Age determination through DNA methylation patterns in fingernails and toenails

Area of Science:

• Forensic Science
• Epigenetics
• Biochemistry

Background:

• DNA methylation is a key epigenetic mechanism influencing gene expression.
• Epigenetic clocks, particularly DNA methylation-based, are established for biological age prediction.
• Nails, resistant to decay and easy to sample, present an unexplored tissue for age prediction.

Purpose of the Study:

• To investigate the potential of nail DNA methylation for chronological age prediction.
• To develop and evaluate age prediction models using nail samples.
• To assess the feasibility of nail-based age prediction in post-mortem cases.

Main Methods:

• Collected fingernail and toenail clippings from 108 individuals (0-96 years).
• Analyzed methylation status of 15 CpGs in 4 age-related genes (ASPA, EDARADD, PDE4C, ELOVL2) using pyrosequencing.
• Developed limb-specific and combined models for age prediction.

Main Results:

• Significant methylation differences observed across limbs.
• Age prediction models achieved a mean absolute deviation of 5.48–9.36 years.
• Successfully applied the assay to post-mortem nail samples.

Conclusions:

• Chronological age can be reliably assessed using DNA methylation patterns in human nails.
• Nail-based age prediction offers advantages for forensic applications, especially in degraded samples.
• This study establishes nails as a viable source for epigenetic age estimation.