Cystic fibrosis (CF) is an autosomal recessive inherited disease affecting glands that secrete mucus, sweat etc. mainly in the lungs but also in sinuses, liver, pancreas, intestines, and sexual organs.
Though it is transmitted from parents through genes, the parents themselves need not be having the disease. Its main characteristics are abnormal transport of certain electrolyte ions like sodium and chloride across epithelia, which makes the secretions thick and viscous.
This leads to obstruction of passages in organs like lungs and intestine, and complications thereof.
Incidence of CF is more among Caucasians than in Africans and Asians. It can range from as low as 1 in 30,000 in Asian Americans to as high as 1 in 1300 in Ireland. Males and females are affected equally.
Causes of Cystic Fibrosis
CF is due to a mutation in CFTR gene present on chromosome 7. This affects the movement of water and salt into and out of the cells and also makes the CFTR protein defective.
These changes lead to secretions of glands being dry, sticky and thick, making their clearance from passages, such as airways and intestines, difficult.
Signs and Symptoms of Cystic Fibrosis
CF can manifest in the newborn as intestinal obstruction (called meconium ileus) with symptoms like vomiting, failure to pass stools, and swollen abdomen.
Chronic sinusitis can occur. Nasal polyps (excessive growth of nasal tissue) can cause breathing difficulty. Build up of mucus in the airways allows bacterial infection.
When the airways are blocked, patient will have coughing with tenacious sputum which is often streaked with blood, and difficulty in breathing. Frequent bronchitis and pneumonia can follow, usually due to rare organisms. Eventually there may be respiratory failure.
If pancreas (a digestive organ) is involved, there can be interference with flow of pancreatic juice, leading to malabsorption, malnutrition, growth failure, and inadequate weight gain. Edema (fluid accumulation) can supervene in case of lowered protein levels.
Absorption of fat-soluble vitamins (that is, A, D, E & K) is affected. Involvement of liver can impair blood clotting. In children and adults if intestinal obstruction occurs, there will be decreased appetite, vomiting and abdominal mass and abdominal pain.
Males may be infertile and women will have delayed puberty. Sweat becomes salty due to excessive loss of salt in it. This can lead to dehydration, weakness, fatigue, heatstroke and even death. Nails could be swollen (clubbing). Bone density could be decreased (osteoporosis).
Apart from clinical findings, sweat test should be done to check for excess chloride concentration in sweat. Newborn screening can be done via a genetic or blood test. Amniocentesis and chorionic villus sampling can be used to determine if a fetus has cystic fibrosis.
Treatment of Cystic Fibrosis
There is no cure for cystic fibrosis. Treatment is symptomatic and palliation of complications. Nowadays, due to effective management, infants with CF live into adulthood.
Chest physiotherapy and antibiotics help deal with lung infection. Mechanical ventilation and lung transplantation are required in case of lung failure. Supplements of pancreatic enzyme aid digestion.
Fat-soluble vitamins may need to be replenished. Surgery is required in case of intestinal obstruction. Infertility can be treated with sperm extraction and sperm injection.