Human Genome Project

The Human Genome Project (HGP) was launched in 1990 and completed in 2003. At an estimated cost of 3 US dollars per base pair for about 3 × 10⁹ bp, the projected cost was about 9 billion US dollars.

Its goals included identifying all the approximately 20,000–25,000 human genes, finding the sequence of the 3 billion base pairs, storing the data in databases, improving analysis tools, transferring technology to industry and addressing ethical, legal and social issues (ELSI).

The National Institutes of Health and the U.S. Department of Energy coordinated it. The Wellcome Trust (U.K.) was a major partner, and Japan, France, Germany, China and others contributed further.

Two approaches were used: Expressed Sequence Tags (ESTs), which focus on genes expressed as RNA, and sequence annotation, which sequences the whole genome, coding and non-coding, and assigns functions later.

DNA was broken into fragments, cloned in hosts using BAC (bacterial artificial chromosome) and YAC (yeast artificial chromosome) vectors, and sequenced by automated sequencers based on Frederick Sanger's method. The sequence of chromosome 1 was completed last, in May 2006.

The human genome has about 3164.7 million bases. An average gene is 3000 bases long; the largest known gene, dystrophin, is 2.4 million bases.

The estimated total is about 30,000 genes, much lower than the 80,000 to 1,40,000 estimated earlier. Nearly 99.9 per cent of nucleotide bases are the same in all people, and over half of the discovered genes have unknown functions.

Proteins are coded by under 2 per cent of the genome, while repeated sequences make up a very large portion of it. The most genes (2968) are on chromosome 1 and the fewest (231) on Y. About 1.4 million single-base differences (SNPs, single nucleotide polymorphisms) were located.