Autoimmune diseases could share common genetic etiology

An emerging understanding of this link may lead to important therapeutic advances in diseases such as rheumatoid arthritis, MS and lupus.

By Mark Moran, amednews correspondent. Oct. 8, 2001.

Mapping Disease
As the results of the Human Genome Project began to shake out into clinical applications, this 2001-02 series detailed progress in the prevention and treatment of a variety of diseases and conditions -- both on the near horizon and possibilities far into the future.

From rheumatoid arthritis to multiple sclerosis, lupus and inflammatory bowel syndrome, genetic research is proving that autoimmune diseases may be "all in the family."

By now, physicians are used to hearing that the Human Genome Project has yielded more complexity than simplicity when it comes to understanding most human disease. But experts say that when it comes to autoimmune disease, genetic research is demonstrating a remarkable commonality -- a shared genetic etiology that may clarify the basic pathophysiology of a host of diverse conditions and lead to real therapeutic advances against more than one.

Daniel Kastner, MD, PhD, chief of the genetics and genomics branch at the National Institute of Arthritis and Musculoskeletal and Skin Diseases, says this genetic commonality points the way toward a unifying understanding of the autoimmune diseases -- a view that they are an abnormal inflammatory response to infectious agents or other environmental insults that might be otherwise innocuous to people not carrying a specific combination of genes. And that may someday be good news for doctors treating conditions that have markedly different clinical presentations but still may run in families.

"If there are common pathogenic mechanisms, it means that if you target one you may have a salutary effect on other conditions," Dr. Kastner says. "So our job may be a little bit easier in terms of coming up with efficacious therapeutic targets."

The most recent evidence for genetic commonality in autoimmune disease emerged from a genome-wide study of 257 families with 301 sibling pairs who have rheumatoid arthritis. That study revealed linkages to mutations occurring in broad regions of several chromosomes already linked to other autoimmune diseases: systemic lupus erythematosus, inflammatory bowel disease, multiple sclerosis and ankylosing spondylitis. Among those regions is a dense complex of genes known as the HLA complex, some of which are known to be involved in immune response. [...]

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