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Duke Researchers Narrow Genetic Roots of Devastating Inherited Lung Disease

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Duke Health News 919-660-1306

DURHAM, N.C. -- By studying the genetics of the rarer
familial form of pulmonary fibrosis, Duke University Medical
Center researchers hope to gain broader insights into the more
common forms of this devastating lung disease, which claims the
lives of half its sufferers within five years.

In the largest U.S. study of families in which more than one
member has been diagnosed with the disease, the researchers
have determined that it appears to strike patients at a younger
age (average age at diagnosis is 58), and that it predominantly
affects Caucasians (92 percent).

The researchers believe that, like most diseases, the cause
of pulmonary fibrosis will likely be a complex interplay
between susceptibility genes and environmental factors, such as
inhaled agents or dusts. While the researchers have yet to
pinpoint a gene or genes for the disease, they say the key to
unlocking the cause or causes will come from sophisticated
analysis of large numbers of affected families.

To date, the researchers have complete genetic and clinical
information on 125 affected members of 38 families; 68 more
families are in various stages of analysis. The researchers are
continuing to look for eligible participants.

The results of the team's study of the first 38 families
were prepared for presentation Friday in a poster session
during the International Congress of Human Genetics in Vienna,
Austria.

Pulmonary fibrosis occurs when the thin layer of tissue
around the lung's alveoli -- the tiny air sacs where gases are
exchanged with the blood -- becomes damaged. The resulting scar
tissue limits the lung's ability to take in oxygen and get rid
of carbon dioxide. There are many forms of the disease, with
the familial form estimated to make up 5 percent to 10 percent
of all pulmonary fibrosis cases.

"This is the only ongoing program in the U.S. that is
systematically studying the genetic basis of pulmonary
fibrosis," said Duke pulmonologist Dr. David Schwartz, who
leads a team of researchers from Duke, the National Jewish
Medical Center in Denver and Vanderbilt University Medical
Center in Nashville, in this National Institutes of
Health-funded study.

"It is our belief that if we can understand the familial
form of the disease, we can make great inroads in understanding
why and how people get the other forms of this devastating
disease," Schwartz said. "Once we get a better handle on the
complex cascade of events that leads to the fibrosis, we should
be able to devise appropriate interventions or determine when
the actual disease process begins and stop it."

Other findings of the study include:

Smoking was identified in 51 percent of cases; Exposure to
environmental agents known to cause fibrosis, such as asbestos,
silica or wood dust, was identified in 22 percent of cases; and
Average age of diagnosis was 58 and average age of death was
61.

One of the great challenges in these types of studies is
actually identifying families and obtaining the necessary
samples for analysis, the researchers said. For this particular
study, patients answered questionnaires, gave blood samples for
genetic analysis and often had various radiologic
examinations.

"In rare diseases like familial pulmonary fibrosis, it can
be a real struggle to find patients," said Dr. Momen Wahidi,
pulmonary fellow at Duke and first author of the current study.
"We have found that our Web site www.fpf.duke.edu, which
describes the disease, has become a great recruiting tool for
patients. We have been hearing from families all over the
world."

Those families who agree to participate in the study can
have all their tests conducted in their home towns. The results
and samples are shipped back to Duke for further analysis.

"We have seen families where two members have the disease,
as well as families where up to eight members are afflicted,"
Wahidi continued. "So there is wide variation in the disease,
but in most cases the disease is fatal in a short period of
time."

Treatment options for these patients are limited. There is
no definitive treatment other than lung transplantation,
according to Schwartz.

"This is such a challenging disease for us as clinicians to
treat," Schwartz said. "Families who participate in this study
are truly noble, because they know it is unlikely they
personally will benefit from the research. We are indebted to
them."

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