Monozygote twin - CF testing

Question

Without any history of CF in our families, we decided for my husband to get tested for 89% of the CF mutations. Given the fact that he has a monozygote twin, who does not have children yet, we believe that, due to almost identical DNA, the genetic testing will cover him as well. Is this true? Can the CF mutations be influenced by environmental factors?
The results were negative for any pathogenic mutations.

Answer

Dear friend,
Indeed, since the twins are monozygote, the genetic material is identical, so the test does cover your brother-in-law, to the extent it covers your husband.
The environment does not create mutations. In a person with CF the course of the disease can be influenced by the environment through factors, such as smoking, therapeutic treatments, physiotherapy, nutrition, exercise and vaccination.
Your husband has been tested with negative results for a great many number for CF mutations, so the possibility of having a baby with CF is greatly reduced. This possibility is even further reduced when tested for a greater number of CF mutations.
Yours friendly,
Dr. Stavros Doudounakis

22.12.2015