Cystic fibrosis is an autosomal recessive trait on chromosome 7. This
disorder affects chloride transport resulting in abnormal mucus production.
This lifelong illness usually gets more severe with age and can affect both
males and females. Symptoms and severity differ from person to person. Cystic
fibrosis is the most common fatal inherited disease among whites and the major
cause of chronic lung disease in children. 50% of people are expected to live
to be 30, but a majority die before age thirteen. 1:2000 whites have cystic
fibrosis, 1:17000 blacks, 1:6000 live births, 1:2500 Americans, and 1:20 is a
The genes are inherited in pairs, with one gene coming from each parent
to make the pair. Cystic fibrosis occurs when both genes have mutations. A
person with cystic fibrosis receives one cystic fibrosis gene from each parent.
The parents of a child, with cystic fibrosis, each carry one nonworking copy of
the gene and one working copy of the gene. The parents are called cystic
fibrosis carriers, and because they have one working gene they have no symptoms.
Carrier parents have 1:4 chance to have a child who is a noncarrier of cystic
fibrosis, a 1:2 chance to have a child who carries the gene, and a 1:4 chance
with each pregnancy to have an affected child. If you have a son or daughter
with cystic fibrosis, then you have a 1:1 chance of being a carrier. If you have
a brother or sister with CF, you have a 2:3 chance of being a carrier. If you
have a niece or nephew with CF, you have a 1:2 chance of being a carrier. If
you have an aunt or uncle with CF, you have a 1:3 chance of being a carrier and
a 1:4 chance if you have a 1st cousin with CF.
Cystic fibrosis affects the lungs in particular. The secretions are
thick and sticky rather than thin and watery. This interferes with the removal
of dust and germs. It can lead to lung infections and even chronic lung damage.
Air passages become clogged with mucus and there is often widespread obstruction
of the bronchioles. Expiration is especially difficult. More and more air
becomes trapped in the lungs, which results in obstructive emphysema.
Atelectasis can occur leaving small areas collapsed. Eventually the chest
assumes a barrel shape. The right ventricle, which supplies the lungs, may
become strained and enlarged. Clubbing of the finger and toes may occur due to
the compensation response indicating the chronic lack of oxygen.
Cystic fibrosis affects the pancreas. The mucus clogs the duct and
blocks the transfer of enzymes from the pancreas to the intestines. These
enzymes are needed to break down food that is necessary for proper growth and
weight gain. The mucus in the digestive tract blocks the absorption of
necessary nutrients. This is why there is often no weight gain despite good
appetites. This can be associated with failure to thrive. The buttocks...