Cystic Fibrosis
What is Cystic Fibrosis?
CF begins in infancy or early childhood, and may include pneumonia, breathing problems, lung damage, intestinal problems, and poor growth. While CF treatment has improved, death may occur in early childhood or as a young adult. The average lifespan is about 31 years. Cystic fibrosis (CF) is an inherited disorder which occurs in about 1 in 2,500 live births. CF occurs more often in Caucasian and Jewish individuals than in other ethnic groups.
How is CF Inherited?
CF is inherited as a recessive genetic disorder. Recessive means the effect of the CF gene is only seen when a baby inherits a CF gene from both parents. Parents of a CF baby carry one CF gene and one normal gene and are unaffected CF carriers. When both parents carry a CF gene, they have a 1 in 4 (25%) chance of having a baby with CF with each pregnancy; a 2 in 4 (50%) chance the baby will carry the CF gene, but not have CF; and a 1 in 4 (25%) chance the baby will not carry the gene.
Why Screen for CF?
Screening can identify CF carrier couples, who can then make informed decisions about pregnancy options including having prenatal diagnosis. Both partners can be tested at the same time to receive the most accurate estimate of their risk of having a baby with CF.
Who Should be Offered CF Testing?
- Couples who are pregnant.
- Couples planning their families.
- Individuals with clinical signs of CF or persistent sinusitis, bronchitis, disseminated bronchiectasis, and emphysema.
- Partners of individuals with CF.
- Males with infertility due to congenital absence (or obstruction) of the vas deferens (CAVD), azospermia, or oligospermia.
- Individuals with a family history of CF .
The chance a relative will inherit the CF gene depends on which relative has CF:
| Affected relative | Carrier Chance |
|---|---|
| Brother or sister | 2 in 3 (67%) |
| Niece or nephew | 1 in 2 (50%) |
| Aunt or uncle | 1 in 3 (33%) |
| First cousin | 1 in 4 (25%) |
CF carrier testing for relatives is most reliable if the CF genes are known for the CF relative.
| Ethnic Group | Carrier Chance | Detection |
|---|---|---|
| Caucasian (white) | 1 in 25 | 90% |
| Jewish | 1 in 29 | 97% |
| Hispanic American | 1 in 46 | 72% |
| African American | 1 in 65 | 69% |
- If both parents are found to be CF carriers, prenatal diagnosis can be performed to determine whether the unborn baby has CF.
- Prenatal testing may also be performed when an ultrasound shows an unborn baby has meconium ileus, echogenic bowel, or obstructed bowel.
How is Testing Done?
You may discuss CF testing with your healthcare provider and consider having genetic counseling. The DNA blood test can identify carriers of the 33 most common CF genes. This test will detect 90% of CF carriers in Caucasians, 97% in Ashkenazi Jewish, 72% in Hispanic Americans, and 69% in African Americans. If the DNA carrier test does not detect a CF gene, the risk of being a carrier is reduced, but not eliminated. Testing more CF genes will not significantly improve the detection rate.
Time to Complete Tests:
Carrier and affected individuals' tests are completed within 1 week and prenatal tests will take about 2-3 weeks.
Specimen Transport:
SHIP AT ROOM TEMPERATURE in our kit to:
GeneCare Medical Genetics Center
201 Sage Road, Suite 300
Chapel Hill, NC 27514-7085
By DHL (800) 247-2676 or FedEx (800) 463-3339 priority overnight or by our courier service to reach GeneCare Monday-Thursday. Delivery required within 24 hours. For Friday shipments, mark Saturday Priority Overnight delivery.
Notify GeneCare of shipment date and DHL/FedEx airbill tracking number.
Specimen Collection:
- Call GeneCare at 1-800-277-4363 to discuss clinical indications, current testing, informed consent, fees, and payment method.
- Complete Consent Forms and Laboratory Request. (See Special DNA tests) Enclose family history.
- Label each specimen tube with patient name, birth date, and collection date.
Specimen: Collect 10-15cc of blood in lavender top EDTA tube OR two buccal swabs (1 from each cheek).
Cystic Fibrosis Carrier Screening Policy:
In April, 1997, an independent scientific panel set up by The National Institutes of Health recommended ..."Genetic testing for CF should be offered to adults with a positive family history of CF, to partners of people with CF, to couples currently planning a pregnancy, and to couples seeking prenatal care."
Information provided on this site is for information purposes ONLY. This should not be used as a substitute for professional medical advice, treatment or diagnosis.