VANCOUVER, Wash. - Isaac Jensen looks like a normal, young school-age boy. He plays with blocks, reads books and is extremely well-spoken.

But when Isaac plays with his multi-colored blocks, and other people come into the room, he doesn't know it, or has little recognition. His unwavering focus is on the blocks, and nothing else.

When Isaac was 2 years old, he taught himself to read. But he didn't learn how to deal with social situations. Now, years later, he still has to learn to cope socially, and he has to learn it over and over again.

His fits of anger due to an inability to cope socially are a problem.

Isaac has Asperger's disorder, a mild form of autism, the mental condition that causes some children to live withdrawn, solitary lives, sometimes requiring care for their whole lives.

But Isaac's disorder is a "high-functioning" form of autism, and is also known as a Pervasive Development Disorder, or PDD. He appears close to being normal, but is still different from normal children, especially in social settings.

Undiagnosed children in mainstream schools also often face teasing, bullying and being labeled geeks or retarded, when in fact they may have elevated intelligence and talents in specific areas.

Asperger's and PDD are a challenge for medical professionals to diagnose. Another boy, 10-year-old Kenny, suffered at school due to a lack of clarity surrounding his condition. He was even given medication.

His mother and doctors tried for years to determine why he was suffering.

'He didn't have as much support," his mother says, "he just needs a little bit of support to get through and they didn't know exactly where to put him and what to do with him. He got a lot of "pull out," but he was still in mainstream [school], and he would go through his day and that would be it."

Isaac's mother, Audra Jensen, is a teacher at a school in Vancouver and is a specialist in early identification of children with Asperger's or PDD. She is Kenny's teacher as well.

The school district where Jensen teaches has a special program for children with PDD, but her work with her son Isaac goes on full-time. He has to be taught how to handle social situations over and over again.

Jensen has even written a book about the condition, called "When Babies Read," inspired by Isaac's feat.

"We're going to have to teach him what's appropriate, what's not appropriate- stuff that most kids just learn naturally," Jensen says. "And so while he is very high functioning and I believe will go on to lead a very independent life and be happy, he will need some special supports throughout his life."

The Centers for Disease Control and Prevention (CDC) has recently expanded the scope and definition of autism to include Asperger's and PDD. As a result, it is now estimated that one in 150 children in the United States are born with some form of autism.