Posted by Sandy Donchess on October 27, 1999 at 21:05:12:
Wednesday October 27 2:31 PM ET
Scientists Map Immune System Area Of Life Blueprint
By Patricia Reaney
LONDON (Reuters) - An international team of scientists has mapped a region of the genetic blueprint of life, the human genome, that is vital for the immune system and tissue-matching in transplant surgery.
Four genetic sequencing centers around the world collaborated on the mapping of the MHC (histocompatibility complex of genes), which is published in the latest edition of the science journal Nature.
Scientists believe more diseases are associated with the MHC than any other site. MHC genes encode proteins that are essential for the immune system to recognize antigens, or foreign invaders in the body. They also provide each person with their individual tissue type.
Differences in MHC proteins between people are the main cause of rejection in organ transplant surgery.
``A lot of the proteins and systems that are concerned with the immune system are in this region. This is why the international interest was focused here in the first place,'' Roger Horton of the Sanger Center in Cambridge, eastern England, said in a telephone interview.
``This is a small but very important section (of chromosome 6),'' the computer scientist who worked on the project added.
About 40 percent of the estimated 180 functional genes of the MHC on chromosome 6 are involved in the body's immune system -- the biggest concentration in the human genome.
In addition to the immune system genes, the MHC could hold new clues about susceptibility to disorders such as diabetes, rheumatoid arthritis and narcolepsy, a rare disease that causes uncontrollable fits of sleepiness.
The MHC sequencing consortium, a group of scientists from the Sanger Center, Tokai University School of Medicine in Kanagawa, Japan, the University of Washington and the Fred Hutchinson Cancer Research Center, both in Seattle, contributed to the research and the published study.
``One of the really interesting things about MHC is the variation between different people in the sequencing. One of the future projects that will be started will be to look at the variation of this sequence that is published now,'' Horton said.
``We know that if we look at a lot of individuals we will find a lot of small variations between their sequences. What will be interesting will be relating those variations to diseases in small populations.''
Differences in sequences that are found only in diabetes or narcolepsy, for example, could provide scientists with clues about the best treatments for the disorders.
In a separate report in Nature, Jim Kaufman and colleagues of the Institute of Animal Health in Britain sequenced the MHC of the chicken, which contains 19 genes.
Scientists around the world working on the Human Genome Project hope to map the estimated 80,000 or more genes and three billion DNA building blocks in the human genome by 2002.
The blueprint of life will improve scientific understanding about the prevention and treatment of diseases ranging from cancer and cardiovascular disease to asthma and schizophrenia.