HapMap will give clues to many common diseases

Oct 27 2005

Researchers say that they have completed a map that charts patterns of human genetic variation in the world population, to better understand human biology, evolution and how to diagnose diseases.

This they say is a major scientific step in the field of genetics and will speed up the search for the causes of common illnesses ranging from heart disease and cancer to Alzheimer's and asthma.

Dr Panos Deloukas, of the Wellcome Trust Sanger Institute says it is a scientific milestone because it now links directly to the human genome sequence and provides a tool to streamline genetic studies.

The Human Genome Project, which mapped the three billion letters that make up the human genetic code, showed that any two people are 99.9 percent the same.

But now an international consortium of scientists has completed a more detailed chart, or HapMap, showing markers of genetic variation, or single nucleotide polymorphisms (SNPs), to explain the 0.1 percent difference.

The HapMap shows SNPs are grouped in neighborhoods, or haplotypes, and are usually inherited as blocks of information.

Deloukas, who worked on the project, says that people around the world are using these markers to carry out genetic association studies to understand the molecular basis of common diseases.

The International HapMap Consortium, a public-private partnership of 200 scientists from Britain, the United States, Canada, Japan, Nigeria and China developed the HapMap using DNA samples from 269 people from Asia, Africa and the United States.

The first phase of the HapMap contains more than 1 million SNPs, an a second phase will add another 2 million.

Professor Peter Donnelly, of Oxford University says the human genome sequence provided us with the list of many of the parts to make a human, but now the HapMap provides us with indicators which we can focus on in looking for genes involved in common diseases.

Using the HapMap, scientists can compare SNP patterns in people with an illness, to healthy individuals, to identify its underlying genetic causes.

Deloukas says the HapMap will also help scientists understand other important processes in biology like evolution, recombination and the forces that have shaped this genetic variation in the human population.

Recombination is the joining of DNA from maternal and paternal lines and the HapMap data will allow scientists to do more detailed studies of inheritance.

It has already revealed that genes involved in DNA repair are not as diverse as those which play a role in the body's immune response.

Deloukas says a number of labs around the world are setting up experiments and in the next 2-3 years a wealth of information should come out of these studies.

He says it is clear the HapMap is going to accelerate the identification of the molecular basis for common diseases quite dramatically.

The first phase of the HapMap is published in the science journal Nature.