AFTER 18 years, the answer arrived in an innocuous brown envelope.
Helen Harkins opened the letter expecting to see details of a hospital appointment.

Instead there was a paragraph of text saying the very latest genetic research had diagnosed her son Lewis.

Mrs Harkins says: “I had to read it and read it and read it. It was just totally out of the blue.

“I photographed it and I sent the pictures to my husband Brian and he phoned and it was very emotional.”

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 “We could hardly talk,” her husband, Brian Harkins, recalls. “We were very choked up.”

They quickly turned to the internet to find out more about what the letter described as “a mutation in a gene called KCNQ2”. 

For the first time since Lewis was born, they could research his condition.

However, there was not a wealth of information. KCNQ2 is involved in the proper operation of potassium channels in the brain and mutations are a rare and recently identified problem. 

One website would later tell them just 257 children had been diagnosed with the disorder in the world, and just seven in the UK. 

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Nevertheless Mrs Harkins, 44, felt an overwhelming sense of relief. “It put closure on so many things,” she says. “Why did it happen? How did it happen? It would have made such a difference to our lives if we had known that earlier.”

The couple, from Inverkip, near Greenock, knew something was wrong when Lewis was just three days old. He suffered a seizure in the maternity hospital, his eyes fixed, his body rigid. He spent the next three weeks in a special care baby unit and received medication through a syringe to control the seizures. Back home, aged four months, he was weaned off the drugs and the seizures never recurred. But as doctors monitored his development Lewis, the Harkins’s first child, did not tick off typical infant milestones. His muscle tone was floppy, he could not speak, he did not walk until he was five years old.

“It was horrible,” says Mrs Harkins, a nurse. “It was upsetting and it was very frustrating because you wanted an answer and no-one was able to give you an answer,” says Mrs Harkins, a nurse. 

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The couple waited until Lewis was seven before they decided to expand their family, unsure if the condition could recur. But not wanting fear to rule their lives, they had Blair, now 11, and Rebecca, nine, who were both perfectly healthy.

Today these younger siblings talk about throwing balls for Lewis to catch and squeeze, and point out where a trampoline is to be inserted in the decking for their big brother.

Inside Lewis grins broadly, claps his hands and springs lightly up and down on the sofa. He is relaxed and happy in a home flowing freely with family and friends. He is also enjoying the cream couch, given he is usually directed to the firmer brown one bought to withstand his inclination for bouncing.

But aged 18, Lewis cannot talk. If he is in pain, his parents say he cries and bites his hand but cannot point to suggest what is wrong.

Over the years they have investigated many possibilities to explain and improve Lewis’s condition. They regularly visit a specialist centre for brain-injured children in England. Lewis has undergone oxygen therapy and been to Florida to swim with dolphins – each adventure making small differences.

He has begun to make more eye contact and now loves social gatherings.

Mr Harkins, 42, says at the beginning one consultant told them to stop wasting their money and to accept their situation.

They ignored him. When Lewis was five they paid to see a private paediatrician who led them to seek genetic testing to identify his condition.

Routine blood tests revealed nothing, leaving the family only with speculation – it might be cerebral palsy, it might be autism.

Then in 2011 they received a letter inviting Lewis to participate in a Deciphering Developmental Disorders study. They posted off a swab taken from inside Lewis’s mouth and that is what, five years on, led to the surprise letter from the Department of Clinical Genetics at Glasgow’s new Queen Elizabeth University Hospital.

Within days they were talking on the phone to a father in Dublin whose toddler has the same KCNQ2 mutation.

Mr Harkins, a financial adviser, says: “All of a sudden we were talking to someone who knew exactly what we were going through, but he was even more delighted because of Lewis’s age. Because of his kid’s complications he was thinking about the possibility of short life expectancy.”

Knowing what has affected Lewis has given the Harkins family hope – treatments are being researched in America – and while they recognise genetic testing can be an arduous process that is not readily available on the NHS, they want other families to know the possibilities it might offer for them.

Mrs Harkins says: “We know a lot of children that are like Lewis and have never had a diagnosis so you can bet that there will be children with the same problem. I would like people to know that they could get a diagnosis.

It might not be that the child has this gene, but it is another route for them to explore.”