Screening probably caused cystic fibrosis drop

By Gene Emery

BOSTON (Reuters) - Massachusetts researchers have seen a dramatic statewide drop in the number of newborns with cystic fibrosis, and said on Wednesday the decline may be due to a national effort to screen for the genetic disease.

Cystic fibrosis or CF, which produces a thicker-than-normal mucus that clogs the lungs and other organs, affects about 30,000 children in the United States each year, or 70,000 worldwide, according to the Cystic Fibrosis Foundation.

It is caused by a small genetic mutation, and children who inherit defective copies of the gene from both parents develop the disease. People who carry just one copy are usually unaware of it.

Newborn screening has been done throughout Massachusetts since 1999. Researcher there have documented a significant decrease in cases after a 2001 recommendation from the National Institutes of Health that a screening test be used for prospective parents to identify carriers of the CF gene.

Dr. Jaime Hale of the New England Newborn Screening Program in Jamaica Plain, Massachusetts, said in a letter to the New England Journal of Medicine that gradual implementation of the recommendation probably produced the decline, first observed in the state in 2003.

"It used to be 30 babies born a year with CF, and now we're seeing, on average, 15," Anne Marie Comeau, deputy director of the program, said in a telephone interview. "This kind of fluctuation over four years would not be expected at all."

Most of the decline among the 80,000 births in the state each year came because of a reduction in the number of cases involving the most common CF mutation.

Comeau said she can only speculate on the reason for the decline because her program only looks at newborn screening, not prenatal testing, pre-conception testing, or any survey of whether women at risk for a CF baby are having abortions.