is trapped and thrives in the mucus
  • Mucus also clogs ducts and blocks enzymes - resulting in poor digestion - low weight gain and energy levels
• What causes genetic variants?

  Mutations - changes in the sequence of bases in the DNA
• What are the 3 types of mutation?

  1. Point mutation
  2. Insertion mutation
  3. Deletion mutation
• What is point mutation?

  A change in a single nucleotide base in DNA.
• Why does point mutation cause no change to the amino acid?

  Because several triplets code for one amino acid
• In point mutation, even if the amino acid is changed, there may be no change to the structure or function of the protein produced.
• Why are insertion and deletion mutations more severe

  Because they cause changes to the way bases are divided into triplets.
• Insertion and deletion mutation changes every triplet from the mutation to the stop code and can cause changes to many amino acids.
• Insertion and deletion mutation are likely to seriously affect the shape and function of the protein.
• What is Huntington’s disease?

  Neurodegenerative disease.
• What does Huntingtons Disease affect?

  The brain