The Major Histocompatibility Complex (MHC) consists of hundreds
of genes on human chromosome 6 that are important in most
autoimmune conditions, when our biological defences turn on our
own systems. The MHC has the major role in type 1 diabetes and
rheumatoid arthritis. The MHC is also pivotal in response to
infection, including malaria and AIDS. Genes in the MHC can
differ dramatically between people, and the differences among us
affect medical events as diverse as tissue transplant rejection,
arthritis, asthma and disease resistance. A detailed study of
this region in different people will shed light on which genes
are most important. "We analysed the entire MHC region in detail
from three individuals that carried different susceptibility to
disease," explained Dr Stephan Beck, leader of the team at the
Wellcome Trust Sanger Institute. Key differences were then
further analysed in a much larger population of 140 DNA samples.
"Within the sea of over 20,000 sequence variations across the 4
million MHC bases,