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PTD - 199

Test Directory -  Cystic Fibrosis DNA Analysis

Clinical Indications

Current genetic tests in use in the UK detect D F508 plus up to 20 other mutations, which altogether account for 90% of CF mutations in people of northern European origin. The chance of detecting a mutation in both members of a CF-carrier couple is thus about 80%. The specificity of these tests is 100%, that is, any person who tests positive will have the disease, although the severity and course are less predictable.
If both partners in a couple are known CF carriers, they can be offered antenatal genetic testing to determine whether the foetus is affected. This genetic test is virtually 100% accurate. Once a carrier is discovered in a family, other family members can also be offered testing, an approach known as cascade testing. An information sheet is available.

Request Form 

Specific DNA analysis request form


Requests are received from Clinical Nurse Specialists in Genetics (01702) 221409, to whom patients should be referred for assessment. Other requests may be received by GP's as part of a screen for patients undergoing infertility treatment.

Turnaround Time

4 - 6 weeks


Whole Blood


Adult: 10 ml.
Children: 2 - 5 ml.
Babies: at least 1 ml.


PLASTIC Purple top (EDTA) tube


Samples should be taken on a Thursday morning for transport to London via courier. Mix samples thoroughly for 2 minutes to prevent clotting.

Lab. Handling

Samples must be transported to referral laboratory the same day as collection.


Version 1.0 / April 2014                                                                                                          Approved by: Consultant Biochemist