Researchers at Mount Sinai School of Medicine are first to strongly link a specific gene with autism. While earlier studies have found rare genetic mutations in single families, a study published in the April issue of the American Journal of Psychiatry is the first to identify a gene that increases susceptibility to autism in a broad population.
Approximately 1 in 1,000 people have autism or autistic disorder. It appears to be the most highly genetic of all psychiatric disorders. If a family with one autistic child has another child the chance that this child would be autistic is 50 to 100 times more likely to than would be expected by chance. However, it's clear that no single gene produces the disorder. Rather, the commonly accepted model states that it is a result of the accumulation of between five to ten genetic mutations.
"Identifying all or most of the genes involved will lead to new diagnostic tools and new approaches to treatment," said Joseph Buxbaum, PhD, Associate Professor of Psychiatry, Mount Sinai School of Medicine and lead author of the study.
Several studies have implicated a region on chromosome 2 as likely to be involved in autism. An earlier study by Dr. Buxbaum and his colleagues narrowed the target to a specific region on this chromosome. He and his colleagues conducted a systematic screening of this region in 411 families that have members with autism or autistic disorder. The families were recruited through The Seaver Autism Research Center at Mount Sinai School of Medicine and the Autism Genetic Resource Exchange.
They found genetic variations in one gene that occur with greater frequency in individuals with autism disease and their family members. This gene codes for a protein that is involved in production of ATP, the molecule that acts as fuel providing the energy cells need to function. The mutations identified lead to production of excessive amounts of this protein. Dysfunction of this gene could lead to irregularities in the production of molecules that fuel the cells. Since brain cells consume large amounts of energy even minor disruptions in production of such fuel can significantly affect the cells ability to function normally.
The abstract of the paper identifies the gene as Mitochondrial Aspartate/Glutamate Carrier SLC25A12.
Why don't we already know all the genes that contribute to autism? It costs too much to do genetic sequencing. If the cost of DNA sequencing was about 3 orders of magnitude lower then the entire genomes of tens of thousands of autistic and non-autistic people could be sequenced and we'd find out very quickly which genetic variations contribute to autism and to most other diseases as well.
Since the costs of DNA sequencing and of testing individual DNA letters (Single Nucleotide Polymorphisms or SNPs) continues to drop and since it is reasonable to expect the costs to drop by two or three orders of magnitude within the next 10 years I expect all the genetic variations that contribute to autism, Alzheimer's, Parkinson's and most other neurological diseases to be known by 2015. The rate of discovery of contributing genetic variations will rise by orders of magnitude as the costs drop by orders of magnitude.
|Share |||Randall Parker, 2004 April 01 02:35 PM Brain Genetics|