Gene therapy (Multiple Choice)

Gene therapy
  a. has never been used successfully with mammals.
  b. is a surgical technique that separates chromosomes that have failed to segregate properly
  during meiosis II.
  c. has been used successfully to treat victims of Huntington's disorder by removing the
  dominant damaging autosomal allele and replacing it with a harmless one.
  d. offers the possibility of replacing defective alleles with normal ones.
  e. may be used to clone individuals.

Question 2

More than 60 disorders have been mapped to chromosome
  a. 14.
  b. 21.
  c. 18.
  d. 12.
  e. 5.