A simple cheek test could calculate how long a person has left to live.
Scientists have discovered a "cheeky" method of estimating a patient's risk of death by using cells found inside the mouth.
US experts have developed the CheekAge technique that enables doctors to extract DNA methylation from inside the cheeks before accurately predicting the risk of mortality, irrespective of which tissue the epigenetic data is taken from.
Previous methods developed by boffins had centred on DNA methylation in blood cells that made the collection of samples both complicated and stressful for the patient.
Dr. Maxim Shokhirev, head of computational biology and data science at the Tally Health company in New York, said: "The fact that our epigenetic clock trained on cheek cells predicts mortality when measuring the methylome in blood cells suggests there are common mortality signals across tissues.
"This implies that a simple, non-invasive cheek swab can be a valuable alternative for studying and tracking the biology of ageing."