The rules governing "designer babies" could soon be relaxed to allow more screening and embryo selection.
Some argue current policies are inconsistent and confusing
The Human Fertilisation and Embryology Authority (HFEA) is to debate its policy on creating babies who can help sick siblings.
It will consider a doctor's request to select an embryo for a Northern Ireland couple that is a blood match with their son, who has a rare blood disorder.
Currently embryos can only be screened for serious genetic disorders.
Dr Mohamed Taranissi, the director of London's Assisted Reproduction Gynaecology Centre, is pursuing a rule change in a bid to help two-year-old Joshua Fletcher, from Moira, County Down.
Joshua has a potentially fatal blood disorder called Diamond Blackfan anaemia (DBA), which can be treated by using stem cells to stimulate his body to produce healthy red blood cells.
Neither his parents, Joe and Julie, nor his five-year-old brother Adam are close enough matches to give him the stem cells he needs.
But IVF technology could be used to create a baby who can provide these cells.
The plan would be to create up to 12 embryos through IVF treatment. Before implantation the embryos would be screened to find out which has the right genes.
"We only want to give our
son the best chance for a cure," Joshua's father, Joe Fletcher, said earlier this year.
The HFEA has previously ruled that if the level of risk to the newly-created child cannot be quantified, then it is not acceptable to push ahead with its creation.
Anti-abortion and religious groups have opposed a relaxation of the rules and say the ethics must be examined.
Dr Taranissi believes his application will be very hard to turn down
Dr Taranissi told BBC Breakfast: "We are already screening embryos for serious genetic problems... I don't see the difference. What we are trying to do is find an embryo that is a match for a seriously ill child."
But he said that screening and embryo selection should only be allowed when treating medical conditions, not for aesthetic reasons.
He added that the Fletcher's case will be "very hard to turn down" because it is so similar to the case of Raj and Shahana Hashmi, of Leeds.
In April 2003 the Court of Appeal overturned a ban that prevented the Hashmis from creating a baby to help save their four-year-old son.
Although other families have been banned from creating a donor sibling using IVF and have travelled abroad for treatment.
Dr Taranissi said: "You have a child at home that is very seriously ill and you see the pain and agony and know there is a simple treatment out there that will relieve this condition.
"If it is okay for this child or that child how can you deny it to other people?"
HFEA chairman Suzi Leather said the authority was looking at its policy in preparation for the government's review of conception and human embryo and fertilisation laws.
"The HFEA operates in a fast moving area of science so it is important that it continues to keep all its policies under constant review," she said.
On Wednesday it will look at issues surrounding sperm, egg and embryo donation, pre-implantation tissue typing and assessing a child's welfare.
Legal, scientific and ethical issues will also be examined.
But Josephine Quintavalle, founder of the Comment on Reproductive Ethics (Core), described the process of making designer babies as "unethical and unnecessary".
She told BBC News Online that although treating sick children is virtuous, "how you do it cannot exist in a moral vacuum".
"We must fight very strongly to protect the rights of the child that is going to be created," she said.
She is campaigning for an international "bank" of cells taken from umbilical cords and placentas to provide stem cells instead of designer babies.
Ms Quintavalle added: "The HFEA should not be making these decisions. They should be made by the public and parliament."