CF affects many organs. However, it can be diagnosed through prenatal or newborn screening before symptoms develop. The initial symptoms of CF that bring most patients to seek medical attention include recurrent respiratory problems and gastrointestinal problems such as difficulty gaining weight and abnormal stools. Some CF patients have “atypical” presentations that involve milder or fewer symptoms. Two-thirds of children with CF are diagnosed by the time they turn one year old. However, the diagnosis can be made at any age, from the newborn period into adulthood.