Cystic fibrosis is an inherited, genetic condition common in people of northern European and Ashkenazi Jewish ancestry. People with cystic fibrosis have progressive lung disease that causes frequent infections and trouble clearing the airways. They also may have gastrointestinal problems and other complications. It is estimated that about 1 in 25 descendants from northern Europe or Jewish ancestry are carriers for cystic fibrosis. Carriers are unaffected individuals where one gene causing CF---the CFTR gene---is defective, while the other copy of the gene is normal. Children are affected with CF when they have inherited two nonworking CFTR genes, one from each parent.
Prenatal Signs
Some fetuses affected with cystic fibrosis have a finding called "echogenic bowel," which is seen as a bright spot in the bowel on ultrasound. An echogenic bowel is seen in unaffected fetuses, however, it is identified more frequently in those who have CF.
Abnormal Newborn Screen
Newborn screening tests babies for conditions that may be present for which identification and prompt intervention improve the outcome of the disease. Newborn screening for cystic fibrosis is done in every U.S. state. A positive screen for CF does not mean a child has the disease. Very accurate testing is done after a positive newborn screen to determine if the child has cystic fibrosis or not.
Salty Tasting Skin
A common feature of cystic fibrosis is having a high chloride concentration in the sweat. This causes very salty tasting skin and can be a symptom of CF. A specific test, called a sweat test, measures the concentration of chloride and is used to test a baby for cystic fibrosis.
Meconium Ileus or Greasy Stools
Meconium is a baby's first bowel movement. Meconium ileus is a condition where, due to the characteristic thickening of stool in CF, the meconium gets stuck in the small intestine and cannot be passed. Occurring in 20 percent of babies with CF, this may be the first sign in a child. Greasy, thick, foul-smelling stools are another symptom of cystic fibrosis.
Poor Weight Gain
In people with CF, the pancreas works improperly, causing poor absorption of food. Therefore, newborns with cystic fibrosis have a difficult time gaining weight. There are many other reasons a child may not be gaining weight. In a child who is growing slowly, CF testing is commonly done.
References
- Lancet; Cystic Fibrosis; Brian O'Sullivan and Steven Freedman; May 2009
- "Thompson & Thompson Genetics in Metabolism, 7th Edition"; Robert Nessbaum; 2007
