ABSTRACT
Mapping the genome began soon after it was recognised that genes were physically located on the chromosomes, with co-located ‘linked’ genes found for Drosophila in America in 1913 and for the mouse in Britain shortly afterwards. The first human gene linkage was found in 1937 between colour blindness and haemophilia on the X chromosome by Bell and Haldane, and from 1951 an increasing number of other gene linkages were discovered using blood groups and other inherited protein variations as markers. Between 1973 and 1991 a series of international human gene mapping workshops were held which saw a detailed map of disease genes and genetic markers established on all chromosomes, boosted by the discovery of abundant inherited variation in DNA itself. From 1985 the Human Genome Project, with Britain playing a major role, was able to sequence increasing stretches of the human genome, being essentially completed in 2003. This has led to the new and still-fluid field of ‘genomics’, with sequencing techniques applied to numerous research projects and increasingly to genetic services, particularly for single gene disorders, though its efficacy for most common diseases and for wider medicine has still to be fully established.
