Researchers with McGill University have reportedly identified a genetic mutation linked to the development of mood disorders and obesity in humans. Carl Ernst, et al., “Highly Penetrant Alterations of a Critical Region Including BDNF in Human Psychopathology and Obesity,” Archives of General Psychiatry, October 2012. After screening more than 35,000 people referred for genetic testing and comparing the results with data from approximately 30,000 control subjects, scientists found five participants with a rare genomic deletion of brain-derived neurotrophic factor (BDNF), “a nervous system growth factor that plays a critical role in brain development.” These participants all exhibited obesity and “mild-moderate intellectual impairment” as well as a mood disorder.

“The consensus phenotype for individuals with a deletion in BDNF suggests that young children are hyperactive and have an intolerance to change. As subjects age, they likely develop more pronounced anxiety and mood disorders, exemplified by the 16-year-old and 21-year-old subjects with major depressive disorder and generalized anxiety disorder and by a 25-year-old woman with mood disturbances from a previous report,” concludes the study. “Deeper investigation of the regulation of BDNF and of the molecular actions of the transcribed product will be required to better understand how hemizygosity at this locus contributes to psychopathology.”

The study purportedly represents the first successful attempt to definitively link a gene mutation to mood disorders and obesity in humans. “Mood and anxiety can be seen like a house of cards. In this case, the walls of the house represent the myriad of biological interactions that maintain the structure,” the lead author was quoted as saying. “Studying these moving parts can be tricky, so teasing apart even a single event is important. Linking a deletion in BDNF conclusively to mood and anxiety really tells us that it is possible to dissect the biological pathways involved in determining how we feel and act.” See McGill University Press Release, October 10, 2012.