Renata O'Sullivan lives with husband, Nigel, and five-year-old son, Callum, in Church Village, near Abercynon in Wales. Last year they sent their eldest son, Sean to America to attend the controversial Higashi School for autistic children in Boston.

Sean was my first child, born at the end of March 1989. He was a brilliant boy - and handsome, with blonde hair, blue eyes and a little dimple. A lot of families say there was something wrong with their child from the start, but Sean was absolutely normal.

On his second birthday he fell ill. I was working full time then, so at first I didn't really notice any problems. He was increasingly frustrated, biting anything. Eventually he became completely withdrawn, never engaging in eye contact.

I didn't know what to make of it so I took him to my GP, who said it was a phase.

It was three years before he was diagnosed as autistic. In the end, I took him to Great Ormond Street Hospital. I remember the day so clearly. I wanted him to make a good impression so I got some new clothes, a little continental outfit. I thought if he looked gorgeous they would think there was nothing wrong, quite pathetic really.

Our whole world fell apart when they said he was autistic and that it had been brought on by viral encephalitis when he was two. If he had been born with it I would have been able to accept it. But it was like having two different children, a beautiful, well-behaved toddler and a naughty boy.

At home he was terrible, wrecking everything, biting everything, emptying things on to the floor. He had a thing about ice and would be in and out of our freezer. Once he burnt his tongue by getting it stuck on the ice.

I thought a good school would calm him down and teach him things. So the local authority suggested he go to a special unit for autistic children at a nearby primary school. But they couldn't cope with him, either.

We were getting really desperate when, by chance, I heard about the Higashi School. We got the application form and visited the school almost straight away. As soon as I got there I had a good feeling about the place. All the children were really happy, they walked around in perfect lines just grinning.

It was touch-and-go whether he was going to get a place, because they usually take children at three years old and he was seven at the time. When he got accepted, we remortgaged the house and started raising the pounds 57,500 needed for the fee and residential costs.

He has only been there a year now, but the change in his behaviour is remarkable. He doesn't need nappies any more, he doesn't have tantrums and he doesn't bite everything he sees. He even sleeps through the night on his own.

But the thing that made me choke was seeing him enunciate sounds. He said "oooh" and "aaah" really clearly. Before, everything was just a vague burble.

I was worried that he would lapse into his old ways when he came back over the summer, but he didn't. We even had a family outing that I actually enjoyed. Sean queued for a ride along with all the other children and didn't have a tantrum. I was so proud of him.

It is the first time in years that we are enjoying being with Sean. I don't want him to be residential for ever, but I think he should stay at the school for another few years. In the end, though, I want him home with me. I want to be able to cope.