inherited disorders & embryonic screening

• What are inherited disorders?

  Conditions passed on through certain alleles
• What is polydactyly?

  Condition with extra fingers or toes
• How is polydactyly inherited?

  It is caused by a dominant allele
• If one allele is polydactyly, what is the outcome?

  The individual will have polydactyly
• What is the genotype of a heterozygous individual with polydactyly?

  One dominant and one normal allele
• What is the offspring ratio when crossing a heterozygous polydactyly individual with a homozygous normal individual?

  • 2 heterozygous (polydactyly)
  • 2 homozygous normal
  • Ratio: 1:1 (50% chance)
• What causes cystic fibrosis?

  It is caused by a recessive allele
• What is the effect of cystic fibrosis on the body?

  It results in thick sticky mucus
• How many recessive alleles are needed for cystic fibrosis?

  Two recessive alleles are needed
• What is the genotype of most people regarding cystic fibrosis?

  Most are homozygous dominant
• What do we call individuals who carry one cystic fibrosis allele?

  They are called carriers
• What is the offspring ratio when crossing two carriers of cystic fibrosis?

  • 1 homozygous dominant
  • 2 heterozygous (carriers)
  • 1 homozygous recessive (cystic fibrosis)
  • Ratio: 3:1 (normal to cystic fibrosis)
• What is embryo screening?

  Checking embryos for genetic disorders
• What happens if a genetic disorder is found during embryo screening?

  The embryo may be discarded
• What are the advantages of embryonic screening?

  • Reduces overall suffering
  • Saves money on treatments
• What are the concerns regarding embryonic screening?

  • Implies genetic problems are undesirable
  • Potential for screening non-health traits
• What laws exist in the UK regarding genetic screening?

  There are laws to prevent misuse