Immune-related diseases have a strong genetic overlap
8 January 2009
A limited number of genes appear to be involved in the development of
eleven immune-related diseases such as type 1 diabetes, coeliac disease,
Crohn’s disease and rheumatoid arthritis.
This has emerged from an analysis by geneticists at the University
Medical Center Groningen of all globally conducted association studies
of these diseases. The analysis reveals that although the diseases have
different manifestations, they also have a major, comparable origin.
This is a significant advance in our understanding of why patients
can have several diseases at the same time, and why they occur more
frequently within families. The findings were published in Nature
Reviews Genetics in December 2008, in which they investigate the joint
genetic origins of various immune-related disorders.
Between 5 and 10 % of the population have auto-immune and chronic
inflammatory diseases such as type 1 diabetes, coeliac disease, Crohn’s
disease and rheumatoid arthritis. Patients with these diseases often
have problems with chronic infections and their immune systems often
react against their own tissue.
This often leads to chronic infection reactions in, for example, the
joints in the case of rheumatism and the large intestine in the case of
Crohn’s disease. Cases are known where patients have more than one of
these immune-related diseases, or that several family members are
affected. Earlier studies have shown that heredity plays a role in the
emergence of these diseases.
Human DNA has hundreds of thousands of tiny variations, which in most
cases are insignificant. For a number of years now it has been possible
to use these DNA variations to trace genes involved in the occurrence of
all kinds of diseases. This is done by searching for variants in the DNA
that are more common in ill people than in healthy ones.
To this end, about 300,000 variants were analysed for each
individual, a genome-wide association study. This technique has in
recent years been used often for immune-related diseases and as a result
many genes that play a role in these diseases have been identified.
Family studies had already revealed that there was possibly a joint
hereditary basis underlying various immune-related diseases. Researchers
from the department of Genetics of the UMCG have conducted an extensive
analysis of all the genome-wide association studies of these diseases
that have been carried out anywhere in the world.
This resulted in a study of 11 immune-related diseases. It appears
that 23 genes are involved in at least two immune-related diseases; each
of these 23 genes is associated with at least two diseases. In addition,
further research revealed that the function of these genes overlaps.
Many of these genes play a role in the development of the type of
reaction by the immune system (Th1, Th2 or Th17) and which immune cells
are activated as a result (T cells, B cells). This clearly revealed the
way that the immune reaction is disturbed and that also provides
possible reference frameworks for treatment (medication or perhaps
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