It could take years. It could take months.

Diss Mercury: James Taylor with his son Ellis, aged seven. Picture: Taylor FamilyJames Taylor with his son Ellis, aged seven. Picture: Taylor Family (Image: Taylor Family)

It could be fairly minor and be little more than treating a small sore on the skin. But, in the worst-case scenario, it could take over the whole body and dramatically transform how Ellis Taylor looks, with pictures of the famous Elephant Man never far from his family's mind.

For the Taylor family, it is the not knowing how the seven-year-old's illness will develop that makes the devastating recent diagnosis of his condition all the more difficult.

And one of their biggest dilemmas is when to tell Ellis, from Tiptree in Essex, that he has the Neurofibromatosis type one (NF1) condition – and what the consequences could be.

The youngster was found to have the illness which affects one in 20,000 people in November last year, after a chance discovery by a paediatrician suggested he may have the illness.

Grandmother Jenny Jefferson, from Harleston in Norfolk, added that the diagnosis was 'absolutely devastating' for the family.

'It's the not knowing what will happen,' she said.

'We know he's got the first stages. It's just where that leads that we don't know.

'You just can't stop thinking about it. You just want to do everything for him.'

Ellis went for an assessment at Great Ormond Street Hospital (GOSH) in London, with his father James Taylor saying: 'We decided we'd rather know than not know.

'We were hoping it wasn't going to be confirmed. We saw a specialist and they did a blood test, and it came back as positive.

'If the paediatrician hadn't picked it up, we wouldn't have known until something more drastic happened.'

NF1 causes bumps to appear on or under the skin, as well as pale coffee-coloured patches called cafe au lait spots.

The bumps are not cancerous, but depending on where they occur they can cause mobility problems – for example if lumps grow on the spine, feet or fingers – and potentially learning difficulties if they grow near the brain.

Perhaps the biggest effect would be on how Ellis looks.

However the severity of the condition varies from person to person and although Ellis will go for regular check-ups at GOSH, doctors have no way of telling how it will develop – until it happens.

That could be months away – but it may not happen for years. If it does there is, as yet, no cure.

'It's a case of wait and see,' Mr Taylor said.

'He'll have annual check-ups with specialists, just to keep an eye on him in case anything changes.

'That's the hardest thing – the not knowing.

'At the moment he's absolutely fine, with no other signs – but we don't know if that will change.

'You do keep your fingers crossed that it won't affect him too much but you do have that worst-case scenario in the back of your head.

'If you Google it, you will see someone affected quite badly.

'There's not cure and there's nothing you can do about it. You have to stay positive and not let it affect your lives too much.'

NF1 is caused by a genetic mutation, a permanent change in the DNA which makes up a gene, which can be passed from a parent to their child or develop naturally.

Mr Taylor and his wife were tested for NF1 but were not found to be carriers of the condition.

As yet they have not told Ellis about the illness that may change the course of his life, with Mr Taylor saying: 'We don't know when the right time is to tell him

'It is not an easy thing to understand for a seven-year-old. We'll cross that bridge when we come to it.'

Mr Taylor and Mrs Jefferson will embark on a daring skydive at Beccles Airfield on Saturday, July 29.

They want to, in Mr Taylor's words, 'make people aware of the disorder, as there are many people that probably have it without knowing'.

They also hope the money they raise will help to find the all-important cure that may help Ellis in the future.

Both are nervous about the plunge but are eager to do it too help Ellis and others with NF1.

'We know he'll get the best of care but because there's no cure, we'll do it for research – which will help him and others like him in the future, if he ever does need it,' Mrs Jefferson said.

To donate, visit www.justgiving.com/fundraising/jenny-jefferson