What is CF ?
Cystic fibrosis or CF is a hereditary disease characterized by recurrent lung infection and delayed growth in children. It is caused by the presence of two defective CF genes, inherited from the parents. Parents are carriers of the disease (CF carriers), having one defective CF gene and one normal gene, and are asymptomatic.
The CF gene defect makes the body’s mucus to become abnormally thick and sticky, which gets trapped in the lungs, pancreas and other organs. This trapped thick mucus in the lungs results in recurrent lung infections which can be life threatening. Moreover, thick mucus in the pancreas blocks the channels transporting digestive enzymes to the intestine. This reduces the absorption of fat and fat soluble vitamins (Vitamin A, D, E and K) from food leading to delayed growth.
The symptoms of cystic fibrosis may vary in intensity among different individuals and hence affected individuals may be diagnosed by the age 2, 18 or later. Some new-borns with CF present with symptoms right from birth that may include no bowel movements as well as no meconium in the first 24 to 48 hours after birth; meconium is the thick dark stool passed by the new-borns in the first few days after birth. Children with CF fail to gain weight, experience abdominal pain with severe constipation along with excessive gas and bloating. Their stools are pale or clay coloured, contain mucus and float.
Prenatal Screening and Diagnosis
Prenatal screening tests are safe procedures used to determine if an expectant mother is likely to have a baby with a particular birth defect. Pre-natal tests to detect CF include chorionic villus sampling (CVS) and amniocentesis.
- Chorionic villus sampling (CVS): Prenatal test done in weeks 10 and 12 of pregnancy in which a sample of chorionic villus – wispy projections in the placenta (structure that develops in the uterus during pregnancy to provide oxygen and nutrients to the growing baby) is removed and tested to confirm or rule out CF in the baby.
- Amniocentesis: Prenatal procedure in which a sample of amniotic fluid (fluid that surrounds and protects a baby in the uterus) is removed and tested to check if the baby has CF.
In newborns, CF is diagnosed by a blood test for immunoreactive trypsinogen (IRT test), a protein produced by the pancreas. Increased levels of immunoreactive trypsinogen may indicate CF, necessitating further tests. In children and adults, CF is diagnosed by Sweat Chloride test. High chloride levels in sweat indicate CF. Apart from these, some additional tests such as chest X-ray, faecal fat test, lung function test, secretin stimulation test, trypsin and chymotrypsin in stool, upper GI and small bowel series of X-rays and pancreatic function test can also be used to detect CF.
Treatment is primarily focused on maintenance of lung function and nutritional therapy. Nutritional therapy involves high protein and calorie diet with vitamin A, D, E and K supplements and pancreatic enzymes. Patients passing hard stool may require specific treatment to soften stools. Lung problems are managed by antibiotics, inhaled medicines, DNAse enzyme therapy and yearly vaccination with flu and pneumococcal polysaccharide vaccine (PPV). Oxygen therapy or lung transplant may be needed in severe cases.
Most children with CF are fairly healthy. However, the disease usually worsens in adulthood leading to disability. Severe lung complications can even lead to death.
Certain risks are common to both the prenatal tests. They include miscarriage, Rh sensitization (occurs in women with Rh negative blood), and uterine infection. Amniocentesis carries additional risks, although rare, such as needle injury, which may occur if the baby moves in the path of the needle used during the procedure. Also, the baby might develop orthopaedic problems if there is chronic leakage of the amniotic fluid after the procedure.