A DEVASTATED family today told of the heartache of losing their 22-month-old "little battler" to a rare form of childhood cancer.

And health experts moved to try and reassure the parents of Nathan Joel Green that his death was not linked to the controversial Measles, Mumps, Rubella (MMR) jab.

Nathan died in his parents' arms last Tuesday from

Haemophagocytic Lymphohistiocytosis (HLH) -- a rare condition affecting just one in 50,000 people, where the body's white blood cells start attacking the bone marrow.

Nathan's parents, Katrina, 24 and dad John, 40, are worried about a link with MMR because he became ill a week after receiving his jab at a local surgery three months ago.

The couple who live with their three other children, John, 13, Steven, seven, and Stephanie, five, in Glenluce Crescent, Shadsworth, Blackburn, said their youngest son became too weak to fight.

But experts said they knew of no research linking the controversial jab with the condition.

Nathan had always been a very poorly child and suffered from an immune system deficiency making it difficult for him to fight illnesses, a swollen liver and spleen problems, learning difficulties and an allergy to sunlight.

His parents, took him to Queen's Park Hospital a week after his jab, where blood tests revealed his white blood count and platelets were dangerously low.

Nathan was then referred to an immunologist at Pendlebury Children's Hospital, Manchester, where it was discovered he had developed HLH.

Nathan underwent chemotherapy at the intensive care unit but Katrina said he eventually "just gave up fighting".

She said: "We delayed giving him the injection because of his weak immune system and our fears over what it might do to him.

"All the doctors and nurses have been great but HLH proved too powerful for little Nathan to fight. The question now is should he have been given that jab."

John added: "The hardest decision was to switch off the life support equipment. I thought he might have cried but he just lay peacefully in our arms.

"And the children had their chance to say their goodbyes."

Nathan's sister Stephanie, suffers from very similar illnesses to her brother. But the family believe she built up a stronger immune system when she contracted Glandular Fever at the age of nine months.

The couple joined family and friends from the Care For Kids play group, Shadsworth Junior and Infant school at St Oswald's Church, Knuzden, yesterday for Nathan's funeral which was conducted by Rev Anne Morris.

Rev Morris said: "I have no words to explain Nathan's tragic death. Although Nathan was ill he was still full of life."

Blackburn with Darwen Primary Care Trust said the matter was an issue between the doctor and the patient and the surgery which gave the jab declined to comment.

Dr John Astbury, a national consultant in health protection, said: "There are only two reported cases -- one in Japan and one in Italy -- of a temporal association between MMR and the development of HHL, which means they happened to develop the condition after having the jab. But there have been no cases in this country and there has been no proven association between the two."

A Department of Health spokesman said: "This is not a link we are aware of. There are occasional odd reactions to immunisation. This is certainly not connected to the allegations that MMR causes bowel problems or autism."

A spokesman for the Medicines and Healthcare Products Regulatory Agency said: "It is always tragic when a child dies.

"One case of Haematophagic histiocytosis suspected to be associated with MMR vaccine has been reported to the MHRA. However, the reporting of a suspected adverse reaction does not necessarily mean that the vaccine caused the condition and other factors may be involved."

A spokesperson for Central Manchester and Manchester University Hospital NHS Trust, said: "HLH is a rare genetic condition which can be triggered by any infection or vaccine as well as medical problems such as arthritis and cancer. We are not able to comment on specific cases"