Cystic fibrosis is a disease that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body. It is one of the most common chronic lung diseases in children and young adults. It is a life-threatening disorder. Symptoms in newborns may include: -Delayed growth -Failure to gain weight normally during childhood -No bowel movements in first 24 to 48 hours of life -Salty-tasting skin -Coughing or increased mucus in the sinuses or lungs -Fatigue -Nasal congestion caused by nasal polyps -Repeated episodes of pneumonia Immunoreactive trypsinogen (IRT) test is a standard newborn screening test for CF. Sweat chloride test is the standard diagnostic test for CF.