What is Cystic Fibrosis (CF)?
CF is a serious life-shortening genetic disease. Generally, people with CF produce thick, sticky mucous in their lungs and digestive tract, causing frequent lung infections and poor absorption of nutrients from food. Other parts of the body can also be affected. Treatment involves daily therapies including physiotherapy and medications (including antibiotics and pills to assist with the digestion of food) and frequent stays in hospital are often required. There is no cure for CF. For more information on CF please visit www.cysticfibrosis.org.au
What causes CF and SMA?
CF and SMA are both genetic disorders. Everyone has two copies of the different genes involved in CF and SMA as we inherit one copy of each of the genes from each of our parents. Sometimes a change is present in a gene (called a mutation), which prevents the gene from working normally. Having a change in one copy of the gene has no effect on your health as you still have another working copy of the gene. Such people are referred to as ‘carriers’. Approximately 1 in 25 Caucasians are carriers for CF while approximately 1 in 37 are carriers for SMA. As shown in Figure 1, when both parents are carriers
for the same genetic disorder, every time they have a child there is a 1 in 4 (25%) chance that child will inherit two changed copies of the gene and be affected with that genetic disorder. Most parents of children with CF or SMA are unaware that they are carriers for one of these conditions before their child is diagnosed. Usually there is no known family history of the disease to warn couples of the risk. This test can identify couples who are at increased risk of having a child with either CF or SMA.
Gene Access, carrier screen
Our genetic carrier screen gives patients information regarding their chances of having a child with a genetic condition like cystic fibrosis (CF), fragile X syndrome (FXS) or spinal muscular atrophy (SMA).
Who should have the carrier screening for CF, SMA or FXS?
Carrier screening is recommended for couples who wish to clarify what their risk is of having a child with one of these conditions. Note – FXS carrier screening is recommended for females as it is inherited in a different way to CF and SMA and only requires that the female have the gene change for there to be a risk of having a child affected by FXS.
What if I have a family history of CF, SMA or FXS?
If you or your partner has a family history of one of these conditions, your chances of being a carrier may be higher. In such cases, it is recommended that you contact your local clinical genetics service for expert advice as testing may be free of charge in this setting.
What if I am found to be at risk of having a child affected with CF, SMA or FXS?
If you are identified as a carrier for one of these conditions, you will be contacted by your doctor or a genetic counsellor to discuss your results in detail. If you are a carrier for CF or SMA, testing of your partner will be offered free of charge to further clarify your risk of having an affected child. For those identified as at risk during an existing pregnancy, testing is available to determine whether or not the developing baby may be affected.
If the developing baby is found to be affected, a genetic counsellor will discuss your options with you, which may include termination of pregnancy. For individuals identified as at risk before they are pregnant, additional options are available to avoid having a child affected with these conditions, e.g. pre-implantation genetic diagnosis through IVF, the use of donor eggs (or donor sperm for CF and SMA), donor embryos or adoption.