December 13, 2012
Study Links Fragile X Syndrome To 93 Different Autism Genes
Connie K. Ho for redOrbit.com — Your Universe Online
Researchers from Duke University Medical Center and Rockefeller University recently discovered that the gene responsible for fragile X syndrome is connected to almost 100 other genes that have been linked to autism. While researchers have long been aware of a relationship between fragile X syndrome and autism, this is the first time that they have begun to trace out the exact genetic pathways that link the two disorders together.
In the past, fragile X syndrome has been considered an inherited intellectual disability and has often been linked to autism. According to the Duke University Medical Center, about two to six percent of children with autism are diagnosed with fragile X. Additionally, about one-third of fragile X patients also meet the standards for autism.
Fragile X syndrome is caused by defects in a small portion of the gene that codes for the fragile X mental retardation protein (FMRP). FMRP is responsible for regulating the production of other proteins in the brain and other organs by searching for specific genetic patterns during the process of genetic translation, during which genetic code is translated into the amino acids that make up proteins. Once the FRMP discovers these genetic messages, it attaches to them and is thereby able to control where and when the protein is created.
However, with fragile X syndrome, this process does not function correctly due to a defect in the gene that makes the body produce none or too little FMRP. The FMRP is then unable to correctly regulate the proteins and the proteins may be produced in the wrong place and at the wrong the time.
Although autism has been linked to the fragile X syndrome, scientists have previously been unable come up with a clear explanation as to how the two are related. The new study works to resolve this issue by promoting genetic testing as a way to diagnose and organize the different autism-related disorders. The team of investigators utilized a mix of laboratory experiments and advanced bioinformatics to determine the genetic messages that FMRP searches for.
"We can now look for changes in the FMRP binding sites of genes to identify potential new genetic links to autism-spectrum disorders," explained Neelanjan Mukherjee, a post-doctoral researcher at Duke University who assisted with the research, in a statement.
Through the project, the researchers discovered that FMRP has direct control over 93 genes, each of which is independently connected to autism and other similar neurological syndromes. Furthermore, using a mouse model of the fragile X syndrome, they found that abnormal protein production can occur in the ovary as well as the brain. The absence of the FMRP protein leads to ovarian insufficiency, a condition commonly found in women with fragile X syndrome.
"We now know not only which genes are linked to FMRP, but we can locate exactly where they interact," explained Uwe Ohler, associate professor of Biostatics and Bioinformatics at the Duke Institute for Genome Sciences & Policy. "Down the road, this finding could lead to more detailed genetic tests that take into account the subtle ways that genes get turned on and off."
With the findings, the researchers believe that they will be able to better explore the various molecular pathways that are related to the different types of autism. By identifying these pathways, the scientists will also be able to develop more targeted treatments of autism and fragile X, as many fragile X patients have unique challenges.