Here we have a potential donor that carries a GJB2 mutation which is linked to genetic deafness. There’s actually quite a frequent disease that causes hearing loss, sometimes progressive, sometimes from birth which is not related to any other malformation or alteration and it’s genetic. It’s the most common cause of deafness in the world, genetically. This is what this potential donor could carry and then she carries metabolic disease in mutation which is phenylalanine hydroxylase deficiency. These two diseases are not life-threatening but, clearly, in this case, again you have this information of a person who carries two mutations. This is not what interests us. What interests us is if the partner carries these mutations or not. Your partner does not carry these mutations so usually what we do is we pass these results to a genetic specialist that assesses the remaining risk. Even if your partner is negative and the donor is positive, there is still a risk that the child could be born with one of those diseases. But the risk is usually really low. It depends on the type of tests that you performed because there are tests that are more thorough looking at the gene than others so I cannot really answer you to 100% with the information that I have.
But I think you could go ahead with the protocol without much issue. What we usually do in our centre, after genetic expert consultation, is we discuss the remaining risk with the patients so they can make a decision.
One in 20,000 possibility means that if you had 20,000 children one would be born with this disease. I think this is a risk that you should be able to assume. Of course, each person is different when we usually, for example, when we think about Down’s syndrome when we are pregnant and we do the first-trimester screening test which is done from blood and ultrasound assessment, they advise performing an invasive test such an amniocentesis when the risk is superior to one in 250. If you compare those data, you can see that one in 20,000 is really very low. In our centre, with this rate, we wouldn’t go ahead with this procedure. The risk is never zero.