Researchers have found a new genetic cause of autism that appears to cause a severe type seen in girls. The genetic cause appears to be a rare single gene mutation that hampers the normal development of the brain.
The gene is called CTNND2 and it provides instructions in the cell for making a protein called delta-catenin, which plays several crucial roles in the nervous system. The multi-center research team studied a group of 13 girls with severe autism and found they carried mutations in the CTNND2 gene that reduced the effectiveness of delta-catenin. Because of delta-catenin's several roles, this single mutation may affect many areas of brain development. Delta-catenin is believed to help guide nerve cells to their proper place during their formation as the brain develops.
The genes of the girls with autism were compared to genes carried by people who did not have autism. The researchers discovered three other potential genes for autism in addition to CTNND2.
CTNND2 has been linked to another serious developmental disorder called cri-du-chat syndrome, which causes profound developmental problems. People with cri-du-chat lack a CTNND2 gene in each cell.
This finding is part of a strategy in autism research. Researchers are focusing on rare and severe types of autism. By looking for genes that have a more powerful effect on brain development, they hope to find an explanation for the root causes of autism. Girls are less likely to have autism than are boys. When girls do develop autism, it tends to be more severe than in boys. Because of this, any genetic cause for autism in girls is likely to be more important and may have an earlier and more significant impact for anyone with autism.
The study was published in the journal Nature and was funded by the organization Autism Speaks.