Twenty-two European laboratories are making their contribution to the vast international programme on the Human Genome. Through the project EUROGEM, researchers are drawing up a map of our genetic heritage. This is a lengthy and painstaking task which will enable us to detect predisposition to certain diseases.
Since 1953, the year in which two researchers,
the American James Watson and the Englishman Francis Crick, elucidated
the structure of DNA (Deoxyribonucleic acid) for the first time,
the science of genetics has been engaged in a phase of intense exploration
which is now coming to a climax. This complex molecule in the form
of a double helix is composed of a series of pairs of basic chemical
elements, known as the A, T, G and C bases. DNA is an immense sequence,
written with an alphabet consisting of only these four letters and
displaying a remarkably precise and constant continuity. Inside
the structure of the sequence all the genetic information characterising
every species can be found at very specific sites, and within each
site, the specific characteristics which each individual inherits
(such as colour of eyes, digestive enzymes, illnesses due to genes
whose information is altered, etc.).
Deciphering this information is a far from easy task. A human gene consists on average of 10000 bases and it is estimated that what we call the human genome is made up of between 50000 and 100000 genes. Nevertheless, the differences between two individuals, revealing their two specific genetic heritages, amount to only 1 to 3% of the total information provided by their DNA.
The biological equivalent of the Apollo programme
The world scientific community of geneticists decided to tackle the systematic and exhaustive study of this fantastically complex genetic identity of humanity at the beginning of the 1990s, with the launching of the ambitious International Human Genome project. Regarded by its protagonists as the biological equivalent of the Apollo programme, its objective is to draw up an inventory and to establish, base by base, the tens of thousands of genes which make up an individual.
As part of this huge research programme involving scientists from all over the planet, Europe is giving its support to the EUROGEM project, involving the participation of 22 laboratories from various countries. The aim is to achieve progress in the mapping of the human genome by identifying and disseminating markers in it which can serve to track the DNA molecule. To mitigate the complexity of the complete identification of genes, knowledge now acquired by scientists makes it more and more possible to isolate short sequences of DNA, the specificity of which can be reliably linked to given genetic characteristics. The flagging of such markers throughout the genome, establishing a complete chart of them in the DNA structure, is extremely valuable. In the case of genetic diseases, for example, such marking makes it possible to localise the responsible gene, isolate it, characterise it and find a remedy to the dysfunctioning which it provokes. It also facilitates the surveying of populations of families at risk of developing certain types of illness on account of the presence of a defective gene.
The 23 pairs of marked chromosomes
On the basis of research carried out thanks to the scientific network set up by EUROGEM, two European centres have played a central role in disseminating and coordinating the findings. The Centre d'Etude du Polymorphisme Humain (Human Polymorphism Study Centre) in Paris possessed a valuable DNA resource collected from 40 families followed over three generations, and offered this genetic raw material that had been particularly well studied to the project researchers. Meanwhile, an initial batch of markers assembled by the Imperial Cancer Research Fund (United Kingdom) was distributed throughout the network for topographic detection purposes, the network being responsible for centralising all the results and for collecting new markers identified by research. In the two-year period from July 1991 to June 1993, 23 pairs of human chromosomes were mapped.
For Doctor Niger Spurr, Coordinator and Head of the Human Genetic Resources Laboratory of the ICRF, "The collaboration between these 22 European laboratories has made a significant contribution to the Human Genome Project. It has been possible to draw up a high-resolution human genetic map. Aid from the European Community enables us to pursue this project and to draw up other genome maps. Thanks to this long and painstaking work involving numerous researchers, it will be possible to identify the genes which predispose families, and even whole populations, to develop certain diseases, notably cancers."