What is Cystic Fibrosis?
Cystic Fibrosis (CF) is a genetic disease in which
defective transport across membranes causes the
mucus to be thick. This clogs the tiny airways in the
lungs and traps bacteria causing repeated infections
and lung damage. Incomplete digestion also occurs
because of the thick mucus as normal digestive
enzymes are prevented from flowing freely from the
pancreas where they are produced, into the intestine.
CF is a serious but variable disease and requires regular
and continuous treatment. The severity of the lung
disease is the key to the quality and the length of life -
90% die of pulmonary complications. An affected
person may live productively into their 20's and 30's.
How do you inherit CF?
CF is an inherited disease. For a child to be born with CF
both parents must be carriers of the CF gene mistake.
Our genes work in pairs, with a copy of the CF gene on
each chromosome number 7.
Carriers have one faulty copy on one chromosome.
Carriers do not have CF or any symptoms of the disease.
A person affected with CF has two faulty copies, one on
each chromosome 7 received from each parent.
Karyotype
How common is CF?
One in 2500 babies is born with CF. One in 25 Caucasians
are carriers of a CF gene mistake. If a person who
is a CF carrier has partner who is also a carrier, they
have a 1 in 4 chance of having a child with CF.
Do I need this test if I don’t have a
family history of CF?
Yes. Over 85% of couples with children affected by CF
have no family history of the disease because the gene
mistake is silently passed down through generations.
If you do have a family history, then the risk is greater.
Please tell your doctor if this is the case. |
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Why do we offer couple testing?
This is a new test offered to couples by Hunter Genetics.
In the USA, it is offered to all couples either pregnant or
considering a pregnancy. We think couples will want
answers to these important questions:
1. Am I a carrier?
2. Is my partner a carrier?
3. Will my baby be affected?
We are able to test for the most common fault, or
mutation that carriers of CF may have.If both of you
are negative for this mutation the chance of you
having a baby with CF still remains, but is reduced to 1
in 35,000. A small risk remains but because we cannot
check for all the mutations.
If one of you carries the ▲ F508 mutation only, then the
chance of the other partner having a rare mutation,
and then having a child with CF is 1 in 400, and this
would be discussed further.
If both are carriers of the ▲ F508 there is a 1 in 4
chance of an affected child. This knowledge opens up
a variety of options, one of which is prenatal diagnosis.
This could mean chorionic villus sampling to test the
fetus itself for cystic fibrosis. These choices would be
discussed with you, as a couple, to make the decision
that suits you both.
Cystic Fibrosis Carrier Testing
• A simple mouthwash will identify 75% of people who
are carriers.
• 1 in 25 people are carriers.
• Carriers are perfectly healthy.
• If both partners are carriers there is a 1 in 4 chance of
having a child with cystic fibrosis.
• If only one partner is a carrier of the ▲ F508 mutation,
the chance of having a child with CF is 1 in 400.
• Testing is best performed before pregnancy, but can
be performed in early pregnancy.
• Test results take 2 weeks.
• The costs are approximately $40.00 for ▲ F508 testing
and $250.00 for the 20 most common mutations.
Dr Philippa Ramsay MBBS FRANZCOG DDU COGU
Dr Linda Atkins MBBS FRANZCOG DDU
Dr Joanne Ludlow MBChB FRANZCOG FRCOG DDU
Dr Karen Mizia MBBS BSc FRANZCOG DDU
Dr Indika Alahakoon MBBS FRANZCOG DDU CMFM
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