Cystic Fibrosis and carriers screening

Question

Hello,
Why is it not done automatically as toxoplasmosis or rubella, a search for future young parents (no history in the family) that would check if they are carriers of the gene or not? I think it would be less expensive for the Health Insurance Coverage than paying a lifetime to care for a sick child and would avoid a lot of despair!
A grandmother who has just learned that her grandson has got it and who remains convinced that it could have been avoided by a prenatal test!

Answer

Hello,
You ask a question relevant, timely ... and delicate; that of a mass screening of carriers of a mutation in the cystic fibrosis gene (CFTR gene). The detection of healthy carriers is, in fact, another strategy that the discovery of the CFTR gene has made possible. Its purpose is to detect, in a given population, couples of childbearing age at risk for ¼ of transmitting the disease with each pregnancy. Aware of their risk, these couples could then have access to prenatal diagnosis for future pregnancies. In practice, this screening could be offered to couples wanting a child, but also for couples early in pregnancy. English terminology makes also the distinction between preconceptional and the prenatal carrier screening.
Carrier screening is a health policy that is known to significantly reduce the incidence of disease, as has been demonstrated for beta-thalassemia or Tay-Sachs disease. In the context of cystic fibrosis, a significant decrease in incidence was observed since the introduction of screening in the area of Edinburgh, in a Northeastern region of Italy and in the state of Massachusetts, USA.
The introduction of mass screening has been, in the scientific community in the 1990s, a purpose of heated debates at the point they could lead to the interruption of experimental programs. The reasons against were both technical and ethical. Currently the technical problem is partially solved. It is now not possible in practice to detect more than 1800 mutations identified in the CFTR gene. Using a test kit of thirty most common mutations would not detect all carriers but still over 80% of them in France (with variations according to regions and the distribution of mutations: 90% in Britain). Opponents argue essentially ethical arguments: in particular they question the relevance of wanting to eradicate the disease while the life expectancy of patients is increasing and hopes of efficient drugs are raising. This type of screening is not practiced in France and its implementation is not currently scheduled. The first experience of carriers screening was introduced in Scotland (Edinburgh area) in 1990. Currently, several pilot programs are established in regions throughout the world, including Italy, Australia or Israel. In United States, screening for couples planning a pregnancy and couples early in pregnancy was recommended in 2001 by the College of Obstetricians and Gynaecologists and the College of Medical Genetics. These recommendations have now been updated, and a recent study showed that while most obstetricians offered this screening, many of them had an undeniable lack of knowledge. Apart from experimental studies, the establishment of a mass screening of carriers is therefore a real public health program involving decision-makers (health authorities), payers (social insurance) and expert professionals, firstly, to structure the organization of screening and specialized medical management, on the other, to develop a necessary information and communication plan. In 2009, an international conference dedicated to this subject was organized at the initiative of the European Society of Cystic Fibrosis. The objective was to propose a framework for countries or regions considering the introduction of screening. The paper, published in the Journal of Cystic Fibrosis, recalls the principles of screening, the target population, potential strategies, and emphasizes the technical issues (choice of the panel of mutations, coverage ...) and on aspects of communication.
It is likely that technical developments will allow in the near future a comprehensive study of the genome of an individual, at a cost down so that it will no longer be the limiting element of a program of mass screening for carriage of genes of many diseases. If such a program is not currently on the agenda in France, technical progress in a few years will certainly lead to reconsider the question of its opportunity for ethical reasons ... including, for example ensuring equity of access to technique so that it is not reserved for the wealthiest.
In addition to answering your question, I hope that despite this diagnosis, things are going well for your grand-son and his parents.
Sincerely yours

Gilles Rault, MD and Claude Ferec, MD, PhD, Professor of Genetics

01.09.2011