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Autism was first described in 1943 by Johns Hopkins psychiatrist Leo Kanner, and again in 1944 by Austrian pediatrician Hans Asperger. Kanner applied the term to children who were socially withdrawn and preoccupied with routine, who struggled to acquire spoken language yet often possessed intellectual gifts that ruled out a diagnosis of mental retardation. Asperger applied the term to children who were socially maladroit, developed bizarre obsessions and yet were highly verbal and seemingly quite bright. There was a striking tendency, Asperger noted, for the disorder to run in families, sometimes passing directly from father to son. Clues that genes might be central to autism appeared in Kanner's work as well.
But then autism research took a badly wrong turn. Asperger's keen insights languished in Europe's postwar turmoil, and Kanner's were overrun by the Freudian juggernaut. Children were not born autistic, experts insisted, but became that way because their parents, especially mothers, were cold and unnurturing.
In 1981, however, British psychiatrist Dr. Lorna Wing published an influential paper that revived interest in Asperger's work. The disorder Asperger identified, Wing observed, appeared in many ways to be a variant of Kanner's autism, so that the commonalities seemed as important as the differences. As a result, researchers now believe that Asperger and Kanner were describing two faces of a highly complicated and variable disorder, one that has its source in the kaleidoscope of traits encoded in the human genome. Researchers also recognize that severe autism is not always accompanied by compensatory intellectual gifts and is, in fact, far likelier to be characterized by heartbreaking deficits and mental retardation.
Perhaps the most provocative finding scientists have made to date is that the components of autism, far more than autism itself, tend to run in families. Thus even though profoundly autistic people rarely have children, researchers often find that a close relative is affected by some aspect of the disorder. A sister may engage in odd repetitive behavior or be excessively shy; a brother may have difficulties with language or be socially inept to a noticeable degree. In similar fashion, if one identical twin has autism, there is a 60% chance that the other will too and a better than 75% chance that the twin without autism will exhibit one or more autistic traits.
How many genes contribute to susceptibility to autism? Present estimates run from as few as three to more than 20. Coming under intensifying scrutiny, as the papers published by Molecular Psychiatry indicate, are genes that regulate the action of three powerful neurotransmitters: glutamate, which is intimately involved in learning and memory, and serotonin and gamma-aminobutiric acid (GABA), which have been implicated in obsessive-compulsive behavior, anxiety and depression.