Genetic counselling in cystic fibrosis. Results of a survey of 572 families

Disease knowledge in a high-risk population for cystic fibrosis

Cystic fibrosis (CF) has high incidence (1/936 live births) and carrier rate (1/15 inhabitants) in Saguenay-Lac-Saint-Jean (SLSJ). One objective of a major enquiry among several subsets of individuals from this high-risk population for CF was to evaluate the knowledge of the disease and its genetic transmission. The overall score of correct answers pertaining to the clinical signs of CF among medical doctors (general practitioners and specialists) was 42.2 and 65.6%, respectively; it was 84.2% for questions regarding the genetic transmission of CF. The knowledge of the clinical signs was reasonable among CF patients and their parents (about 65% of correct answers), but it was much higher for the genetics (over 88% among parents). Aunts and uncles of CF children were poorly informed of the clinical signs (33.9% of correct answers) but well informed of the genetic transmission (73.8%). Specific subsets of the SLSJ population showed important gaps in the knowledge of the clinical signs of CF but, overall, they were well informed of its genetic transmission.

Cost-benefit analysis of a national screening programme for cystic fibrosis in an Israeli population

The recently acquired ability to identify 97% of CF carriers in an Israeli Ashkenazi population, prompts an evaluation of a nationwide screening programme. In 1993, the programme would first screen and counsel 9,261 parents, then 396 spouses of carrier parents and finally screen 16.5 fetuses where both parents are carriers. Assuming 92% of screened parents choose abortion of fetus screened positive, 2.33 cases of CF will be prevented in 1993 at a direct cost of $781,000. The $326,000 direct costs of preventing a CF case, exceed the lifetime excess direct costs per case of $297,000. However, benefits of screening also accrue to subsequent pregnancies, resulting in a direct benefit ($14.45 million) to cost ($10.39 million) ratio of 1.39/1 for the period 1993-2032. When benefits and costs resulting from mortality changes, work absences and transport costs are included, the benefit ($15.95 million) to cost ($13.88 million) ratio falls to 1.15/1. Benefit-cost ratios are lower for other ethnic groups in Israel, due to lower carrier rates and lower mutation detection abilities. A CF screening programme will increase the freedom of individuals choice, but should be carried out carefully in order to minimize stigmatization and even discrimination against CF carriers.

Reproductive planning after genetic counselling: a perspective from the last decade

Studies from the last decade on factors influencing reproductive planning after genetic counselling were reviewed. Increased possibilities of DNA-analysis and prenatal diagnosis might have brought about a shift in the paramountcy of factors influencing reproductive planning after genetic counselling. In contrast to the literature in the seventies, the magnitude of the genetic risk was no longer found to be one of the decisive factors in postcounselling reproductive planning. Instead, the interpretation of the risk as high or low and the desire to have children appeared to be paramount. The impact of new developments in DNA-analysis in prenatal diagnosis and presymptomatic testing will be an important subject for future studies on factors influencing reproductive planning.

A child with cystic fibrosis: I. Parental knowledge about the genetic transmission of CF and about DNA-diagnostic procedures

In 1984, we interviewed 105 Belgian families with a Cystic Fibrosis (CF) child in order to evaluate their knowledge about the genetic aspect of CF. Three years later, in 1987, they received a mailed questionnaire to assess how well they were informed about the new possibilities of DNA diagnosis. In 1984, three out of the four families were aware of their 25% recurrence risk in subsequent pregnancies. The proportion of correct answers rose to 87% in 1987. The risk that relatives may be asymptomatic carriers was less well known. Only 17% knew that the risk that their own brothers and sisters are carriers of the CF-gene was 1 in 2. The probability that their own healthy children would be carriers of the CF-gene was not known at all. Half of the families who returned the questionnaire thought they were well informed about the new possibilities of DNA-analysis for prenatal diagnosis. The limitations of DNA analysis, however, were poorly understood. The information transfer about the genetic transmission of CF and related topics within the family was also investigated.

Screening for cystic fibrosis among newborns in Norway by measurement of serum/plasma trypsin-like immunoreactivity. Results of a 2 1/2-year pilot project

A pilot project for neonatal screening for cystic fibrosis (CF) by measuring trypsin-like immunoreactivity (TLI) in liquid serum or plasma samples was carried out in Norway from May 1982 to December 1984. A total of 72,320 newborns was screened. Twelve infants were recalled for sweat testing; 11 were confirmed to have CF. One infant had normal sweat sodium and chloride levels and no clinical symptoms. The incidence of CF in this study was 1:6574, and the recall rate for second blood samples was 0.6%. No false-negative cases have yet been reported. The level of TLI was affected by the use of heparin in plasma preparation, being reduced by about 20% as compared to serum levels.