Population-based carrier screening for cystic fibrosis in Victoria: the first three years experience.

BACKGROUND: Cystic fibrosis (CF) is the most common inherited, life-shortening condition affecting Australian children. The carrier frequency is one per 25 and most babies with CF are born to parents with no family history. Carrier testing is possible before a couple has an affected infant. AIMS: To report the outcomes of a carrier screening program for CF. METHOD: Carrier screening was offered to women and couples planning a pregnancy, or in early pregnancy, through obstetricians and general practitioners in Victoria, Australia. Samples were collected by cheek swab and posted to the laboratory. Twelve CFTR gene mutations were tested. Carriers were offered genetic counselling and partner testing. Carrier couples were offered prenatal testing by chorionic villous sampling (CVS) if pregnant. The number of people tested, carriers detected and pregnancy outcomes were recorded from January 2006 to December 2008. RESULTS: A total of 3200 individuals were screened (3000 females). One hundred and six carriers were identified (one per 30, 95% confidence interval one per 25, one per 36). All carrier partners were screened, and nine carrier couples identified (total carriers 115). Ninety-six individuals (83%) were carriers of the p.508del mutation. Of the nine carrier couples, six were pregnant at the time of screening (five natural conception and one in vitro fertilisation) and all had CVS (mean gestation 12.5 weeks). Two fetuses were affected, three were carriers and one was not a carrier. Termination of pregnancy was undertaken for the affected fetuses. CONCLUSION: Carrier screening for CF by obstetricians and general practitioners by cheek swab sample can be successfully undertaken prior to pregnancy or in the early stages of pregnancy.

Community-wide screening for cystic fibrosis carriers could replace newborn screening for the diagnosis of cystic fibrosis.

Most babies with cystic fibrosis (CF) are born to parents who did not know they were carriers until their baby was diagnosed with CF, usually by newborn screening. It is only after the birth of their first child with CF that couples are offered genetic counselling and reproductive choices. Most use this information for prenatal testing of subsequent pregnancies. With the high uptake of first trimester screening for Down syndrome (80% in Victoria) most couples have had screening during the CF affected pregnancy. Yet screening for CF carrier status is available, costs are similar to that for Down syndrome screening and CF carrier screening only ever needs to be done once. Waiting for couples to have a baby with CF before they are identified as carriers denies them choice. A national policy on CF carrier screening in Australia, and determination to equitably fund such a programme, is required.