Raj and Shahana Hashmi are fighting through the courts for their son Zain's right to have a controversial, but life-saving, treatment.
The Hashmis say they draw strength from their son
The couple want to use an embryo screening technique so they can have another child who is an exact tissue match for four-year-old Zain, and who could be the bone marrow donor he desperately needs.
Zain has the rare blood disorder thalassaemia and urgently needs a transplant, but no suitable donors have been found.
He can be kept alive through blood transfusions but over time, the amount of iron in the body can build to dangerous levels.
This week, Raj and Shahana faced the media once again.
They are going to the Court of Appeal in a bid to overturn a block on the treatment imposed by the High Court last year.
Mrs Hashmi, who runs the Zain Bone Marrow Foundation, said for Zain, said they are inspired by their son's personal battle against his illness.
Shahana Hashmi said: "Zain has a right to life and we want to ensure that he gets that right."
"He's very bright and knows what's going on. He's a real live wire."
But she added: "How is one child supposed to deal with so much in his short life?"
The couple from Leeds, who have four other children, aged three to 18, are united and unshakeable in their determination to tackle whatever obstacles are placed in their path, despite also having to cope with the normal demands of family life.
Their eldest child is currently studying for her AS levels, while her 16-year-old brother is set to take his GCSE's this year.
Mr Hashmi said this latest court battle was simply another challenge to overcome.
"It's another block that's been put in our path, another bridge to cross."
The Hashmis have found themselves as the spokespeople for other parents in their situation.
Mr Hashmi said: "Since we came into the spotlight two years ago, numerous other couples have come to us.
"We know of at least seven."
Mrs Hashmi said she spoke at a meeting recently, where there was a roomful of parents in the same position as them.
She said: "They put us on a pedestal. But we are just parents desperately seeking to save our son's life."
After Zain was born, the couple did have another child naturally. But Harris, now three, is not a match for his brother.
Mrs Hashmi then fell pregnant again, but the baby was diagnosed as having thalassaemia, and the couple decided to terminate the pregnancy.
Zain Hashmi with his mother Shahana, who says he is 'a real live wire'
Her husband said: "That was the most heart-rending decision we've had to make."
After the Human Fertilisation and Embryology Authority gave the go-ahead for the embryo screening treatment, in February last year, the couple underwent two cycles of treatment.
In the first, no embryos were a match for Zain. They were frozen, and the Hashmis say they will donate them to couples needing fertility treatment.
The second produced five healthy embryos, two of which were perfect tissue matches for Zain.
But the first failed to develop before it could be transferred into the womb and Mrs Hashmi failed to become pregnant with the second.
"It was very close. We could almost touch it," she said."
No other option
If they fail in their court case, the Hashmis say they will continue to fight, and will take their battle to be allowed to have the treatment in the UK to parliament and the European Court.
But they may not be able to wait for the outcome of the UK legal process.
Shahana, 38, knows her fertility is declining because of her age, so the couple would also consider going abroad for treatment.
Mr Hashmi said a failure to persuade the court would mean Zain's very painful treatment would have to continue, but there is no other option which could provide a cure except a bone marrow transplant.
"As parents, we would try to alleviate his suffering, but we would just have to watch him die."
IVF expert Dr Simon Fishel, director of CARE at The Park Hospital in Nottingham who has been treating the Hashmis, told BBC News Online: "The Hashmis call themselves a normal family. In one way, they are normal. But in another, they are remarkable."
But he added: "We should not underestimate how difficult it is to have some group take up a judicial review to stop them in their tracks."