Polydactyly

• Polydactyly II


  Inherited disorder where people have extra fingers or toes
• Polydactyly II


  • Caused by a dominant allele
  • A person with one copy of the polydactyly allele and one copy of the normal allele will have polydactyly
  • You cannot be a carrier of the polydactyly allele
• Cross between a man heterozygous for the polydactyly allele and a woman homozygous for the normal allele


  1. 50% of offspring are heterozygous for the polydactyly allele and have polydactyly

  2. 50% of offspring are unaffected by polydactyly
• The ratio of polydactyly to unaffected offspring is 1:1
• Probabilities mean it's possible all offspring could have polydactyly or all could be unaffected
• There are many inherited disorders in humans
• Embryo screening


  Embryos are tested to see if they have the alleles for inherited disorders, and embryos without the defective alleles are implanted
• Issues with embryo screening

  • It is expensive
  • A large number of embryos are created but only a small number are implanted, meaning healthy embryos are destroyed which some find unethical
  • In the future, embryos could be screened to produce offspring with desirable features like height or intelligence, which many find unethical
• Gene therapy


  Correcting faulty alleles to treat inherited disorders, but it is still experimental