WTC workers who lack gene prone to lung injury

By Martha Kerr

SALT LAKE CITY, Utah (Reuters Health) - Among fire fighters and other first responders involved in the rescue effort at the World Trade Center in New York on September 11, 2001, a more rapid decline in lung function is being seen in those with a genetic deficiency.

The discovery of this deficiency in the gene that codes for the enzyme alpha-1 antitrypsin (AAT) was reported here at CHEST 2006, the annual meeting of the American College of Chest Physicians.

Approximately 2 percent of the general population has some degree of AAT deficiency. "It's a variable disease" with different degrees of expression, depending on the number of gene copies present, Dr. David Prezant explained during his presentation. Individuals with a severe gene deficiency produce very low levels of the enzyme, while those with a more moderate gene deficiency have moderately low levels of AAT.

Prezant, of Montefiore Medical Center in New York City, and colleagues have been conducting blood and lung function tests on 151 fire fighters who were involved in the rescue effort at the WTC when the towers collapsed and for many days following.

"Some rescuers have had a significant loss in lung function since 9/11, while others have had very little," Prezant told Reuters Health before his presentation. "We are looking at a number of genetic factors that might be involved in the accelerated decline. The AAT test is a simple blood test, and this is the first factor we have identified."

Ninety of the rescuers have had AAT blood levels measured. Of these, 79 have normal levels, 7 have a partial gene deficiency and produce moderately low AAT levels, and 4 have a severe deficiency and produce very low AAT levels.

The 11 fire fighters with AAT deficiency have had faster declines in lung function than those with normal levels. Those with severe AAT deficiency have had the most rapid decline, Prezant reported, while those with moderate AAT deficiency show a more moderate loss of lung function.

All of these individuals had normal lung function prior to the attack.

"Alpha-1 antitrypsin deficiency is commonly associated with emphysema and other airway diseases like COPD," Prezant noted. It is involved in the inflammatory process and it may be a cause of the World Trade Center cough, which meets the definition of chronic cough syndrome, he said.

Based on what is known so far, physicians should treat these patients according to the recently issued guidelines for chronic cough syndrome, Prezant said, and "stay tuned to the literature for other developments."

AAT deficiency should "absolutely not" be used in screening at this point, Prezant emphasized. "This condition is too undeveloped. We need the whole genetic profile. This is just the first one to jump out at us."

"We are looking at a whole spectrum of other possible genetic links," he added. For example, AAT deficiency may cause disease in conjunction with other genetic markers that have not yet been identified.