Description, signs and symptoms:
Cystic fibrosis is a genetic disorder, which is acquired at conception and therefore present at birth. The disorder is entirely caused by one pair of genes.
People with cystic fibrosis produce abnormally thick, stick mucus in the linings of internal organs such as the lungs and intestines. The most common signs are persistent coughing, excessive sweating leading to salty skin, huge appetite but poor weight gain, and pale, oily, very smelly faeces.
As a result, people with cystic fibrosis are prone to lung infections such as pneumonia. Digestive problems and lack of weight gain are caused by mucus blocking the pancreatic duct, so that the enzymes necessary for complete digestion are not able to reach the intestines.
Growth in some individuals in stunted. Most male sufferers and some females are infertile.
Cause:
Cystic fibrosis is a genetic disorder caused by a pair of recessive genes. Because a recessive gene is involved, the disorder will not appear if the individual has one recessive and one dominant gene. This is because a dominant gene in a gene pair prevents the effects of a recessive one. The gene pair is created at the moment of conception, when a set of 23 chromosomes from the mother is joined with a set of 23 from the father.
In the chromosomes received from both mother and father happen to carry a copy of the recessive gene; the child will have cystic fibrosis. For this to happen, both parents would have to be carriers of the recessive gene. Carriers have the cystic fibrosis gene and also a normal dominant gene – so they do not display any disease symptoms themselves.
Even if both parents are carriers of the cystic fibrosis gene, a child conceived by them will not automatically have the disease. There is a 25% chance of a child being unaffected and not a carrier – having inherited two dominant genes, one from each parent. There is a 50% chance of a child being a carrier (with one dominant and