A woman is living under the shadow of a cruel disease which claimed the life of her grandfather, mother and uncle.

Former Huddersfield teacher Jackie Harrison has a 50-50 chance of inheriting Huntington’s disease in what she describes as the “toss of a genetic coin.”

Jackie Harrison, 50, is the carer and legal guardian of her younger brother Mark, who also has the disease.

Jackie Harrison of Baliff Bridge, with her brother Mark who has Huntington's disease. Pictured with her dog Sybil.

Huntington’s is a degenerative condition that affects muscle co-ordination and movement and causes mental decline and psychological problems.

It is a disease caused by a faulty gene which, since the 1990s, can be detected by a simple blood test.

Jackie, who taught part-time at Huddersfield Technical College, has already out-lived her mother and uncle but is refusing the test.

“I have lived with this all my life and I expect to get the disease,” she said. “Knowing wouldn’t make any difference.”

Three generations of Jackie’s family – grandfather Roy Iles, mum Jean, uncle Barry and brother Mark, 42 – all succumbed to the disease.

Jackie Harrison's mum Jean (left) and grandmother Edith. Jean died of Huntington's disease aged 48.

Jackie was just 12 and Mark six when their mum died aged 48. She spent the last few months of her life at the former Storthes Hall psychiatric hospital, the only option at the time.

Jackie said: “It’s a cruel disease. By the end you can’t eat, swallow, communicate or move. It’s very, very hard to watch. To have one person in your family go through that would be bad enough let alone generation after generation.”

Roy and Edith Iles, Jackie Harrison's grandparents on their wedding day. Roy later died of Huntington's disease.

There is no timescale for when the disease will strike and Mark developed symptoms when he was about 30. Now he has his good days and bad.

Jackie, now a full-time carer for Mark, has devoted much of her time to raising awareness of the disease.

She and Allan Adams, whose son has the disease, teamed up to make a moving video about her family.

Jackie Harrison's uncle Barry who died of Huntington's disease aged 43.

Entitled: Give a Toss for Huntington’s Disease it tells the family’s story from the marriage of her grandparents Roy and Edith in 1929 through the deaths of their children Jean and Barry, 43, down to Jackie and Mark.

Jackie lives under the toss of a coin and, without taking the test, remains a “female at risk.”

The video, just nominated for an award, was a way of ensuring the memory of her family lives on.

“They are not just statistics, they had real identities. They were people with ambitions, loves and likes not just dots on a page or patients who died in an asylum,” said Jackie.

“The odds are 50-50, so literally like the toss of a coin, only it can be heads five times in a row or tails five times. It’s very much been a hidden disease in the past, maybe because people have not wanted to talk about it or because it was misdiagnosed.

Jackie Harrison of Baliff Bridge, with her brother Mark who has Huntington's disease. Pictured with her hand made dogs to raise money for charity.

“People have to be 18 before they can take the test but that is only after extensive counselling. You’re always looking out for the signs. If you drop something is it the onset of the disease or is it just clumsiness?

“I think only around 20% of people take the test. If it comes out tails your fate is sealed. They aren’t able to map the disease or give a timescale but if you have the gene you know what will come in the future.”

Jackie was brought up by her grandmother and became Mark’s legal guardian aged 18 after her death.

Jackie Harrison's brother Mark, who is battling Huntington's disease, has a love of animals.

Mark has a degree in English from the University of Leeds, has read all Shakespeare’s plays and has a degree in history from the University of Huddersfield.

But before he could embark on a career he developed Huntington’s. Now, as the video says, he will lose the ability to talk, walk, eat and swallow. He may also lose the ability to think.

“He varies from day to day,” said Jackie. “He has to have his routine and has obsessive behaviour. He loves animals and we try to get out as much as we can but we take it one day at a time.”

Jackie, who completed a Master of Arts degree at the University of Huddersfield in 2013 exploring the concealment of Huntington’s, said it felt “weird” to have out-lived her mother but she had no intention of taking the test.

She has a partner, Tony Surr, but never had children. “People who have taken the test have regretted it,” said Jackie. “Once the genie is out of the bottle there’s no going back.”

Jackie Harrison of Baliff Bridge, making Hounds for Huntington's.

Jackie and friends have embarked on a fundraising drive which has raised £1,000 for the Huntington’s Disease Association. Called Hounds4Huntingtons on Facebook, the group makes stuffed dogs – inspired by Jackie’s border terrier Sybil – in exchange for a donation to the charity.

The cute pooches are loved by dog owners and Jackie said: “I didn’t know I had the talent – and I don’t really – but people seem to love them.”

To contact Jackie e-mail jsharrison@hotmail.com.