Autism: A Chromosomal Disorder?

New research points to the direction of the regions of 4 chromosomes that appear to be linked with development of autism. Researchers screened the DNA of more than 150 pairs of siblings with autism. They found extremely strong evidence that two regions on chromosomes 2 and 7 contain genes that are involved with autism. Likely locations for autism-related genes were also found on chromosomes 16 and 17, although the strength of the correlation was somewhat weaker. The findings appear in the September issue of the American Journal of Human Genetics.

The researchers were definite about Chromosome 7 and 4 as being associated with autism. Chromosome 7 is known to be associated with many language disorders and to autism in some earlier studies. They were also interested in the evidence of a link on chromosome 2, and the interaction between the genes for early brain development located on chromosome 2 and environmental influences.

At least 1 in 500 people is affected by some form of autism, a neurodevelopmental disorder that causes problems with communication and social interaction, as well as repetitive actions and interests. Earlier studies with families and twins have shown that there is likely to be a strong inherited component to autism. Because of the wide range of patients' symptoms, many researchers suspect the disorder is the result of a complex interaction between several different genes involved with brain signaling and development. Unidentified environmental factors are also likely to play a role.

The researchers feel that large numbers, like 400-500 pairs of relatives, are needed to get more definitive answers. This work was carried out by members of the International Molecular Genetic Study of Autism Consortium, a group of clinicians and scientists from the United States, United Kingdom, France, the Netherlands, Denmark, Italy, and Greece.