The Human Genome Project

  1: What is the public project for sequencing the human genome?
  2: Has the human genome been completely sequenced?
  3: How many genes do humans have?
  4: Why is it so difficult to find the genes in a human genome sequence?
  5: Where did the sequenced human DNA come from?
  6: Is the human genome “freely available”? If not, who owns it?
  7: Why was there a Human Genome Project What is its use?
  8: Who were the members of the international consortium What was the role of each of them?
  9: What was the French contribution to the Human Genome Project?
  10: How much did the Human Genome Project cost?
  11: With the end of the Human Genome Project, are the large sequencing centers still useful?

  The DNA sequences produced by the Human Genome Project did not come from a single donor, but from several anonymous donors recruited in the United States. The procedure adopted guaranteed that the identity of the volunteers would not be revealed. Recruitment was carried out by posting announcements in the area around two laboratories where the DNA “libraries” were being prepared. The donors, which were of diverse origins, were told about the project and gave their informed consent. Their DNA was extracted from blood cells collected by venepuncture. Many precautions were taken to avoid the possibility of revealing the identity of the donor of the sample. Furthermore, five to ten samples were prepared for each sample utilized, such that no donor could be sure that his/her DNA was part of the material sequenced. (Click on this link for supplementary information)

Even starting with a single donor, a single version of the sequence would not be obtained. This is because each human being has one set of chromosomes from his mother and the other from his father and the sequence of the paternal chromosome differs from the sequence of the homologous chromosome from the mother at certain positions. Under the hypothesis of a single donor, the large DNA fragments selected by the scientists to construct a “map” of the chromosome could come from one or the other of the two homologous chromosomes. The sequence of each large fragment would be homogeneous, of paternal or maternal origin, but differences would appear in the regions where the two large fragments from paternal and maternal chromosomes overlap. Since the sequence of each large fragment is established with a high level of confidence, these divergences can be distinguished from sequencing errors and classified as polymorphisms. This is an advantage of the “clone-by-clone” strategy followed by the consortium. Beginning with several donors, the sequence of large fragments may have come not only from two homologous chromosomes from the same individual, but also from different individuals, and in this way more polymorphisms can be discovered.