Blog | Monday, October 31, 2011

QD: News Every Day--Human brains consistent despite other racial differences

Human brains have a consistent molecular architecture despite all the other genetic differences across individuals and ethnicities, according to two studies that recorded when and where genes turn on and off in multiple brain regions throughout life.

Source: JNenad Sestan, MD, PhD, Yale University Department of Neurobiology and Kavli Institute for Neuroscience, via NIHDespite individual and ethnic genetic diversity, the human prefrontal cortex shows a consistent molecular architecture, as shown in this picture. The vertical span of color-coded areas is about the same, indicating that our brains all share the same tissue at a molecular level, despite distinct DNA differences on the horizontal axis. Each dot represents a comparison between two individuals.

The research appeared in the Journal Nature and was described by the National Institutes of Health in a press release.

The first study focused on how genetic variations are linked to the expression of transcripts in the brain's prefrontal cortex, the area that controls insight, planning and judgment, across the lifespan. They studied 269 postmortem, healthy human brains, ranging in age from two weeks after conception to 80 years old, using 49,000 genetic probes.

This information about when and where specific genes are expressed in the brain from pre-natal stages to the end of life brings new hope for understanding how this process can go awry in schizophrenia, autism and other brain disorders.

A second study concluded that men show more sex-biased gene expression, especially prenatally. Some genes found to have such sex-biased expression had previously been associated with disorders that affect men more than women, such as schizophrenia, Williams syndrome and autism.

The researchers characterized gene expression in 16 brain regions, including 11 areas of the neocortex, from both hemispheres of 57 human brains that spanned from 40 days post-conception to 82 years, analyzing the transcriptomes of 1,340 samples.

Among key findings from this second study, they concluded that more than 90% of the genes expressed in the brain are differentially regulated across brain regions and/or over developmental time periods. Sex differences in the risk for certain mental disorders may be traceable to transcriptional mechanisms. More than three-fourths of 159 genes expressed differentially between the sexes were male-biased, most prenatally.