Now seven, Chanochi Pearl was diagnosed with Familial Dysautonomia (FD) at five months.

He cannot swallow and for 18 hours a day is attached to a feeding bottle which pumps in essential nutrients at the family's Edgware home.

His father Ian, a 49-year-old solicitor, explained: "FD affects the sensory and autonomic nervous system. The bits you and I don't think about doing don't work for him.

"His eyes don't produce natural tears. He has blood pressure problems and has developed scoliosis. And that is just an idea of what he has had to deal with."

Mr Pearl and his wife Jane, 43, a trained nurse and midwife, knew something was wrong when Chanochi - born by emergency Caesarean six weeks prematurely - wouldn't feed. But it was when they found him not breathing one evening that panic kicked in.

We want to raise awareness of screening

"I had to call an ambulance and we had to resuscitate him," Mr Pearl said. "We were sent home afterwards.

"It happened three times in a row just at home. It is a miracle he is still here."

It was after the third occasion that Chanochi was admitted to hospital and doctors carried out tests to get to the root of his problems.

"A friend told us about a relative's child born with similar symptoms who had been diagnosed as FD. It was the first time we'd ever heard of the condition."

His wife added that although there was general awareness of Tay-Sachs, few people knew about FD.

"We were devastated," Mr Pearl recalled. "When you get any diagnosis like that, you think you will never have a happy day in your life ever again."

Despite requiring a team of doctors and therapists to manage and support him with round-the-clock care, Chanochi is "such a character", his father said.

"But the point we want to raise is it was all avoidable. When my wife was screened for Tay-Sachs, if there had been a box that said: 'Do you want to be screened for other conditions?' we would have said 'yes'."

Mr Pearl - who became a trustee of Jnetics to help raise awareness of the issue - spoke of the couple's frustration at hearing people say "the community shouldn't test for it because wider society would think of us a damaged race, which is just untrue.

"That is why we want to raise awareness of screening. Life is hard when you have a child with FD but we get on with it and we try not to let it define our lives."

Mrs Pearl said it was not clear what the future holds for their son.

"When he was diagnosed, the statistics stated that half of the people diagnosed with FD live to their 30th birthday. Now with some advances in medical management, we hope it will be much longer.

"Ian worries a lot about the future and who will look after Chanochi when we are no longer around. I tend to live more in the present and not think too much about the future. Parents who have a child with FD can expect a rollercoaster ride. Life is tough as you are dealing with a very sick child, whilst at the same time trying to look after other family members and hold down a job.

"The lows can be very low but on the flip side, the highs are wonderful. You have to learn to enjoy the moment, live in the present and appreciate the small but important things in life."