The current human genome sequencing efforts are being carried out on DNA that has been obtained from cells of a number of different donors. Donors from the Celera project self-identified as different ethnic groups. From human sequences assembled to date, two unrelated people will on average have one different nucleotide per 1000 base pairs of their total DNA sequence, a percentage of difference of about 0.1%. These single nucleotide changes are called SNPs (Single Nucleotide Polymorphisms). Despite the presence of polymorphisms, the genome project should still be very useful, because the majority of the protein-encoding DNA information will be the same in all people.

As the genome reaches "completion," scientific explorations have already branched out into transcriptomics, proteomics, structural genomics, and comparative genomics.

Transcriptomics

involves large-scale analysis of messenger RNAs from active genes to follow when, where, and under what conditions genes are expressed.

Proteomics

the study of protein expression and function, can bring researchers closer to what's actually happening in the cell.

Structural genomics

generate the 3-D structures of one or more proteins, thus offering clues to function and biological targets for drug design.

Comparative genomics

analyzes DNA sequence patterns of humans and well-studied model organisms side-by-side-has become one of the most powerful strategies for identifying human genes and interpreting their function.

In order to do comparative genomics, the genomes of other organisms need to be available. See the list of model organisms at NCBI Genomic Biology page at http://www.ncbi.nih.gov/Genomes/. The National Advisory Council for Human Genome Research has recommended adding the cow and the dog to a growing group of high priority organisms (including chimpanzee, chicken and honeybee) that should be considered for genome sequencing as capacity becomes available. Read more about the decision process at http://www.genome.gov/page.cfm?pageID=10004650.