By CLAUDIA WALLIS

Published: November 2, 2009

It is one of the most intriguing labels in psychiatry. Children with Asperger’s syndrome, a mild form of autism, are socially awkward and often physically clumsy, but many are verbal prodigies, speaking in complex sentences at early ages, reading newspapers fluently by age 5 or 6 and acquiring expertise in some preferred topic — stegosaurs, clipper ships, Interstate highways — that will astonish adults and bore their playmates to tears.

In recent years, this once obscure diagnosis, given to more than four times as many boys as girls, has become increasingly common.

Much of the growing prevalence of autism, which now affects about 1 percent of American children, according to federal data, can be attributed to Asperger’s and other mild forms of the disorder. And Asperger’s has exploded into popular culture through books and films depicting it as the realm of brilliant nerds and savantlike geniuses.