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[IP] Researchers find a genetic cause of type 1 diabetes and autoimmunity

Found this article very interesting and wanted to share it:

Contact: Diane Duke Williams
email @ redacted
Washington University School of Medicine

St. Louis, Dec. 5, 2000bInvestigators at Washington University School of
Medicine in St. Louis have identified a novel gene that causes an inherited
form of type 1, or insulin-dependent, diabetes and autoimmunity. This finding
might lead to ways to prevent type 1 diabetes.

The research team, led by Talal A. Chatila, M.D., associate professor of
pediatrics, and Anne M. Bowcock, Ph.D., professor of genetics, studied blood
samples from two families affected by a rare disorder that affects only boys
and causes type 1 diabetes and allergies. They found mutations in a gene
located in a region of the X chromosome previously linked to type 1 diabetes.

"This is an example of a single gene defect causing a high incidence of type
1 diabetes in affected children. It provides us with an important tool for
dissecting the genetics of type 1 diabetes and deciphering how the disease
comes about in the general population," said Chatila, lead author of the
study. The results will be published Dec. 15 in the Journal of Clinical
Investigation and are posted on JCI's web site at http://www.jci.org/.

Many children with the disorder, called X-linked autoimmunity-allergic
disregulation syndrome (XLAAD), show the classic signs of diabetes. They also
suffer from chronic diarrhea and eczema. Because XLAAD causes severe wasting,
it often kills babies during the first months of life.

Mutations in a single gene called JM2 cause the disease, the researchers
found. The mutations adversely affect the function of the protein the gene

Identification of the gene, Chatila said, supports the idea that a limited
number of genes are critical for the development of diabetes and other
autoimmune disorders. "Now we need to carefully investigate whether the
pathway that involves this gene is mutated in other patients with type 1
diabetes and whether other genes collaborate with this gene in the disease,"
he added.

Between 500,000 to 1 million people in the United States have type 1
diabetes, which usually begins in children or young adults. It develops when
immune system cells called T lymphocytes kill islet cells in the pancreas
that produce insulin. Insulin "unlocks" the cells of the body, allowing
glucose to enter and fuel them. When cells donbt obtain enough fuel, they
canbt function.

The two families in the study had five affected males. All five suffered from
type 1 diabetes, chronic diarrhea and severe allergic reactions. Other family
members were not affected.

The researchers found mutations in JM2 in all the affected males. This gene
codes for a transcription factorba protein that regulates the activity of
other genes.

Chatila's working model is that defects in the JM2 protein make T
lymphocytesbthe immune cells that mediate type 1 diabetes and abet the
allergybhyperactive and likely to destroy islet cells. "Theybre easy to
activate and difficult to shut down," he said. Understanding how JM2
regulates the immune response and how defects in this protein cause type 1
diabetes will provide important insights into the development of the disease
and into ways of preventing its onset, Chatila added.

Linda V.
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