GENETIC SELECTION > INFORMATION > SHEET 4

The human genome project

	Dr Burnside

DOCTOR BURNSIDE: Of course by the time your children are thinking of starting their families, all this won’t be necessary. Give it a few more years and we’ll all know what we’re made up of. The human genome, the last great unexplored continent, finally mapped out.

What is the Human Genome Project?

Each of us has about 100 000 individual genes that control all aspects of our development from conception to death. They also combine in complex ways that play critical roles in determining our intelligence, personality and other broad characteristics.

The Human Genome Project is a major international research programme set up to map and decode the ‘book of life’. The human genome (the total genetic content of an egg or sperm cell) can be considered as a book. The ‘book of life’ has 23 volumes. Each volume represents one chromosome of the 23 pairs of chromosomes in human (non sex) cells. The average volume has about 2000 loose-leaf pages, one for each gene. These may occur in small chapters of related genes that are next to each other on the chromosome. One complete set of volumes is passed on by each parent to a child.

"The implications of mapping the entire human genome will be greater than landing a man on the moon: a more important set of instruction books will never be found by human beings. When finally interpreted, the genetic messages encoded within our DNA molecules will provide the ultimate answers to the chemical underpinnings of human existence.”
James Watson
Co-discoverer of the DNA double-helix structure

Barely a week goes past without an announcement of another gene discovery. In 1973, scientists had located just 25 genes.

By the end of 1991, the figure had reached well over 2100. Within the next decade, scientists predict they will have mapped and sequenced all 100 000 or so human genes.

Why is the Human Genome Project important?

“A million people in Britain are members of families affected by genetic disorders and 15 000 babies are born each year with significant inherited disabilities. One in three Britons will suffer cancer - a disease influenced by defective genes, although it is seldom inherited. Many will die of Alzheimer’s and heart disease, both also thought to have a genetic component.”
Steve Connor, Science Correspondent.
The Independent. 18/5/95

‘Breast cancer gene found’

Newspaper headlines, such as the above, reflect the important role gene hunters play. But to talk about ‘breast cancer genes’ or the ‘cystic fibrosis gene’ is slightly misleading; the genes that cause human genetic diseases are actually a vital part of our bodies - but when they go wrong (usually by mutation), some aspect of body function is compromised, and the symptom of the disease becomes apparent. Everyone has a copy of the ‘cystic fibrosis’ gene, for example, but in most people it produces a protein vital to the activities of cells lining the lung. Unfortunately, a small number of people have a defective copy of the gene - so they do not produce a working protein - leading to the classic feature
of cystic fibrosis: the build up of sticky mucus in the lungs.

Genetic disorders place considerable health and economic burdens not only on affected people and their families, but also on the community as a whole. As many of the diseases caused by microbes and poor nutrition have come under control in the developed world, those that are wholly or partly genetically determined are becoming more important, especially among children, as a major cause of hospital admission, disability and mortality. Finding a gene can lead to:

• the development of a genetic test
• a better understanding of an inherited disorder
• the development of specific therapies

Some of the genes which cause or contribute towards particular human diseases have been identified. Once the DNA sequence is known, it is possible to determine how changes in that gene can cause disease. This knowledge creates opportunities for gene therapy and improves possibilities for treatment by other methods through a greater understanding of the disease mechanism. Some human genetic conditions may, in the near future, be effectively corrected for the first time.

Patenting genes

It may seem odd that DNA sequences which are common to everyone should become someone’s property. But if companies are not allowed to patent genes, they argue, there is no incentive to spend money developing gene therapies, since without patents they will be unable to make money from them. Opponents of patenting argue that isolation of a gene is the final step in a long journey, during which many hundreds of people have made vital contributions, yet have no say in the final use of the gene. Moreover the restrictions imposed by patent holders on the use of the gene could, in the long term, hamper the development of therapeutics.

At the moment, genes of known function can be patented - the cystic fibrosis gene is ‘owned’ by the Universities of Michigan and Toronto - but it is not yet clear whether parts of genes or those of unknown function can be registered; the issues are curently being debated.

One might also argue that universities or funding agencies (e.g. medical research charities) should be able to make money from products arising out of research they have funded. One compromise would be to allow the patenting of packages - e.g. gene plus delivery system for a given use - rather than the genes themselves.