Why We Inherit Diseases From Our Family #75

• What are inherited disorders?

  Conditions passed on through certain alleles
• What is polydactyly?

  • Condition with extra fingers or toes
  • Usually does not cause other problems
  • Caused by a dominant allele
• What happens if one allele is the polydactyly allele?

  You still have the disorder
• What is the genetic diagram outcome when crossing a heterozygous individual with a homozygous normal individual for polydactyly?

  • Gametes: 1 dominant polydactyly, 3 normal
  • Offspring: 2 heterozygous (polydactyly), 2 homozygous normal
  • Phenotype ratio: 1:1 (50% chance for polydactyly)
• How is cystic fibrosis inherited?

  • Caused by a recessive allele
  • Requires two recessive alleles to have the condition
  • Most people are homozygous dominant
  • 1 in 25 are heterozygous carriers
• What does the lowercase f represent in cystic fibrosis?

  The recessive allele causing cystic fibrosis
• What is the phenotype ratio of offspring from two heterozygous carriers of cystic fibrosis?

  3 normal phenotypes to 1 cystic fibrosis
• What are the implications of being a carrier for cystic fibrosis?

  • Carriers have one copy of the allele
  • They do not have the condition
  • Can pass the allele to their children
• What is embryo screening?

  • Process of checking embryo genes
  • Identifies genetic disorders like polydactyly or cystic fibrosis
  • Allows parents to make informed decisions
• What might parents decide if a genetic disorder is found during embryo screening?

  To discard the embryo and use another
• What are the advantages of embryonic screening?

  • Reduces overall suffering from health problems
  • Saves money on treating genetic disorders
• What are the concerns regarding embryonic screening?

  • Implies genetic problems are less desirable
  • Could increase prejudice against affected individuals
  • Potential future screening for non-health traits
• What is the current legal status of screening for non-health traits in the UK?

  There are laws preventing this practice