Researchers have discovered the presence of common groups of genes in individuals with schizophrenia, bipolar disorder, and major depression. If these genes are responsible for these mental illnesses, could gene editing methods like CRISPR-Cas9 could be a possible treatment option?
In many respects, the nature of mental illness remains a mystery to medical professionals, despite the progress made in diagnosis and treatment.
In addition to the role that life experiences and early childhood development may play, medicine has always suspected that there is some hereditary element to mental illness. More recent research, however, indicates that the individual genes might be responsible for certain mental illnesses more than previously thought.
“It was striking to us that we could identify the broad functional overlaps, knowing there is a lot of variability among individuals with mental disorders.” – Sarven Sabunciyan
Understanding and Diagnosing Mental Illness
Researchers at the Stanley Division of Developmental Neurovirology at the Johns Hopkins University School of Medicine used RNA sequencing methods to identify the genetic commonalities in the brains of deceased patients diagnosed with three different mental illnesses.
Tissues samples were taken from 157 defunct donors aged between 19 and 68 at the time of death. Ninety-three percent of donors were Caucasian, and 63 percent were male.
Thirty-five percent of those studied suffered from schizophrenia, while 33 percent suffered from bipolar disorder. Their genome was compared to that of a 32-person control group not diagnosed with or afflicted by mental disorders.
Scientists worked on over a hundred sample tissues from the hippocampus region of the brain and 57 samples from the orbitofrontal cortex. They extracted and sequenced the mRNA of the donors, which is the blueprint created by DNA for corresponding protein growth. Afterward, the researchers compared collected RNA sequences with a complete human genome.
The researchers noted that, in the samples from the patients diagnosed with mental illness, mRNA production was either higher or lower than levels seen in patients not suffering from mental illness. Therefore, if the mRNA production imbalance is responsible for these mental illnesses, mRNA production could theoretically be regulated via gene editing in order to treat the diseases.
“There are subtle differences in individual genes, and these differences are enriched in sets of genes involved in specific cell processes in the brain tissue of people with a variety of severe mental disorders,” explains Sarven Sabunciyan, Ph.D., one of the authors of the study.
Sabunciyan continued by adding that “it was striking to us that we could identify the broad functional overlaps, knowing there is a lot of variability among individuals with mental disorders.”
After identifying similarities among schizophrenic, bipolar and severely depressed patients on the genetic level, could it be possible to treat these mental illnesses on the genetic level?
Genome editing introduces a “working” version of a defective gene into the DNA of an individual, and CRISPR-Cas9 specifically allows the targeting, cutting and replacing of a specific gene.
The study and its findings not only help to deepen our understanding of the complexity of the human genome, but also has the potential to enable better diagnosis and treatment of certain mental disorders.