FOR IMMEDIATE RELEASE: Tuesday, April 10, 2007
CONTACT: Ray Fleming, 301-496-8190, <e-mail: flemingr@mail.nih.gov>
SCIENTISTS IMPLICATE GENE IN VITILIGO AND OTHER AUTOIMMUNE
DISEASES
In a study appearing in the March 22 "New England Journal of
Medicine", scientists supported by the National Institutes of
Health's National Institute of Arthritis and Musculoskeletal and
Skin Diseases (NIAMS) have discovered a connection between a
specific gene and the inflammatory skin condition vitiligo, as
well as a possible host of autoimmune diseases.
Vitiligo is a chronic condition in which melanocytes (the cells
that make pigment) in the skin are destroyed. As a result, white
patches appear on the skin in different parts of the body. Similar
patches also appear on both the mucous membranes (tissues that
line the inside of the mouth and nose), and perhaps in the retina
(inner layer of the eyeball). The hair that grows on areas
affected by vitiligo sometimes turns white.
The researchers began a search for genes involved in vitiligo
almost a decade ago with the help of the Vitiligo Society in the
United Kingdom. "In the beginning we were looking for
multiple family members with vitiligo," says Richard Spritz,
M.D., director of the Human Medical Genetics Program at the
University of Colorado at Denver and Health Sciences Center and
lead investigator for the study. The researchers sent a
questionnaire to members of the society, asking them about their
own vitiligo and whether other family members were affected. As
part of the questionnaire, they also asked about other autoimmune
diseases. What they learned was that vitiligo was "very
highly associated" with a number of other autoimmune
diseases, mostly thyroid disease, but also pernicious anemia,
rheumatoid arthritis, psoriasis, lupus, Addison's
disease, and
adult-onset autoimmune diabetes.
That finding prompted the researchers to study families with
multiple affected members and to look for similarities in genes
among those who were affected. By searching the genome, they
discovered a gene, "NALP1", that was key to predisposing
people to vitiligo and other autoimmune diseases, particularly
autoimmune thyroid disease, says Dr. Spritz. "We know that
about 20 percent of people with vitiligo also get autoimmune
thyroid disease, and this gene may be involved in mediating both
of those," he says.
Dr. Spritz says the implications of this finding are exciting. The
identified gene controls part of what is called the innate immune
system, which is our body's first defense against infection, he
says. "When we are attacked by viruses or bacteria, the
innate immune system stimulates the inflammatory pathways and
calls the rest of the immune system to action.
"NALP1" is probably a receptor for bacterial or viral
signals. We don't know what these signals are, but now that we
know what the gene is, we can use that knowledge to search for the
signals that trigger autoimmune disease."
"All autoimmune diseases involve the interaction of multiple
genes and environmental triggers," he continues. "You
are born with your genes, but you are not born with these
diseases. Something happens. We don't know what the triggers are
that start these diseases, but if we did, maybe we could avoid
them or even block the process. In fact, it may even be
possible to actually stop the autoimmune disease," he says.
The most immediate application of this research might be for the
disease that began the research: vitiligo. Doctors usually treat
vitiligo with ultraviolet (UV) light to stimulate skin
repigmentation. Scientists also know that there is one medication
available (approved for treating rheumatoid arthritis) that blocks
an inflammatory pathway thought to be controlled by
"NALP1". The possibility of combining a drug with UV
light to improve vitiligo treatment is intriguing, and Dr. Spritz
is now interested in finding out more about how the medication
might affect people with vitiligo.
NIAMS Director Stephen I. Katz, M.D., Ph.D., calls the discovery
of the "NALP1"-autoimmunity connection an important
advance in the understanding of autoimmune diseases that
collectively affect an estimated 15 million to 25 million
Americans. "The more we understand about these diseases,
including the genes that predispose to them and the environmental
factors that trigger them, the closer we come to better treatments
and even preventive measures," he says.
Additional support for this research was provided by the National
Institute of Allergy and Infectious Diseases, the National
Institute of Diabetes and Digestive and Kidney Diseases, the U.K.
Vitiligo Society and the National Vitiligo Foundation.
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