Carrier Screening May Decrease Incidence of Cystic Fibrosis
Some studies have suggested that there may be a decrease in the incidence of newborns with cystic fibrosis (CF). A new study published in the December 16th issue of the Journal of the American Medical Association has reported that an increase in the number of screened carriers for CF is associated with the decrease in children born with the disease.
Cystic fibrosis is an inherited disease that occurs in 1 in 2,500 to 3,500 newborns. There are about 30,000 in the United States with the disorder that causes a production of thick, sticky mucus, which causes progressive damage to the respiratory system. The mucus also interferes with the digestive system and the pancreas.
CF occurs as a result of a mutation on the CFTR gene that provides instructions for making a channel that transports chloride ions in and out of cells. These ions help control the movement of water in tissues, which is necessary for the production of thin, freely flowing mucus.
Carlo Castellani, MD of the Cystic Fibrosis Center in Verona Italy evaluated the association between CF carrier screening and birth incidence of the disease in northeastern Italy, where neonatal screening has been performed for many years. A total of 779,631 newborns underwent neonatal screening between January 1993 and December 2007. 195 cases of cystic fibrosis were detected.
During the study period, a decrease in CF birth incidence was found, with an average annual percentage decrease of 0.16 per 10,000 newborns. According to the authors, the trend appears to be connected with a decrease in births among those who tested positive for the gene mutation.
In an accompanying editorial by Theodore Liou MD of the University of Utah and Ronald Rubenstein MD PhD of the University of Pennsylvania School of Medicine, experts agree that raising a child with CF offers both rewards and challenges.
They write, “For parents, raising children to adulthood promises numerous intangible rewards but exacts substantial personal and financial sacrifices. The years of effort are punctuated by moments worthy of celebration and others that can only be described as harrowing. Raising and caring for a child with CF poses additional complications in all aspects of personal life for all members of a family, and the desire to avoid those extra costs is easy to understand. On the other hand, the improvements in care have allowed many patients with CF to successfully reach adulthood, complete education, and start families and careers. Thus, a suggestion to avoid all births of children with CF seems distinctly discordant with the increasingly common successes within individual lives affected by CF due to continuing progress in treatment.”
In the United States, prenatal screening for cystic fibrosis is voluntary, and not a part of the routine prenatal process. However, according to the National Newborn Screening and Genetics Resource Center, all 50 states currently conduct newborn screening for cystic fibrosis at birth.
New parents-to-be or those planning a pregnancy who have a personal or family history of cystic fibrosis should be tested. CF carrier testing is done via blood draw or saliva test. Both parents should be tested. If only one parent is a carrier, the children will not develop CF, but there is a 50-50 chance that the child will be a symptomless carrier. When both parents carry the gene, there is a 25% chance, or 1 in 4, that the child will have cystic fibrosis and a 50% chance that the child will be a carrier.