Scientists have developed a molecular “clock” that could reshape how paediatricians measure and monitor childhood growth and potentially allow for an earlier diagnosis of life-altering development disorders.
The research, published this week in PNAS, (Full Study) describes how the addition of chemical tags to DNA over time can potentially be used to screen for developmental differences and health problems in children.
The study was led by researchers at BC Children’s Hospital, the University of British Columbia (UBC) and the University of California, Los Angeles. It is the first study to describe a method specifically designed for children, called the Paediatric-Buccal-Epigenetic (PedBE) clock, which measures chemical changes to determine the biological age of a child’s DNA.
Small chemical changes to DNA, known as epigenetic changes, alter how genes are expressed in certain tissues and cells. Some of these changes happen as a person ages and others may be in response to a person’s environment or life experiences.
In adults, these patterns of epigenetic changes are well established. They can be used to accurately predict a person’s age from a DNA sample or, if a person’s epigenetic age differs from their actual age, it can point differences in health, including age-related diseases and early mortality.
“We have a good idea how these DNA changes occur in adults, but until now we didn’t have a tool that was specific for children,” says Dr. Michael Kobor, senior author of study. “These DNA changes occur at very different rates in kids and so we adapted this technique for younger ages.”
Kobor is an investigator at BC Children’s Hospital and the Centre for Molecular Medicine and Therapeutics, a professor in the Department of Medical Genetics at the University of British Columbia, the Tier 1 Canada Research Chair in Social Epigenetics and the Sunny Hill BC Leadership Chair in Child Development.
The PedBE clock was developed using DNA methylation profiles from 1,032 healthy children whose ages ranged from a few weeks old to 20 years. The researchers found 94 different sites in the genome that, when tested together, could accurately predict a child’s age to within about four months. The team also found that children who spent longer in the womb showed an accelerated rate of DNA change by three months, demonstrating that this tool could be used to indicate an infant’s developmental stage. The analysis can be done cheaply and efficiently on cells collected from a cheek swab.