As the public is to be asked whether screening of embryos should be widened, two women whose sons were born with incurable diseases share their views with BBC Breakfast.
Melanie Denning and Jane Field both support embryo screening
One of them, Melanie Denning, is currently undergoing embryo screening for cystic fibrosis, after her son Owen, five, was born with the hereditary disease.
Jane Field's seven-year-old son Murray was born with Duchenne muscular dystrophy. It cannot be screened for.
Owen was born as a result of IVF, but we didn't know we had CF in the family until we had him and he was diagnosed at four months old.
But since then we have been able to go through the PGD (pre-implantation genetic diagnosis) programme at UCH (University College London) where we have had two attempts at PGD where they actually screen the embryos.
This is where they can screen the embryos and put back either ones that are just carriers or ones that are free.
We really would like to provide a sibling for Owen and to make our family bigger if we can. And, you know, we would love other people in future to have this possibility for other conditions. So I am very much in favour of the work.
While the HFEA (Human Fertilisation and Embryology Authority) have obviously said they want to consult with everybody, when they consult people who don't even have children with these conditions, I don't really know how people can make a judgement, if you are outside the situation.
I worry that the moral majority will drown out the voices of people like us.
We need that chance to give Owen a sibling, who doesn't have the disease and could provide him some support and comfort when he's older - because CF is a degenerative condition, so although he's well now he won't be long-term, and when he's getting sicker is when we're going to be older, so that's the brutal reality of it.
I am absolutely in favour. I mean Duchenne muscular dystrophy is one of the most hideous diseases.
Not because of the death of a child, at 21 or 22, but because of the process of death which is absolutely terrible really because you have a bright and beautiful child, like my son, with a bright brain, who gets trapped in an increasingly useless body.
I get extremely angry when I hear about stem cell research not being supported - it's our only hope.
We have a good genetic patch programme that is really hopeful and if we don't get that money, and that funding, and people don't move forward, there will be no hope for the two boys that are born and die every week of this disease.
I am not a genetic carrier; 40% of cases of Duchenne muscular dystrophy occur just like that, while 60% are genetic carriers through the female line.
But if I had been able to screen Murray I would have certainly terminated him.
Now he's my beautiful child and I couldn't imagine doing that. But that's because I know the child.
When he was an embryo, do you think I would have given that disease to anybody? With no hope of a cure of treatment? No.
How do we deal with life with the disease now? You either, I think, fall into a puddle. Or you pick yourself up, dust yourself down and you get on with it.
That is what you have to do. He's a glorious boy, we revel in every single moment we have with him. I don't look to the future, I look very much now and we live our lives.
We do things, and hopefully he will do more in his life, and the hope is that there will be a treatment - there won't be a cure perhaps - but there will be a treatment.