Most babies born in developed countries have Guthrie cards created as a matter of routine. A small sample of a newborn’s blood taken from a heel prick is spotted onto filter paper and used to screen for a number of serious diseases. The cards are then stored for a period of time that varies with local regulations or custom.
An individual’s epigenome – the chemical modifications such as methylation to their DNA that influence gene expression - is known to be altered both by conditions in the womb and in the presence of disease. The difficulty is sorting out cause and effect; whether the epigenome of a person with a disease is a cause of their condition, or a consequence of it.
This study demonstrated that the state of an individual’s epigenome at birth is preserved on Guthrie cards, and validated two methods for obtaining this information from the cards. It was also able to identify epigenetic variations between individuals at birth that appeared unlinked to their underlying genetic differences, and which remained unchanged three years later.
These findings suggest that Guthrie card archives could be a powerful resource for understanding epigenetic alterations accompanying disease, and for identifying specific instances of epigenetic variation at birth that are predictors of disease in later life.
Using existing archives of Guthrie cards to carry out epigenomic research would be much cheaper and less time-consuming than labour-intensive longitudinal studies, but could present some problems of its own. Variability in storage methods might affect the reliability of the epigenomic information the cards contain for example, and ethical or legal issues could arise from carrying out such research without having obtained explicit parental consent to do so when the samples were taken.