This is Glenn Stafford's big week. On Friday the film Lorenzo's Oil opens in Britain and Glenn will be famous. Not as famous as Lorenzo Odone, the boy from Washington DC whose story is related in the film, but famous enough for a 10-year-old from Stanford le Hope in Essex.

Glenn, like Lorenzo, may possibly owe his health to the oil in the title of the film. But unlike Lorenzo, Glenn will have to wait until the very end for his moment of glory. As the credits roll he is on screen among a mosaic of images of boys, toddlers and teenagers, full of fun, swimming and playing sports, who all take Lorenzo's oil.

This is a vegetable oil derived from rape seed which, it is claimed, stops the onset of a rare but fatal disease, adrenoleukodystrophy (ALD), which in boys leads to degeneration of the nervous system. In children who have already developed the disease, the oil is reported to have brought improvements. The film is a largely accurate account of how Lorenzo's parents, Augusto and Michaela Odone, a couple based in the United States with no scientific background, discovered the oil.

Their search was first reported in the Independent in October 1989. It is a wonderful human story, a classic tale of triumph over tragedy - a dying child and desperate parents who refused to accept the perceived wisdom of the medical establishment, which said nothing could be done. But their story does not have a tidy ending, a fact that Hollywood understandably chose to ignore.

Christine Stafford, Glenn's mother, does not view Lorenzo's oil as a miracle cure - but she is not prepared to risk refusing it. Glenn, like Lorenzo, inherited the defective gene that causes ALD from his mother. There is a 50-50 chance that he will develop the severest form, in which there is a build up of a fat in the blood that destroys the white matter of the brain and the myelin sheath surrounding the nerve fibres.

The film implies that Lorenzo's oil is the answer to ALD. The Odones clearly believe it is, and say that Lorenzo's condition has improved. He is still bed-bound and cannot see or hear, but he can now communicate with his parents by moving his fingers to indicate yes or no.

However, the jury is still out. It has yet to be proved that the oil can halt the onset of the illness. Dr Stuart Green, a paediatric neurologist who heads a team conducting a trial at the Birmingham Children's Hospital of Lorenzo's oil as part of a diet in 10 to 20 British ALD children, says: 'We just don't know yet. There is good evidence that you can lower the abnormally high fatty acids in ALD with the oil. We need to ascertain whether you can do this, if it has any serious side effects and if it is effective in treating the disease.'

But any trial is complicated by the fact that ALD is notoriously variable, he says. 'Not only in its time of onset but also in its format. Some people do not develop it until adulthood, some never develop it and others have only a milder form.'

Until medical science provides the answer, Glenn will continue to take two-and-a-half spoonfuls of Lorenzo's oil every day after breakfast, as he has done for three years, because it at least offers hope.

The Stafford family is only too aware of what the future could hold. Barry, 12, Glenn's brother, has ALD. An apparently healthy little boy, his symptoms started when he was seven years old. He became progressively quieter and more withdrawn and now he is blind and deaf, unable to move, and needs round-the-clock care.

Mrs Stafford says: 'I've got one son with ALD. Lorenzo's oil was too late for him but I've got another son whom I'm determined to keep . . . There is a chance that Glenn wouldn't become ill anyway, but I'm not going to take that chance so he'll carry on with the oil.'

The oil does have side effects, she points out. Glenn bruises and bleeds easily because it affects his blood platelets (cells involved in clotting), but she says it is a small price to pay if the oil works. Barry takes the oil, too, but, his mother says: 'To be honest Barry has not improved. If anything he has worsened. It maybe helped him 'plateau' and slowed down the disease process, but that is all.'

Mrs Stafford is bemused by the fuss surrounding the film. She has to cope with the reality of ALD every day, caring for Barry and trying to lessen the burden on Glenn, who has watched his adored brother degenerate.

'We have discussed everything with him because he's got to know, when Barry goes. He's very protective of him but he is vulnerable, too. He gets upset because he doesn't want Barry to die.'

Looking after Barry at home is tough, although he attends a special school in Basildon during the day. He can no longer be fed by mouth and receives a nutrient infusion overnight. He is prone to constant infections but he is, according to his mother, a fighter and the rewards of caring for him are great. 'Getting something out of him is difficult but we can comunicate with him in our own way. He still has a wicked sense of humour and when we get a really good day with him it is brilliant.'

The fact that he has survived longer than most boys with ALD may 'possibly' be due to Lorenzo's oil, she says, but more likely her family is responsible. 'I've tried to keep things as normal as possible and I think that is why he has got that bit more of a fight in him,' she says. 'He still has a good quality of life.'

Later this week she will attend the charity premier of the film with Glenn. It is in aid of The Myelin Foundation, Augusto Odone's current project which seeks to find a way to restore Lorenzo's damaged myelin. Again he is attempting to speed up the progress of medical science by bringing the top researchers together and funding their projects. The Odones' contribution to understanding and possibly treating ALD should not be underestimated, but only the painstaking application of science will determine the true worth of Lorenzo's oil.

(Photograph omitted)