The dark genome may sound like something out of science fiction. However, it’s actually present in every human being. And it may hold vital information about genetics that could lead to more accurate diagnoses and better treatments for complex mental health illness. Mental health disorders such as autism spectrum disorder, bipolar disorder, posttraumatic stress disorder (PTSD), and schizophrenia, may all benefit from new knowledge about the dark genome.
What Is the Dark Genome?
In 1990, the Human Genome Project launched with the audacious goal of sequencing all DNA in the human body. Thirteen years later and two years ahead of schedule, the project’s leaders announced that they had succeeded.
Scientists view this project as one of the most significant scientific achievements in human history. But it has not, as some believe, resulted in a complete understanding of the entire human genome:
- The Human Genome Project led to the mapping of more than 20,000 genes that are responsible for coding proteins.
- However, these genes only account for about 2% of the human genome.
- The remaining 98% of genomic space contains information we don’t understand – yet.
- This area has become known as the dark genome.
In the decades since The Human Genome Project completed its work, advances in genetic science have helped researchers develop greater insights into the possible functions and responsibilities of the dark genome.
As reported by David Cox in an April 2023 BBC Future article, experts now believe that the dark genome influences how genes respond to environmental factors such as stress, pollution, diet, and exercise. One new revelation is the connection between genetics and complex mental illness.
“[Humans are] master adapters to the environment at every level. And that adaptation is the information processing,” molecular biologist Samir Ounzain said in Cox’s article. “When you go back to the question of what makes us different to a fly or a worm, we’ve increasingly realized that the answers lie in the dark genome.”
The Dark Genome, Bipolar Disorder, & Schizophrenia
In December 2021, a team of researchers from the University of Cambridge published a study in the journal Molecular Psychiatry that linked areas of the dark genome with bipolar disorder and schizophrenia. This is one of the first studies that explored the relationship of this component of genetics and complex mental illness.
“When we look outside the regions of DNA classed as genes, we see that the entire human genome has the ability to make proteins, not just the genes,” the study’s lead author, Chaitanya Erady, said in an article on the university’s website. “We found new proteins involved in biological processes and are dysfunctional in disorders like schizophrenia and bipolar disorder.”
The researchers believe that the areas of the dark genome that they identified formed during the period of human evolution that involved the development of greater cognitive abilities. Since these areas developed rapidly (in evolutionary terms), they may be more prone to disruption than other areas are. The impact of these disruptions, the researchers believe, may include bipolar disorder and schizophrenia.
In addition to providing greater insights into why some people develop bipolar disorder and schizophrenia, this research may also lead to new ways of treating — or perhaps even someday preventing – these disorders.
“This opens up huge potential for new druggable targets,” research team member Sudhakaran Prabakaran said in the University of Cambridge article. “It’s really exciting because nobody has ever looked beyond the genes for clues to understanding and treating these conditions before.”
The Dark Genome & Other Mental Illnesses
In January 2023 – a little over a year after the publication of the University of Cambridge Study – the International Journal of Molecular Medicine published a review of research into the dark genome’s relationship to stress and several mental health disorders. This was another step toward defining the connection between this component of genetics and complex mental illness.
This review linked non-coding RNA molecules (or ncRNAs) to several stress-related mental health concerns, including:
- Anxiety disorders
- Bipolar disorder
- Depressive disorders
The review also noted that a special type of ncRNA, which is known as long ncRNA (or lncRNA), appears to regulate genes that are involved in mental illnesses such as:
- Autism spectrum disorder
- Major depressive disorder
- Posttraumatic stress disorder (PTSD)
- Schizophrenia
“ncRNA molecules are able to orchestrate the expression of genetic information in the most complex, rapid and reversible manner, participating in almost every major biological process,” the review team wrote. “A prime example of such a process is the maintenance of homeostasis, the internal physiological balance, despite internal and external stressful stimuli.”
When the parts of the dark genome that are responsible for maintaining that physiological balance are disrupted or otherwise prevented from functioning properly, the result may be the various mental illnesses that are mentioned in this section.
What Does This All Mean?
It has now been more than three decades since The Human Genome Project was announced, and about 20 years since the initial sequencing of 20,000 genes was completed.
In the immediate aftermath of the end of the Human Genome Project, many experts believed that the dark genome was filled with little more than what they described as “junk DNA,” or scraps of irrelevant and apparently useless information.
Through the years – as indicated by the studies mentioned in this post — researchers have made tremendous progress in the effort to explore and understand the dark genome. Yet, in many respects, research in this area is still in its infancy.
The vast majority of the dark genome remains unexplored and shrouded in mystery. The areas that have been analyzed show great potential for advances in how mental health disorders and other conditions are diagnosed and treated. But the key word in the previous sentence is this one:
Potential.
It is highly unlikely that the current research will yield new medications or treatment techniques in the immediate future. What it will do, though, is increase experts’ understanding of the complex factors that contribute to mental illnesses. It will also provide a foundation for future studies that may one day lead to breakthrough treatments.
One immediate benefit of this research is that it provides another tool with which to reduce stigma and counter sadly persistent misinformation about the nature of mental illnesses.
Too many people cling to the outdated belief that mental health concerns are evidence of poor character, insufficient self-control, or other personal flaws. Every advance in genetic research further solidifies our understanding of mental illnesses as legitimate and treatable health concerns.
And every time someone accepts this truth, that brings us another step closer to the day when stigma and fear will no longer prevent anyone from seeking the professional care that can significantly improve their lives.
Gianna Melendez
Jodie Dahl, CpHT