A coordinated international project, begun in 1988, to map the entire human genome so that the genes could be isolated and sequenced (see dna sequencing). It involved the production of a DNA library. The full draft sequence was completed in 2000 and published in February 2001, and the high-quality finished sequence was completed in April 2003, two years ahead of schedule. Subsequent work has shown that the haploid human genome contains about 3.2×109 nucleotide base pairs, but only around 21 000 protein-coding genes. Alternative splicing in about 50% of these means that the number of protein products is actually much greater. Moreover, there are many more ‘RNA genes’, sequences encoding the various types of RNA used for implementation and control of gene expression.