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All humans have unique gene sequences, therefore the data published by the HGP does not represent the exact sequence of each and every individual's genome. It is the combined genome of a small number of anonymous donors. The HGP genome is a scaffold for future work in identifying differences between individuals. Most of the current effort in identifying differences between individuals involves single nucleotide polymorphisms and the HapMap.
Whose genome was sequenced?[edit | edit source]
This answer is posted as supplied by Dr. Marvin Stodolsky, U.S. DOE Office of Biological and Environmental Research, Office of Science. This statement is believed to be in the public domain since it is a work of the United States government
Whose genome was sequenced in the public (HGP) and private projects?
The human genome reference sequences do not represent any one person’s genome. Rather, they serve as a starting point for broad comparisons across humanity. The knowledge obtained is applicable to everyone because all humans share the same basic set of genes and genomic regulatory regions that control the development and maintenance of their biological structures and processes.
In the international public-sector Human Genome Project (HGP), researchers collected blood (female) or sperm (male) samples from a large number of donors. Only a few of many collected samples were processed as DNA resources. Thus the donor identities were protected so neither donors nor scientists could know whose DNA was sequenced. DNA clones from many different libraries were used in the overall project.
Technically, it is much easier to prepare DNA cleanly from sperm than from other cell types because of the much higher ratio of DNA to protein in sperm and the much smaller volume in which purifications can be done. Using sperm does provide all chromosomes for study, including equal numbers of sperm with the X (female) or Y (male) sex chromosomes. However, HGP scientists also used white cells from the blood of female donors so as to include female-originated samples.
In the Celera Genomics private-sector project, DNAs from a few different genomes were mixed up and processed for sequencing. The DNA resources used for these studies came from anonymous donors of European, African, American (North, Central, South), and Asian ancestry. The lead scientist of Celera Genomics at that time, Craig Venter, has since acknowledged that his DNA was one of those in the pool.
Many small regions of DNA that vary among individuals (called polymorphisms) also were identified during the HGP, mostly single nucleotide polymorphisms (SNPs). Most SNPs are without physiological effect, although a minority contribute to the delightful and beneficial diversity of humanity. A much smaller minority of polymorphisms affect an individual’s susceptibility to disease and response to medical treatments.
Although the HGP has been completed, SNP studies continue in the International HapMap Project, whose goal is to identify patterns of SNP groups (called haplotypes, or “haps”). The DNA samples for the HapMap came from a total of 270 individuals: Yoruba people in Ibadan, Nigeria; Japanese in Tokyo; Han Chinese in Beijing; and the French Centre d’Etude du Polymorphisme Humain (CEPH) resource.