Carrier couple and pregancy_1

Question

I am a carrier of the Leu732x CF mutation and my husband carries the DF508 one after being tested for 95% of mutations. The amniocentesis was positive for CF in the embryo and the pregnancy (normal conception) was terminated. All test were done at Horemion Laboratory. How severe would have been the disease? If after an IVF a new pregnancy commences, how much positive will the detection of the two mutations in the embryo be? Will we have to do as well an amniocentesis or trophoblast testing for CF?

Answer

Dear friend,
CF is an autosomal-recessive disease, that means, the child is only suffering from the illness of Cf if it has inherited the CF-mutation from both parents: one from the mother and one from the father. If an individual inherits only one CF-mutation and on the other chromosome he does not have a CF-mutation, the person is not suffering from the disease and is called a healthy carrier. This is the case for healthy parents of children with CF. If you and your husband are known carriers of a CF-causing mutation, the chance for every new pregnancy is 25% to suffer from CF, 25% to be healthy and to have inherited no CF-mutation at all and 50% to be healthy but a carrier of one CF-causing mutation.

In case you now decide to become pregnant again via IVF, there are several possibilities. As the 2 mutations of you and your husband are known, the tests can determine practically to 100% if the unborn child will suffer from CF. In case of an IVF, it is possible in certain countries to do a genetic testing of the cells of the embryo, before it is implanted in the female uterus, this is called PID (preimplantation diagnosis). If it turns out, the embryo will suffer from CF, one can decide not to implant this embryo.
If pregnancy occurs spontaneously and the option of PID is not used, then the embryo developing in the mothers’ uterus, can be evaluated via genetic testing in the frame of a chorionic villus sampling or an amniocentesis. If it turns out then, that the child will suffer from CF, there is the possibility not to continue the pregnancy.

CF is a chronic life shortening disease, which at present cannot be “cured” from its roots. It means a lifelong time consuming therapy with inhalations, probably repeated antibiotic courses and for sure enormous efforts and burdens for the whole family. However, even if the mutations predict a “classical picture” of CF with insufficiency of the pancreas and chronic lung disease, the individual course of the disease can differ enormously. Especially the course of the lung disease is not very predictable based on the genetic mutations only. Due to a great improvement in the symptomatic therapy and follow up of CF patients in specialized CF-centers, the life expectancy has improved markedly and is now somewhere in the mid-40ties and 50ties.

I hope this gave you some information to help you further.

Yours sincerely,
Dr. Stavros Doudounakis, Dr. Daniela d'Alquen and Dr. K. de Boeck

29.02.2012