|Cystic Fibrosis (CF) is a genetic disease that occurs in about 1 in every 3000 live births of Caucasians (and only 1/17,000 African Amercian infants born) in the United States each year, making it the most common autosomal recessive genetic trait that is life threatening. The gene that causes cystic fibrosis is located on chromosome 7, and a child must inherit one copy of the defective gene from each parent in order to get cystic fibrosis. There are over 700 different gene mutations that can cause cystic fibrosis, with the most common being delta F 508.
The symptoms of cystic fibrosis can include a persistent or chronic cough (usually dry and hacking at first and then becoming productive), recurrent episodes of pneumonia and sinusitis (typically with the bacteria Pseudomonas aeruginosa or Staph. aureus), and nasal polyps. Other symptoms can include a meconium ileus (occurs in 10-15% of newborns with cystic fibrosis), rectal prolapse, poor growth, failure to thrive, jaundice, high blood sugar levels, and children with cystic fibrosis may have a salty taste to their skin when kissed.
Children with cystic fibrosis also commonly have problems with maldigestion because of insufficiency of the exocrine pancreas, leading to symptoms of malabsorption and steatorrhea (stools with an increased amount of fat in them) with frequent, large, greasy stools that can have visual droplets of fat in them. This malabsorption can lead to difficulty gaining weight and failure to thrive.
If your pediatrician suspects that your child has cystic fibrosis, then he will probably perform a sweat chloride test. The sweat test measures the amount of chloride in your child's sweat, and is usually above 60 mEq/L in children with cystic fibrosis (although some children with cystic fibrosis have a level between 40-60 mEq/L). Borderline levels of between 40-60 mEq/L are usually repeated and further testing can be done if they persist and cystic fibrosis is suspected.
DNA testing, which checks for the actual gene mutation in a child can also be done and can help confirm a diagnosis of cystic fibrosis if two gene mutations are found. Since not all of the gene mutations are known or can even be tested for, DNA testing may miss 10-20% of children that have cystic fibrosis.
It is also possible to diagnose cystic fibrosis prenatally (amniocentesis or chorionic villus sampling) and by a newborn screen. The newborn screen measures immunoreactive trypsinogen levels, which are elevated in children with cystic fibrosis.
Treatments for cystic fibrosis include nutritional therapy, pancreatic enzyme replacement, vitamin and mineral supplements, pulmonary therapy, including the use of aerosol medications, chest physical therapy (CPT), and antibiotics.
In the future, hopefully gene therapy will allow doctors to repair the gene abnormality that causes cystic fibrosis.
Although cystic fibrosis is a life-threatening disorder, new treatments and a better understanding of this disease has increased the average lifespan into the thirties.
Cystic Fibrosis Internet Resources:
Cystic Fibrosis Recommended Reading List:
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