If the devil could have picked an illness to call his own, this would be it," says Cath O'Donnell. She had to watch as her husband David and both her daughters were struck down by Huntington's Disease, a cruel, hereditary, neurological disorder.

David, her husband of 36 years, can't talk, eat or walk. He is fed through a tube in his stomach, trapped in his own body but with a sound mind and perfect understanding. Now, after 17 years of devoted caring by his wife, he is in a care home at Peterlee.

Cath, 57,weeps for him and for their girls who inherited the gene from their father.

"I feel for the girls. They know what's coming. I can't even begin to imagine what that's like," she said. "It must be absolutely horrendous. I can't do anything for them. There is hope – if a cure is found it probably won't benefit David but I hope it will benefit the girls."

Louise, 30, was diagnosed with the disease three years ago. Cath says: "I was absolutely devastated. It's like looking at David 15 years ago."

She had to give up the job she loved, working in the chief executive's office for the former Orange call centre at Peterlee, and now lives in a bungalow with a good care package in place.

Cath still hadn't recovered from the devastating blow of Louise's diagnosis when Lyndsey, 32, was diagnosed last November.

Cath weeps openly. She is heartbroken and says if they had known that the gene was in the family they would never have had children.

She has not told her husband that Louise and Lyndsey have the disease.

"David doesn't know about the girls," she said. "The only thing he has ever said is 'I don't care if I have to get it as long as I don't hurt my girls'. He would be devastated "

Louise is struggling and finds it hard to walk as the disease affects balance. Lyndsey is still able to work in accountancy and is in a long-term relationship.

Louise was 14 and Lyndsey 15 when their dad was diagnosed with the disease at the age of 42. It was a bombshell. David was the 13th of 14 children and three have already died from the disease – two brothers and a sister. Eight have been cleared and three haven't taken the test.

A niece and a nephew also have it.

When Lyndsey told her mother she also had Huntington's, Cath was broken, grief-stricken for the girl she had hoped and prayed would be all right.

Recalling that terrible moment, Cath's cry from the heart was: "It isn't fair." And she admits she thought: "Why me?"

She says: "I could lie back and die or I can fight and I think the family is worth fighting for ."

And so she is reaching out to other sufferers and their carers in Seaham, just as she did after Louise was diagnosed, and she formed a Huntington's Easington district support group in Peterlee.

The disease is unpredictable in how it affects sufferers and as Cath says: "I have three members of my family with this and they are all affected differently."

Neither she nor David knew Huntington's was in the family when they wed and started a family.

They found out by accident after a bizarre incident involving David's brother Terry led to him being sectioned – and the examination revealed that he was suffering with Huntingdon's (see panel above).

An equally uncharacteristic incident involving David led him to be examined and it was discovered he too was suffering with the disease.

As David's condition deteriorated, there were times when Cath thought she was going to lose him, especially when his weight plummeted to eight stone. Swallowing is one of the problems for sufferers and Cath used to liquidise all his food.

Now he eats very little although he still enjoys the occasional glass of wine and is content, given the problems he has.

David has settled in the care home and he is looked after well. She sees him every day and they will be having a tea party to celebrate his 59th birthday next month.

But things were not so settled three years ago. In the space of three months there were three deaths of family and friends with Huntington's, and then Cath's brother died suddenly at 52. It all took its toll and she ended up having a breakdown, physically and mentally.

Cath fought back and today is doing her utmost to raise awareness and funds for research.

There is hope on the horizon that a drug currently used for chronic acne could delay the gene progression. The current trials are to work out the dosage.

Cath says: "Depending on the results, which at present look good, it could open doors for the future into finding a cure, which is what keeps me going – the thought of a cure for the girls."

Cath can be contacted on 07846804466 email david.odonnell@homecall.co.uk.

* Huntington's Disease Association tel: 0151 2983298 www.hda.org.uk dee boyd regional advsor for Huntington's Disease tel 0191 3731709 dee-boyd@hda.org.uk

* On July 4 the Northern branches of the Association are holding a fun day at Walkergate Hospital, Newcastle, from 1pm-4pm. There's fun and games for the children, aromatherapy treatments and guest speakers, including Dr Singh, a neuro psychiatrist from Northern Genetics at the Centre for Life. Anyone wishing to go should contact Linda Hunter on 07944 681512.