Cystic fibrosis carrier testing in early pregnancy by general practitioners.

OBJECTIVE

To assess the feasibility of genetic counselling in general practice by using cystic fibrosis carrier screening at the booking appointment as an integral part of routine antenatal care and as a paradigm for the wider participation of general practitioners in medical genetics.

DESIGN

Maternal testing (male partner tested only if woman screens positive) and couple testing for cystic fibrosis carrier status in the antenatal population attending one general practice and, later, in a further six (outreach) practices also.

SETTING

Two partner urban training practice (pilot practice) in south Manchester, and six north west practices (two inner city, three urban, one rural dispensing).

SUBJECTS

Total practice population of 50,000 (pilot practice plus six outreach practices) with an estimated 500-800 pregnancies per year.

MAIN OUTCOME MEASURES

(a) Proportion of carriers of cystic fibrosis identified, counselled, and appropriately managed within the first trimester of pregnancy; (b) questionnaire and interview measures of patient satisfaction and stress.

RESULTS

Eleven carriers of cystic fibrosis were detected including one carrier couple. This carrier couple, after extensive counselling, elected to have prenatal diagnosis by chorionic villus biopsy. The fetus was homozygous normal.

CONCLUSIONS

General practitioners can successfully integrate genetic counselling and cystic fibrosis carrier screening into the first antenatal booking appointment. When a carrier couple is identified clinical geneticists can help with the discussion of reproductive options, and prenatal diagnosis by chorionic villus biopsy can be completed within the first trimester. The results suggest that general practitioners will have an increasingly important role in medical genetics, subject to continuing evaluation of patient acceptability and stress.