Published: May 3, 2007
Updated: May 3, 2007
There is a certain surge of pride that occurs when you see yourself in your child—perhaps your son has his father’s eyes or your daughter her mother’s hair.
These are the traits determined by genetics, free from human dictates. Unfortunately, they are not always so benign.
Every year, a thousand babies in the United States are born with cystic fibrosis (CF), one of the most common inherited chronic conditions. CF presents itself in the respiratory and digestive systems, where abnormally thick mucus interferes with breathing, nutrient absorption, and later in life, reproduction.
In the office I occasionally talk with parents who are worried that their child’s poor weight gain or recurrent cough may signal CF. For parents who have witnessed CF within their own families, concern that their own child has inherited the disease is natural.
Other parents, having searched the Web for a possible cause for their child’s distress, fear that they might be among the millions of people who unknowingly carry a CF gene and pass it along to their child.
While there is no cure for CF at present, the good news is that life expectancy has increased dramatically over the past 40 years.
In this month’s column, Dr. Thomas Murphy, director of the Duke Cystic Fibrosis Center and chief of the division of pediatric pulmonary medicine, explains how far we’ve come in the fight against CF and how much further we’ve yet to go.
--Dennis Clements, MD, PhD
For many parents, news that their child might have cystic fibrosis (known as CF) can be devastating.
One of the more common inherited diseases, affecting over 30,000 American boys and girls, CF results from a gene mutation which causes infants and children to have excessive amounts of thick mucus in their bronchial tubes and intestines.
The lung mucus is prone to infections with drug-resistant germs, while the mucus in the digestive organs prevents nutrient absorption and normal weight gain and can even cause intestinal blockages.
Fortunately, the prognosis for children with CF is far more hopeful than it has been in the past.
In the 1960s life expectancy for an infant diagnosed with CF was only about five years. For children living with CF today, the average life expectancy has increased to 32 years. For newborn babies the odds are even greater, with a life expectancy of 45 years and beyond. While a cure remains elusive, treatment for CF has obviously improved.
The increase in life span can be directly attributed to an organized system of physician care and support and scientific research into the underlying medical problems.
Until the early 1960s, much of the care for CF was improvised. Parents were instructed to go to specialized butcher shops to purchase beef and pork pancreas so their child could ingest additional digestive enzymes, and told to keep infants and small children with respiratory congestion in cribs with tents that provided a personal haze of fine mist (a treatment later shown to provide absolutely no benefit).
In 1965, concerned parents and physicians unwilling to accept the tragic outcomes prevalent at the time established the Cystic Fibrosis Foundation.
Multidisciplinary medical teams consisting of doctors, nurses, nutritionists, respiratory and physical therapists, and social workers were created at accredited CF treatment centers—including The Cystic Fibrosis Center at Duke University, among the first created. Annual scientific meetings were devoted to CF study and research. Principles of medical care were standardized by leading physicians of the time.
Thanks to these efforts, by the year 2010, CF, long known as a disease of childhood, will be predominantly an adult disease. These days most CF children cannot be picked out from their school classmates, and can be found be among the brightest students and even the best athletes.
How is CF identified and diagnosed in children? The process begins with alert parents and doctors who notice these common indicators:
Children with CF symptoms should be referred to an accredited cystic fibrosis center for confirmation of diagnosis and parental education. Siblings of children with confirmed CF, who may be entirely without symptoms early in the course of their own CF, should also be evaluated.
The primary test that determines whether or not a child has cystic fibrosis is known simply as the sweat test. The sweat of children with CF contains an abnormally high salt content (sodium and chloride).
During the test, which takes approximately one hour, the arms are cleaned and a medicine called pilocarpine is applied. An electric current that cannot be felt is applied by a battery-driven metal plate. This allows the medicine to penetrate to the sweat glands and increase sweat production.
The sweat is then collected and analyzed. If the level of chloride salt in the sweat is too high, then the child likely has CF.
In some children, CF can also be diagnosed based on a blood test for certain genetic markers. For a diagnosis to be made, two CF genes must be identified—one from each parent. Over 1,000 such genes have been identified so far, but only 16 or so are responsible for the majority of cases.
The discovery of the CF gene and protein responsible for the disease in 1989 raised hopes that gene therapy could one day be used to treat the disease. While that day has not yet arrived, there is still a spirit of optimism among CF researchers.
Detailed knowledge regarding the CF protein CFTR has emerged in the last 15 years, creating the potential for pharmaceutical breakthroughs. The secrets of predisposition to lung infections are being slowly revealed. Powerful new tools have sped up the production of new drugs, allowing thousands of potential drugs can be screened in one day.
With this technological progress comes a sense that CF will soon become much more controllable, if not curable.
Despite the disappointment that gene therapy has not yet worked, we have made great progress in quality of life and life expectancy through hard work and attention to the many demands of CF therapy—increased meals, enzyme replacements and vitamins that aid digestion, chest physical therapy and special coughing techniques and medicines to clear the mucus, antibiotics, exercise, regular trips to the doctor and countless other requirements.
Our children are like the award-winning bicyclist Lance Armstrong—they are not willing to let the disease control how they live their lives, and they do not give up. Their commitment to fighting the disease, a commitment made by each CF family and our CF Care Center team, will help to keep all children with CF as healthy as possible so they can benefit as adults from the therapies of the future.
-- Thomas Murphy, MD, is director of the Duke Cystic Fibrosis Center and chief of the Division of Pediatric Pulmonary Medicine.
-- Dennis Clements, MD, PhD, is the chief of primary care pediatrics at Duke Children's Hospital.