Washington: The "switching on" or expression of specific genes in the human genome is what makes each human tissue and each human being unique. Now a study has found many gene expression changes that occur during foetal development, are reversed immediately after birth.
A team from the Johns Hopkins Bloomberg School of Public Health, the Lieber Institute for Brain Development, and the National Institute of Mental Health also found that the gene
expression change is fastest in human brain tissue during foetal development.
The gene expression change slows down through childhood and adolescence, stabilises in adulthood, and then speeds up again after age 50, with distinct redirection of expression changes prior to birth and in early adulthood.
Using a number of genomic analysis technologies, the team conducted genome-wide genetic (DNA) and gene expression (RNA) analyses of brain tissue samples from the prefrontal cortex.

Tissue represented the various stages of the human lifespan.
"We think that these coordinated changes in gene expression connecting foetal development with ageing and neurodegeneration are central to how the genome constructs the human brain and how the brain ages," said Carlo Colantuoni, who led the team.
The research also showed that brain gene expression differences between genetically diverse individuals are no greater than the differences between individuals sharing many
more genetic traits.
"Our findings highlight the fact that current technologies and analysis methods can address the effects of individual genetic traits in isolation, but we have virtually no understanding of how our many millions of genetic traits work in concert with one another," Colantuoni said.