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Archive - Mar 22, 2019

Western Bias in Human Genetic Studies Is “Both Scientifically Damaging and Unfair”—Prominent Geneticists Call for Concerted Effort to Increase Diversity in Human Genomic Studies

Despite efforts to include more diversity in research, people of European ancestry continue to be vastly overrepresented and ethnically diverse populations largely excluded from human genomics research, according to the authors of a commentary published on March 21, 2019, in a special issue of Cell on human genetics. This lack of diversity in studies has serious consequences for science and medicine. For one thing, the authors say, the bias in the data limits scientists' understanding of the genetic and environmental factors influencing health and disease. It also limits the ability to make accurate predictions of a person's disease risk based on genetics and to develop new and potentially more effective treatment approaches. "Leaving entire populations out of human genetic studies is both scientifically damaging and unfair," says co-author Sarah Tishkoff (@SarahTishkoff), PhD, Professor, Departments of Genetics & Biology, Perelman School of Medicine, University of Pennsylvania. "We may be missing genetic variants that play an important role in health and disease across ethnically diverse populations, which may have deleterious consequences in terms of disease prevention and treatment." Dr. Tishkoff and her colleagues, including Giorgio Sirugo, MD, PhD, Senior Research Investigator, University of Pennsylvania, and Scott M. Williams, PhD, Professor, Director, Epidemiology & Biostatistics Graduate Studies Program, Case Western Reserve University School of Medicine, report that, as of 2018, individuals included in genome-wide association studies (GWAS) were 78% European, 10% Asian, 2% African, 1% Hispanic, and <1% all other ethnic groups. GWAS studies search the genome for small variations that occur more frequently in people with a particular disease or other trait than in people without the disease or trait.

Major Depressive Disorder: Neurons from SSRI Non-Responders Have Longer Neuron Projections Than Responders; Gene Analysis Reveals That SSRI Non-Responders Also Have Low Levels of Protocadherin Genes (PCDHA6 & PCDHA8) Involved in Forming Neuronal Circuits

Selective serotonin reuptake inhibitors (SSRIs) are the most commonly prescribed medication for major depressive disorder (MDD), yet scientists still do not understand why the treatment does not work in nearly thirty percent of patients with MDD. Now, Salk Institute researchers have discovered differences in growth patterns of neurons of SSRI-resistant patients. The work, published in Molecular Psychiatry on March 22, 2019, has implications for depression as well as other psychiatric conditions such as bipolar disorder and schizophrenia that likely also involve abnormalities of the serotonin system in the brain. "With each new study, we move closer to a fuller understanding of the complex neural circuitry underlying neuropsychiatric diseases, including major depression," says Salk Professor Fred “Rusty” Gage (https://www.salk.edu/about/management-team/), PhD, President of the Salk Institute, Professor-Laboratory of Genetics, and the Vi and John Adler Chair for Research on Age-Related Neurodegenerative Disease, and the study's senior author. “This paper, along with another we recently published (January 30, 2019 in Molecular Psychiatry), not only provides insights into this common treatment, but also suggests that other drugs, such as serotonergic antagonists, could be additional options for some patients." The title of the new article is “Altered Serotonergic Circuitry in SSRI-Resistant Major Depressive Disorder Patient-Derived Neurons” (https://www.nature.com/articles/s41380-019-0377-5). The earlier paper is titled “Serotonin-Induced Hyperactivity in SSRI-Resistant Major Depressive Disorder Patient-Derived Neurons” (https://www.nature.com/articles/s41380-019-0363-y).

Chronic Pain--Scientists Close in on Origins; New Human Study ID’s Top 10 Genes for Future Focus—All 10 Are Involved in Immune Signaling & Response; Expression of These Genes “Strikingly” Different in Males vs Females; Results "Should Have Broad Impact"

A new study by researchers at The University of Texas (UT) at Dallas, UT MD Anderson Cancer Center, UT Health Science Center at Houston, and Baylor College of Medicine has produced evidence of the source of chronic pain in humans, revealing several new targets for pain treatment. The research reported in the paper--published online on March 19, 2019 in Brain, one of the world's oldest neurology journals--examined specialized nerve cells clustered near the base of the spine. The open-access article is titled “Electrophysiological and Transcriptomic Correlates of Neuropathic Pain in Human Dorsal Root Ganglion Neurons.” Researchers took advantage of an exceedingly rare opportunity to study these nerves, called dorsal root ganglia (DRG), removed from cancer patients undergoing surgery at MD Anderson. The researchers catalogued variations in RNA expression in the dorsal root ganglia cells of patients differing by pain state and sex. Using RNA sequencing, a specialized form of gene sequencing, on those DRG cells yielded a list of promising biochemical pathways for which researchers might be able to devise analgesic (pain-relieving) drugs. "This surgery is not done at many places," said Dr. Ted Price, PhD, a senior author of the paper and Eugene McDermott Professor of Neuroscience in the UT Dallas School of Behavioral and Brain Sciences. "Our patient cohort of 21, though it doesn't sound like many, is huge, relative to any prior human chronic pain study using RNA sequencing." Chronic pain is labeled as neuropathic when it is caused by damage to nerve cells. Examples include phantom limb syndrome, pain resulting from a stroke, and the "pins and needles" sensations associated with diabetes.