There has been a long-standing debate in the scientific community surrounding the importance of “junk DNA.” Junk DNA refers to the sections of DNA that are noncoding or are not involved in making the proteins our cells need to function. As more research has been conducted on junk DNA, scientists are discovering that these noncoding sequences are not just “junk” after all. A recent study from Princeton University in collaboration with the Howard Hughes Medical Institute found underlying causes of autism associated with mutations in junk DNA.
The research team conducted their study by analyzing the genomes of 1,790 individuals diagnosed with autism whose parents and other siblings were completely unaffected. The lack of a family history of autism supports the idea that these individuals developed autism through the introduction of new mutations, not inherited ones. The results of the genome analysis revealed that the individuals did, in fact, have mutations located in noncoding regions of DNA. These mutations were found to disrupt transcriptional regulation domains, which are involved in initiating the transcription of genes. Transcription is the process of taking a gene encoded in DNA and making an RNA product that can later be made into a protein by translation. The mutations were also linked to the post-transcriptional regulation of genes as well. These various regulations were found to influence gene expression in the brain, especially with genes that have been previously linked to autism. The most common genes that these mutations were associated with were those involved with neuronal migration, the movement of neurons to their final place in the brain, and development in the brain.
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The researchers wanted to confirm if the results of the genome scan and the mutations they found had any influence on a living model. The team inserted these high-impact mutations they found into cultured cells in order to investigate their impact on gene expression. The results from this experiment mirrored the patterns of regulation in both transcriptional and translational modifications that were found from the genome analysis. These results strongly suggest that there is a link between mutations in noncoding DNA and the onset of changes in gene expression that can lead to the development of autism. The research team is planning on conducting further experiments to determine how these mutations are influencing autism to better explain this new-found relationship.
This study adds to previous ones in looking into the role that noncoding or “junk” DNA has on regulating gene expression. Further research and use of genetic screens in the future could apply this concept to other diseases, hopefully leading to a more comprehensive understanding of the various influences that can lead to the onset of disease.
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